• TABLE OF CONTENTS
HIDE
 Title Page
 Acknowledgement
 Table of Contents
 List of Tables
 List of Figures
 Abstract
 Chapter 1: Introduction
 Figure 1.1
 Figure 1.2: Diagram of Fraternidad...
 Chapter 2: Macroinvertebrates used...
 Figure 2.1: Sampling protocol for...
 Table 2.1: List of macroinvertebrates...
 Table 2.2: Comparison of salinity...
 Figure 2.2: Change in invertebrate...
 Figure 2.3: Changes in invertebrate...
 Figure 2.4: Rainfall at Cabo Rojo...
 Figure 2.5: Height of high and...
 Figure 2.6: Water level and sailinity...
 Figure 2.7: Water level and salinity...
 Figure 2.8: Salinity measurements...
 Figure 2.9: Monthly rainfall at...
 Chapter 3: Habitat use patterns...
 Figure 3.1: Weekly survey...
 Figure 3.2: Protocol for high-use/low-usre...
 Figure 3.3: Determination of relative...
 Figure 3.4: Members of calidrids...
 Figure 3.5: Distribution of foraging...
 Figure 3.1: Maximum counts and...
 Figure 3.6: Important invertebrate...
 Figure 3.7: Results of diet analysis...
 Figure 3.8: Results of diet analysis...
 Figure 3.2: Analyses of variance...
 Figure 3.9: Mean numbers of individuals...
 Table 3.4: Mean percent cover values...
 Table 3.5: Simultaneous Bonferroni...
 Figure 3.10: Observed and expected...
 Table 3.6: Mean percent cover values...
 Figure 3.11: Observed and expected...
 Chapter 4: Conclusion and management...
 Appendix: Shorebird species encountered...
 Reference






Title: Habitat use by migratory shorebirds at the Cabo Rojo Salt Flats, Puerto Rico
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00067402/00001
 Material Information
Title: Habitat use by migratory shorebirds at the Cabo Rojo Salt Flats, Puerto Rico
Physical Description: x, 93 leaves : ill. ; 29 cm.
Language: English
Creator: Grear, Jason S., 1963-
Publication Date: 1992
 Subjects
Subject: Shore birds -- Habitat -- Puerto Rico -- Cabo Rojo Salt Flats   ( lcsh )
Shore birds -- Feeding and feeds -- Puerto Rico -- Cabo Rojo Salt Flats   ( lcsh )
Shore birds -- Cabo Rojo Salt Flats -- Ecology -- Puerto Rico   ( lcsh )
Cabo Rojo Salt Flats (P.R.)   ( lcsh )
Forest Resources and Conservation thesis M.S
Dissertations, Academic -- Forest Resources and Conservation -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis (M.S.)--University of Florida, 1992.
Bibliography: Includes bibliographical references (leaves 82-91).
Statement of Responsibility: by Jason S. Grear.
General Note: Typescript.
General Note: Vita.
General Note: Also published as Technical report no.46.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00067402
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 001800201
oclc - 27569264
notis - AJM3950

Table of Contents
    Title Page
        Title Page
    Acknowledgement
        ii
        iii
    Table of Contents
        iv
    List of Tables
        v
    List of Figures
        vi
        vii
    Abstract
        viii
        ix
    Chapter 1: Introduction
        Page 1
        Page 2
    Figure 1.1
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Figure 1.2: Diagram of Fraternidad system showing habitat units, measurement stations, and location of invertebrate sampling plots
        Page 9
        Page 10
        Page 11
        Page 12
    Chapter 2: Macroinvertebrates used by migratory calidrid shorebirds and physical patterns associated with their abundance and distribution
        Page 13
        Page 14
        Page 15
    Figure 2.1: Sampling protocol for permanent plots
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
    Table 2.1: List of macroinvertebrates encountered by site
        Page 21
    Table 2.2: Comparison of salinity among habitat units using invertebrate sampling data
        Page 22
    Figure 2.2: Change in invertebrate abundance based on permanent sampling plot in the east lagoon
        Page 23
    Figure 2.3: Changes in invertebrate abundance based on permanent sampling plot in the mud flat
        Page 24
        Page 25
    Figure 2.4: Rainfall at Cabo Rojo National Wildlife Refuge (1990)
        Page 26
    Figure 2.5: Height of high and low tides at Isla Magueyes in 1990
        Page 27
    Figure 2.6: Water level and sailinity at east (a) and west (b) culverts in 1990
        Page 28
        Page 29
    Figure 2.7: Water level and salinity at east culvert in 1991
        Page 30
    Figure 2.8: Salinity measurements from five station in Fraternidad system during 1986
        Page 31
    Figure 2.9: Monthly rainfall at the Cabo Rojo National Wildlife Refuge from 1981 to 1991
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
    Chapter 3: Habitat use patterns by migratory Calidrid shorebirds
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
    Figure 3.1: Weekly survey route
        Page 43
        Page 44
        Page 45
        Page 46
    Figure 3.2: Protocol for high-use/low-usre invertebrate sampling
        Page 47
        Page 48
        Page 49
    Figure 3.3: Determination of relative contour for individual grid points
        Page 50
        Page 51
        Page 52
    Figure 3.4: Members of calidrids and distribution of foraging and roosting birds among the two major lagoon systems during 1990 and 1991-92 weekly surveys
        Page 53
        Page 54
    Figure 3.5: Distribution of foraging calidrids among habitat units during 1990 daily survey
        Page 55
    Figure 3.1: Maximum counts and regression analyses (count vs. date) on daily surveys of the Fraternidad system
        Page 56
    Figure 3.6: Important invertebrate taxa
        Page 57
    Figure 3.7: Results of diet analysis of calidrids in 1990 and 1991 expressed as percent occurrences among samples
        Page 58
    Figure 3.8: Results of diet analysis of calidrids in 1990 and 1991 expressed as mean number per sample
        Page 59
        Page 60
        Page 61
    Figure 3.2: Analyses of variance on high-use vs. low-use data
        Page 62
    Figure 3.9: Mean numbers of individuals in high-use and low-use patches in 1990 and 1991
        Page 63
    Table 3.4: Mean percent cover values of substrate types for each habitat cluster
        Page 64
    Table 3.5: Simultaneous Bonferroni confidence intervals for bird sightings among ten habitat cluster types
        Page 65
    Figure 3.10: Observed and expected proportions of bird sightings among ten habitat cluster types
        Page 66
    Table 3.6: Mean percent cover values of usbstrate types for each habitat cluster
        Page 67
    Figure 3.11: Observed and expected proportions of bird sightings among five habitat cluster types
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
        Page 74
        Page 75
    Chapter 4: Conclusion and management recommendations
        Page 76
        Page 77
        Page 78
        Page 79
    Appendix: Shorebird species encountered at the Cabo Rojo Salt Flats
        Page 80
        Page 81
    Reference
        Page 82
        Page 83
        Page 84
        Page 85
        Page 86
        Page 87
        Page 88
        Page 89
        Page 90
        Page 91
Full Text

















TECHNICAL REPORT NO. 46

Habitat Use by
Migratroy Shorebirds
at the Cabo Rojo Salt Flats,
Puerto Rico




By
Jason S. Grear
Florida Cooperative Fish and Wildlife Research Unit
U.S. Fish and Wildlife Service
University of Florida
Gainesville, FL 32611


Research Work Order No. 78
August 1992















ACKNOWLEDGEMENTS


This research was funded by Cooperative Agreement No.

14-16-0009-1544, Research Work Order No. 78 between the U.S.

Fish and Wildlife Service and the University of Florida

through the Florida Cooperative Fish and Wildlife Research

Unit.

I would like to thank Dr. Jaime Collazo for providing me

this opportunity and for his support and advice throughout

the project. Hilda Diaz-Soltero and Jim Oland of the

Caribbean Field Office in Boqueron, Puerto Rico enthusias-

tically sponsored the project from start to finish. Dr.

Franklin Percival of the Florida Cooperative Fish and

Wildlife Research Unit provided invaluable advice and

support. Drs. Collazo and Percival also served on my

advisory committee with Drs. Susan Jacobson and Douglas

Levey. The committee provided helpful technical and

editorial comments on my research and thesis manuscript.

Brian Harrington of the Manomet Bird Observatory made

the initial visit to the study site possible before this

project began. His support and advice persisted through the

entire project and were based on first-hand experience at the

study site and his exceptional knowledge of shorebird

ecology.


ii









Willard Hill (Sal de Borinquen, Inc.) kindly allowed

access to the study area and provided valuable data on

salinity patterns in the Fraternidad lagoon. Edward Ellis

assisted me in the field during both field seasons and Jose

Col6n conducted weekly shorebird surveys during autumn and

winter of 1991-92. Barbara Fesler and the rest of the staff

of the Florida Cooperative Fish and Wildlife Research Unit

provided superb logistical support and the feeling that

someone on the UF campus was looking out for me. Puerto

Rico's Departamento de Recursos Naturales assisted in several

ways, the most important of which was their issuance of

animal use permits. Dr. Willis Wirth provided assistance in

the identification of insect specimens collected at the study

site.

Joan Goldenthal Grear and my family in Massachusetts

were the biggest help of all.


iii


















TABLE OF CONTENTS


ACKNOWLEDGEMENTS .......................................... ii

LIST OF TABLES .............................................. V

LIST OF FIGURES ............................................ vi

ABSTRACT ................................................ xiii

INTRODUCTION ............................................... 1


Rationale and Objectives..............
Study Area ............................
General Description ................
Habitat Units ......................


. ..6
...6


.................... 8


MACROINVERTEBRATES USED BY MIGRATORY CALIDRID SHOREBIRDS
AND PHYSICAL PATTERNS ASSOCIATED WITHTHEIR ABUNDANCE
AND DISTRIBUTION............................... ........ 13

Introduction...................................... ....... 13
Methods................ ................................. 15
Results ..................... .. ................. ....... 20
Discussion...... ....................... ..... ...... 33

HABITAT USE PATTERNS BY MIGRATORY CALIDRID SHOREBIRDS ......37


Introduction..............................
Methods . . ...........................
Numbers and Distribution of Birds ......
Shorebird Diet and Foraging Substrata ..
Invertebrate Sampling ..................
Shorebird and Habitat Mapping ..........
Results ...................................
Numbers and Distribution of Birds ......
Shorebird Diet and Foraging Substrata ..
Invertebrate Sampling ..................
Shorebird and Habitat Mapping ..........
Discussion...................... ...


........ 37
........ 42
........ 42
........ 44
...... 46
.... ... 48
........52
.... 52
....... .56
........60
........64
........69


CONCLUSION AND MANAGEMENT RECOMMENDATIONS .................. 76

APPENDIX SHOREBIRD SPECIES ENCOUNTERED AT THE CABO ROJO
SALT FLATS ............................................... 80

REFERENCES .............................................. .. 82


iv


...........
...........
..........O














LIST OF TABLES


Table 2.1. List of macroinvertebrates encountered by site
(within Fraternidad system).............................. 21

Table 2.2. Comparison of salinity among habitat units using
invertebrate sampling data............................... 22

Table 2.3. Comparison of water temperature among habitat
units using invertebrate sampling data................... 22

Table 2.4. Spearman correlations for invertebrate density
vs. salinity ............................................. 22

Table 3.1. Maximum counts and regression analyses (count vs.
date) on daily surveys of the Fraternidad system......... 56

Table 3.2. Analyses of variance on high-use vs. low-use
data ..................................................... 62

Table 3.3. Analyses of variance and Tukey's honestly
significant difference test on invertebrate data from
different substrata in the middle lagoon................. 63

Table 3.4. Mean percent cover values of substrate types for
each habitat cluster (10-cluster analysis)............... 64

Table 3.5. Simultaneous Bonferroni confidence intervals for
bird sightings among ten habitat cluster types........... 65

Table 3.6. Mean percent cover values of substrate types for
each habitat cluster (5-cluster analysis) ................ 67

Table 3.7. Simultaneous Bonferroni confidence intervals for
bird sightings among five habitat cluster types.......... 67


v














LIST OF FIGURES

Figure 1.1. The Cabo Rojo Salt Flats, at the southwest tip
of Puerto Rico....................................... ... 3

Figure 1.2. Diagram of Fraternidad system showing habitat
units, measurement stations, and locations of invertebrate
sampling plots............................................. 9

Figure 2.1. Sampling protocol for permanent plots ......... 16

Figure 2.2. Changes in invertebrate abundance based on
permanent sampling plot in the east lagoon............... 23

Figure 2.3. Changes in invertebrate abundance based on
permanent sampling plot in the mud flat.................. 24

Figure 2.4. Rainfall at Cabo Rojo National Wildlife Refuge
in 1990.............. .. .. ................. ............. 26

Figure 2.5. Heights of high and low tides at Isla Magueyes
in 1990............................................. . 27

Figure 2.6. Water level and salinity at east (a) and west
(b) culverts in 1990........................ ............ 28

Figure 2.7. Water level and salinity at east culvert in
1991..................................................... 30

Figure 2.8. Salinity measurements from five stations in
Fraternidad system during 1986........................... 31

Figure 2.9. Monthly rainfall at the Cabo Rojo National
Wildlife Refuge from 1981 to 1991........................ 32

Figure 3.1. Weekly survey route .......................... 43

Figure 3.2. Protocol for high-use/low-use invertebrate
sampling................................................. 47

Figure 3.3. Determination of relative contour for individual
grid points ...................................... ........ 50

Figure 3.4. Numbers of calidrids and distribution of
foraging and roosting birds among the two major lagoon
systems during 1990 and 1991-92 weekly surveys........... 53


vi








Figure 3.5. Distribution of foraging calidrids among habitat
units during 1990 daily surveys.......................... 55

Figure 3.6. Important invertebrate taxa (Trichocorixa,
Dasyhelea larvae and pupae, Artemia). Bill of a
Semipalmated Sandpiper................................... 57

Figure 3.7. Results of diet analysis of calidrids in 1990
and 1991 expressed as percent occurrence among samples...58

Figure 3.8. Results of diet analysis of calidrids in 1990
and 1991 expressed as mean number per sample............. 59

Figure 3.9. Mean numbers of individuals in high-use and low-
use patches in 1990 and 1991............................ 63

Figure 3.10. Observed and expected proportions of bird
sightings among ten habitat cluster types................ 66

Figure 3.11. Observed and expected proportions of bird
sightings among five habitat cluster types............... 68


vii















ABSTRACT


HABITAT USE
BY MIGRATORY SHOREBIRDS
AT THE CABO ROJO SALT FLATS,
PUERTO RICO

By

JASON S. GREAR

August, 1992


Chairman: Jaime A. Collazo, PhD
Major Department: Forest Resources and Conservation
(Wildlife and Range Sciences)

The Cabo Rojo Salt Flats, at the southwestern tip of

Puerto Rico, provide important autumn stopover and wintering

habitat for migratory shorebirds. I studied the abundance

and distribution of shorebirds and their food resources at

this site during autumn of 1990 and 1991.

Small calidrids (primarily Calidris pusilla and C.

mauri) were the most abundant shorebirds at the salt flats.

The maximum weekly counts of small calidrids in 1990 (2,690)

and 1991 (3,532) occurred in mid October. Calidrids foraged

primarily in the Fraternidad lagoon system; roosting took

place most often at the neighboring Candelaria Lagoon.

The macroinvertebrate prey important to calidrids in the

Fraternidad system were Dasyhelea (Diptera), Trichocorixa

(Hemiptera), and Artemia (Anostraca). Changes in inver-

tebrate abundance coincided with fluctuations in salinity.


viii









These fluctuations were induced by the combined influences of

tides, evaporation, and rainfall. On a more seasonal basis,

desiccation of algal mats influences the timing of inver-

tebrate productivity.

Shifts in the diets and among-habitat distribution of

calidrids were associated with changes in food abundance; in

other cases when food abundance did not change, shifts were

associated with increased water levels such that prey became

inaccessible to foraging calidrids. Within a preferred

lagoon, differences in prey abundance among patches of

differing levels of use by calidrids (high vs. low) were not

strong, except in areas where only Artemia were present.

Using mapping data, I found significant correlations between

algal substrate type and the abundance of calidrids and their

prey. This suggests that calidrids may select foraging sites

based on algal physiognomy. The lack of clear differences

between high-use and low-use patches may have been due to

sampling across substrate types.

Every site within the salt flats serves as important

habitat to at least one shorebird species. Conditions in

these habitats are influenced by varying levels of human

manipulation. Management of the salt flats must therefore be

based on a clear understanding of the hydrologic regimes

maintaining this broad range of habitat conditions.


ix















CHAPTER 1
INTRODUCTION


Rationale and Objectives


Migratory shorebirds (Charadrii and Scolopaci) may spend

over 65% of the year at stopover areas and wintering grounds

(Senner and Howe 1984). Many individuals use the same areas

year after year. The quality and availability of stopover

areas and wintering grounds affect over-winter survival and

are therefore critical to the stability of shorebird

populations (Myers et al. 1987). The conservation of many

shorebird species depends on our ability to locate, describe,

and protect critical links in migration.

As an important component of wetland wildlife,

shorebirds represent an international link in the global

problem of wetland habitat destruction. This link has been

recognized by a wide array of government and nongovernment

organizations participating in the PanAmerican Shorebird

Program and International Shorebird Survey (Myers 1983,

Harrington et al. 1989), such as the U.S. Fish and Wildlife

Service, the Canadian Wildlife Service, the Western

Hemisphere Shorebird Reserve Network, and the World Wildlife

Fund. The Wader Study Group and the Asian Wetlands Bureau

have identified many sites important to shorebirds in the

western hemisphere. The migratory routes of shorebirds have


1






2

been summarized in Pienkowski and Evans (1984), Morrison

(1984), and Myers et al. (1987).

In Puerto Rico, shorebirds are one of the least-studied

groups of birds. Available information consists of

checklists, notes, and short-term surveys (e.g., Biaggi 1983,

Danforth 1929, Leopold 1963, McCandless 1961 and 1962, Moreno

and Perez 1980, Raffaele 1989, Wetmore 1916). Pressing

demands to develop wetlands and shoreline habitats for

multiple uses represent the major threat to the continued

existence of both migratory and resident shorebirds in Puerto

Rico (Moreno and P6rez 1980, Raffaele and Duffield 1979). As

a first step toward habitat protection, Raffaele and Duffield

(1979) identified the Cabo Rojo Salt Flats (Figure 1.1) as

one of the prime habitats for migratory and resident

shorebirds. Nearly every publication and unpublished list of

Puerto Rico's most valuable wetlands and wildlife habitats

includes the Cabo Rojo Salt Flats (e.g., Collazo et al. 1987,

Del Llano et al. 1986, Moreno and Perez 1980, Ortiz-Rosas and

Quevedo-Bonilla 1987, Raffaele and Duffield 1979).

In an effort to contribute to the knowledge of migration

patterns through the eastern Caribbean, the U.S. Fish and

Wildlife Service and the Commonwealth Department of Natural

Resources have supported research and monitoring programs at

the Cabo Rojo Salt Flats since 1985. Findings indicate that

this hypersaline lagoon system is the single most important

converging point for migrating shorebirds on the island

during autumn migration and winter. During spring migration,







3


I.. I.. :. I. I.. I.. I.. I.., .... ". 1. I. .I.. I... I... I.. I.. *.. %. *.. .. I.... 1.. -1. .. *. .. .. %. .,,

. .. .. .. . . .o l
.: ." .- .: .. .:.
. . .. . ." .. .- . .
... ... .. ... ...
. . ........ .
. . .... . . . . .. .
'..:.:. -.'. ..- .. ;.. .."- ..'."..' ...;- .' '."
.r a ..'. -. ...- ...: -.,. .-.... .' .

.. ....".. .Fraternidad




a .. .. .h u




:':Bahia Sucia


k.


500 m


SFl FAmr


Figure 1.1. The Cabo Rojo Salt Flats, at the southwest tip
of Puerto Rico.


~a~1






4


only small numbers of migrants stop in Puerto Rico. Thirty-

two species of shorebirds have been seen at the salt flats

(Appendix). Small calidrids (primarily Calidris pusilla and

C. mauri) comprise 60-70% of the shorebirds present on the

flats during autumn migration. Harrington (1982) and

Harrington and Morrison (1979) discussed the migratory

patterns of C. pusilla in the western hemisphere (also see

review by Morrison 1984). Information on the migration of C.

mauri is less complete but has been discussed in Senner and

Martinez (1982) and Senner et al. (1981).

Migratory species start to arrive at the Cabo Rojo Salt

Flats in late July. Many individuals may remain through the

winter, but others depart before December. Four shorebird

species breed at the flats: Black-necked Stilt (Himantopus

himantopus), Killdeer (Charadrius vociferus), Wilson's Plover

(C. wilsonia), and Snowy Plover (C. alexandrinus). The

locally threatened Snowy Plovers are found nowhere else on

Puerto Rico (Biaggi 1983, Collazo et al. 1987, Lee 1989,

Raffaele 1989). Numerous aquatic birds and seabirds have

been seen at the area. Included among these are the White-

cheeked Pintail (Anas bahamensis, a candidate for the federal

list of endangered species), the federally endangered Brown

Pelican (Pelicanus occidentalis), and the Least Tern (Sterna

antillarum). The flats are also within the designated

critical habitat of the federally endangered Yellow-

shouldered Blackbird (Agelaius xanthomus).






5


The apparent similarity of salt flat systems around the

world widens the scope of my study. The worldwide

distribution of hypersaline coastal ecosystems is described

in Chapman (1977), where it is also suggested that

hypersaline conditions may be prevalent on river mouth mud

flats along the Patagonian coast of South America. This may

be critical to the study of shorebirds, since many species

winter in southern South America. Lankford (1977) devised a

classification system for Mexico's 123 coastal lagoons, many

of which become hypersaline at certain times of the year.

The use of coastal ecosystems throughout the tropics by

migratory shorebird populations should be studied in detail.

There is strong pressure for development of coastal lagoons

in Puerto Rico as well as other areas in the neotropics. As

of 1988, for example, 120,000 ha of shrimp ponds had been

constructed within Ecuador's 3,000 km coastline (Matuszeski

et al. 1988). Many of these ponds have replaced mangrove

forests and lagoons.

While efforts to ensure the protection of the Cabo Rojo

Salt Flats have been made by Commonwealth and Federal

agencies and non-government organizations, the preparation of

a management plan and the ability to assess potential impacts

of habitat alterations has been hampered by the lack of basic

knowledge about the use of the salt flats by shorebirds. The

continued use and value of the Cabo Rojo Salt Flats as a

migratory stopover and wintering area is related to the

availability and abundance of food resources (Goss-Custard






6


1979, Hicklin and Smith 1984, Myers et al. 1980, 1987).

Thus, my study was designed to obtain baseline data on the

biological resources present at the Cabo Rojo Salt Flats, the

underlying factors influencing these resources, and how they

are used by migratory shorebirds. These data were collected

in 1990 and 1991 to address the following project objectives:


Objective 1. To describe macroinvertebrate assemblages
exploited by migratory Calidris sandpipers and the
physical patterns associated with their distribution
(Chapter 2).


Objective 2. To relate the distribution of migratory
Calidris sandpipers to habitat resource patterns at the
within- and among-habitat levels (Chapter 3).


I expect that these data will strengthen conservation

and management efforts at this unique stopover and wintering

area in the eastern Caribbean. Furthermore, as additional

data from other sites accumulate, questions such as how and

why the use of tropical wetlands by migratory shorebirds

differs from that of temperate wetlands will be more easily

answered.


Study Area


General Description


The Cabo Rojo Salt Flats lie at the southwestern tip of

Puerto Rico (Figure 1.1). The salt flats system is roughly






7


445 ha (1,100 acres) in area and consists primarily of two

large shallow lagoon systems (Candelaria and Fraternidad)

separated from the Caribbean Sea by narrow strips of mangrove

and scrub vegetation. The salt flats are bordered on the

east and southwest ends by the mangroves and beaches of

Bosque Estatal de Boquer6n (Boquer6n State Forest) and on the

northeast by the upland dry forest of the Cabo Rojo National

Wildlife Refuge. These areas represent over 810 ha (2,000

acres) of prime habitat for the protection of Puerto Rico's

resident and migratory wildlife.

Dikes and barriers are maintained in both lagoon systems

by a low-intensity solar salt production company (Sal de

Borinquen, Inc.). Sea water is allowed to flow into the

lagoons via several narrow sluices. After dissolved salts

begin to accumulate, water is pumped into diked evaporation

basins (crystallizers) from the lagoon and salt precipitates

are harvested for commercial sale. In the Fraternidad lagoon

system (Figure 1.1), sea water enters near the east end and

is pumped into crystallizers from the west end of the lagoon,

where salinity levels approach saturation.

For several kilometers east of the Cabo Rojo Salt Flats,

dense mangrove stands are interspersed with small open pools.

It is likely that many of these pools are hypersaline. While

it is clear that hypersaline lagoons often form naturally as

a dynamic phase in mangrove forests of arid coastal

environments (Cintr6n et al. 1978), the dikes and barriers at






8


the Cabo Rojo Salt Flats appear to have arrested vegetation

succession in several portions of the system.


Habitat Units


Shorebirds used a wide range of habitat types at the

Cabo Rojo Salt Flats. Discrete habitat units within the

Fraternidad system were identified (Figure 1.2). I refer to

these habitat units throughout Chapters 2 and 3. Borders

between habitat units are typically defined by physical

features such as dikes and barriers maintained by the salt

production company. A description of each unit is provided

below with a summary of important characteristics at the end

of the section.



Mangrove Pool. The mangrove pool is an open water area

surrounded by mangroves (Avicennia and Rhizophora). It is

bordered to the south by a narrow barrier beach. Sea water

interchange with Bahia Sucia occurs through a narrow channel

in the mangroves in the southeast corner of the area. At the

east and west ends, dead sun-bleached mangrove snags are

interspersed with shallow muddy areas. These muddy areas

become exposed during periods of low water. Most of the

mangrove pool area is greater than 5 cm deep.



East Lagoon. This is a large area connected at its

southeastern corner to the mangrove pool by a narrow channel

through mangroves. During my study, most of the area was






9


Permanent Plot


Permanent Plot


Trench


Plastic


East
Culvert


West Culvert


: Mangrove Pool


East Lagoon N


Middle Lagoon


- Mud Flat Area


^: West Lagoon


1km


Figure 1.2. Diagram of Fraternidad system showing habitat
units, measurement stations, and locations of invertebrate
sampling plots.


I






10


open water greater than 5 cm deep. The shorelines are of low

aspect and in areas where blue-green algal mats are well-

developed (primarily the southwest, west, and northwest

edges), periods of low water result in the exposure of

mudflats. There is a small stand of Acacia/Prosopis trees

beyond the southwest corner of the area and small mangrove

saplings are scattered around the borders. The Cabo Rojo

National Wildlife Refuge and a cattle grazing area lie 10-20

meters north of the water's edge.



Middle Lagoon. This area is separated from the east

lagoon by a paved dike. The dike provides access and a

utility right-of-way to a small fishing camp on the barrier

beach just south of this lagoon. Water flows between the

east and middle lagoons via two small culverts that pass

through the dike. The northernmost culvert is partially

blocked with sediments. A small stream enters the northeast

corner of the lagoon from the Cabo Rojo National Wildlife

Refuge, which borders the entire northern edge of this area.

Dense stands of Acacia/Prosopis dominate this portion of

wildlife refuge. A small channel connects the southwest

corner of the middle lagoon to Bahia Sucia. Water movement

through this channel is partially restricted by mangroves.

The middle lagoon was almost completely dry in late August of

1990, except for an area roughly 50 m in diameter immediately

west of the main culvert. Following increased rainfall and

tidal input in mid October 1990, the lagoon became inundated






11


with water and lush algal mats appeared throughout much of

the area.



Mud Flat. The mud flat area is bordered to the east by

a dike that separates it from the middle lagoon and by a

deteriorated wooden structure built by the salt production

company. The intended function of this structure is to

filter detritus as sea water enters the system through the

west culvert (Figure 1.2). The mud flat is part of a larger

lagoon that is separated from the adjacent west lagoon by a

decaying plastic barrier. Since the northern end of the

barrier is only partially intact, the northwest half of this

lagoon is functionally part of the west lagoon. The

southeast half is covered with a lush algal mat and is quite

distinct from the northwest half and the west lagoon. This

algal mat is referred to as the mud flat area (Figure 1.2).

In late August of 1990, the mud flat area had only a shallow

layer of water (less than 4 cm). Throughout late October and

November of the 1990 field season, there was over 6 cm of

water covering the entire mud flat area. Water levels were

low during the 1991 season as a result of a tidal barrier

placed at the west culvert and most of the mud flat had less

than 1 cm of water overlying it.



West Lagoon. This is the largest lagoon and is bordered

at its east end by the mud flat area and at the west end by

the salt crystallizing basins. Most of the area is greater







12


than 6 cm deep and the southern edge, which is bordered by a

narrow barrier beach with stands of Acacia/Prosopis has a

rather steep aspect. The northern edge, however, is shallow

with wide sandy shores and occasional stands of Salicornia,

Sesuvium, and Acacia/Prosopis. Throughout most of the

lagoon, the bottom is covered with a hard sandy crust that is

often pink in color. Water levels in this lagoon are

partially manipulated by the salt production company.



Summary of Habitat Units. Habitat studies focused on

the east and middle lagoons, the mud flat, and the west

lagoon. Of these four units, tidal flow was least obstructed

at the mud flat during 1990. Ephemeral lagoons at the east

end (east and middle lagoons) receive both tidal and runoff

inputs. Conditions in the deeper and more permanently

flooded west lagoon are maintained by the salt production

company. The west lagoon is also the only unit where

extensive algal mats do not occur.















CHAPTER 2
MACROINVERTEBRATES USED BY MIGRATORY CALIDRID SHOREBIRDS
AND PHYSICAL PATTERNS ASSOCIATED WITH
THEIR ABUNDANCE AND DISTRIBUTION


Introduction




The value of the Cabo Rojo Salt Flats as a migratory

stopover has been established by cumulative data collected

since 1985 and those contributed by this study (Chapter 3).

The continued use and value of this stopover is related to

the availability and abundance of food resources (Goss-

Custard 1979, Hicklin and Smith 1984, Myers et al. 1980,

1987). In this chapter, I describe the salt flat

macroinvertebrate community used by migratory calidrid

sandpipers (Calidris pusilla, C. mauri, C. minutilla, C.

fuscicollis, and C. bairdii).

Salt flat habitats are interspersed among mangrove

forests of southern Puerto Rico from Guayama to Cabo Rojo.

These hypersaline ecosystems attain landscape dominance at

Cabo Rojo, where mangroves are reduced to a thin fringe. The

salt flats are part of an important complex in southwest

Puerto Rico that includes coral reefs, seagrass beds,

mangroves and uplands. Some of the unique ecosystem

characteristics of hypersaline systems were examined and


13






14


reviewed by Armstrong (1982), Copeland and Nixon (1974),

Javor (1989), Nixon (1969), and Odum et al. (1971). Davis

(1978, 1979) discussed basic physiological aspects of

organisms inhabiting evaporation ponds of tropical and

subtropical solar salt systems.

Ecosystem and physiology studies show that, in

hypersaline systems, mobilization of nutrients from organic

compounds may be a limiting factor to which organisms must

adapt (Odum et al. 1971). This reduced mobilization of

nutrients is due to the truncation of the detritivore

community by hypersaline conditions. Several species of

blue-green algae (Cyanophyta) and green algae (Chlorophyta)

tolerate hypersaline conditions and frequent desiccation;

they are the most important primary producers in the salt

flat system. Large-scale commercial salt producers elsewhere

in the Caribbean have recognized the importance of the algal

communities for the absorption of the sun's energy that, in

turn, is necessary for evaporation (J. Davis, personal

communication). The algae are typically fed upon by brine

shrimp (Artemia) and several species of salt-tolerant

insects. These and many other ecosystem characteristics are

shared with every documented tropical salt flat system

globally (J. Davis, personal communication).

During shorebird migration at the Cabo Rojo Salt Flats

in autumn 1990 and 1991, I collected baseline data on

macroinvertebrate abundance and distribution, and the

underlying factors influencing these parameters. These data






15


are necessary to formulate appropriate habitat management

strategies for maintaining resource availability in the salt

flats. Thus, data and analyses in this chapter address the

following objective:


Objective 1. To describe macroinvertebrate assemblages
exploited by migratory Calidris sandpipers and the
physical patterns associated with their distribution.




Methods


I set up two permanent plots in 1990 to detect changes

in invertebrate numbers through the season in the east lagoon

and the mud flat area. I selected these units because they

were considered to represent distinctly different habitat

types. Within each unit, I located the permanent plots in

areas that were representative of the entire habitat unit in

terms of slope, depth and substrate character. Samples also

were collected in the west lagoon and middle lagoon as part

of other habitat use studies (Chapter 3).

Permanent plots were sampled every two weeks for a

period of 10 weeks. On a sampling day, I collected six sets

of samples at each plot (see Figure 2.1). Each set consisted

of one water column sample and one sediment sample. Each

plot was 50 m wide. I stratified the six sample sets so that

two sets were taken from each of three zones: shallow water

(1-2 cm); intermediate depth (3-7 cm); and deep water (8-12






16


0 5 9


91-


deep


intermediate


shallow


- 152


M 27


0
10m~i -


shore -
I- 50 m


(a)


(b)


Figure 2.1. Sampling protocol for permanent plots. One 10 x
10 m quadrat was randomly chosen from within each of three
zones (a). Within each 10 x 10 m quadrat, two 1 x 1 m
subplots were randomly selected for sampling (b).


5






17


cm). Depth zones ran parallel to the shore for a distance of

50 m. The purpose of this depth stratification was to

broaden the scope of sampling, rather than to allow between-

zone comparisons. I then randomly selected one 10 x 10 m

section from each of these strips for a particular sampling

day. After five sampling days (8 weeks), each 10 m section

of the 50 m strips had been sampled. This protocol prevented

repeated sampling of each 10 x 10 m quadrat since sampling

activity resulted in considerable alteration of substrata

(i.e., footprints) that often persisted for several weeks.

The samples taken from each zone also were randomly located

within their 10 m quadrats. Thus, for each permanent plot,

there are 5 sets of 6 water column samples and 5 sets of 6

mud samples.

I collected samples by first identifying the exact

location of a sample from a distance of =1.5 m. Then, in a

rapid motion, I placed a steel cylinder (diameter = 9.92 cm,

open at both ends) vertically on the site and inserted it

into the mud. This motion was done in one quick step in

order to minimize the escape of swimming invertebrates. I

quickly stirred the water and loose detritus inside the

cylinder and transferred them into a marked plastic container

using a water suction device (turkey baster). The cylinder

was then reinserted into the mud adjacent to the location of

the water column sample to a depth of 1.5 cm and a sediment

core sample was lifted with the aid of a mason's trowel.






18


These samples were placed in marked plastic bags where they

remained intact.

I processed all samples at the Cabo Rojo National

Wildlife Refuge. Water column samples were poured into white

dissecting pans and all visible invertebrates were counted

and classified into morphospecies. I processed sediment

samples using a "drying oven." The drying technique is

similar to the use of a Berlese funnel. The intact core

samples were placed on a plastic screen (1 mm mesh size) that

suspended each sample over a separate bowl of water. This

apparatus was enclosed within a cubical wooden box with an

exhaust port and fan on its underside and a 200 watt lamp

directly over the samples. The light and fan were then left

on for 24 hours. As the sediment samples dried out,

invertebrates burrowed downward through the underlying screen

and into the bowl of water. I removed these bowls and

counted and classified all visible invertebrates into

morphospecies. Other processing techniques were attempted

but were neither efficient nor repeatable. These included

visual inspection, sieving, an agar technique (Kline et al.

1981), elutriation (Magdych 1981), and suspension of

organisms in sucrose solution. Invertebrate specimens

collected during the sampling efforts were preserved and

identified to the lowest possible taxonomic level with the

assistance of Dr. Willis Wirth and the Division of Plant

Industries in Gainesville, Florida.






19


I monitored water level and salinity during the study.

Rainfall data were obtained from the Cabo Rojo National

Wildlife Refuge. I used tide prediction tables from

Galveston, Texas and correction tables for Isla Magueyes,

Puerto Rico (NOAA 1989) to determine tide heights at

different times during the field season. Time corrections

between Isla Magueyes and the Cabo Rojo Salt Flats are

unknown. Tide data can therefore be compared only

qualitatively to water levels within the lagoons at the study

site. I measured water level and salinity daily at two sites

in the study area (see Figure 1.2). One site, referred to as

"east culvert," is located at a culvert that runs through a

dike between the east and middle lagoons. The other site,

referred to as the "west culvert" is located at a cinder

block culvert running between the mud flat and Bahia Sucia

(when not blocked). Salinity and water temperature were also

measured at the corner of each 10 m quadrat at the time of

sampling in the permanent plots and during all other

invertebrate sampling activity (Chapter 3). Salinity

measurements were taken with a temperature compensated

refractometer (Reichert-Jung model #10419). I also obtained

salinity data collected throughout 1986 at five stations in

the Fraternidad Lagoon system from Willard Hill (Sal de

Borinquen, Inc.).

I used Spearman correlation coefficients to examine

changes through time in the invertebrate sampling data from

permanent plots and relationships between salinity and






20


invertebrate density. I used analyses of variance to compare

salinity and water temperature among different habitat units.




Results

I described the habitat units of the Fraternidad system

in Chapter 1. Taxa encountered during all invertebrate

sampling are listed by habitat unit in Table 2.1. The most

prominent taxa were Trichocorixa (Hemiptera: Corixidae),

Dasyhelea (Diptera: Ceratopogonidae), Ephydra gracilis

(Diptera: Ephydridae), and Artemia (Anostraca).

Using data from invertebrate sampling efforts only, I

found a gradient in salinity among habitat units (Table 2.2).

Average water temperature was significantly higher (by <2

degrees Celsius) in the west lagoon than in the other three

areas (Table 2.3). Trichocorixa and Artemia occur in the

narrowest ranges within the salinity gradient (Table 2.4):

Trichocorixa occurs in the low salinity areas at the east

end; Artemia occurs in the hypersaline west end.

Mean numbers of invertebrates per sample from the

permanent plots in the east lagoon and the mud flat area

during the eight-week sampling period (1990) are shown in

Figures 2.2 and 2.3, respectively. I found a significant

positive correlation between numbers per sample and date

(N=30, 6 samples for each date) in the east lagoon for

Trichocorixa (Rho = 0.69, p < 0.001) and a negative

correlation for Stratiomyidae larvae (Rho = -0.38, p =






21


Table 2.1. List of macroinvertebrates encountered by site
(within Fraternidad system).


Taxon
Anostraca
Artemia
Decapoda
Uca
Chilopoda (dead adults)
Odonata (dead nymph)
Hemiptera
Saldidae (adults)
Hebridae (adults)
Corixidae
Trichocorixa
Mesoveleidae (adults)
Coleoptera (larvae)
Diptera
Cecidomyiidae (adults)
Ceratopogonidae
Dasyhelea

Culicoides (adults)

Chironomidae (larvae)
Stratiomyidae (larvae)
Tephritidae (adults)

Ephydridae
Ephydra gracilis (adults)

E. gracilis (larvae)
Glenanthe (adults)


Site(s)


West Lake

All sites
Middle Lagoon
Middle Lagoon

Mud Flat
Mud Flat

East and Middle Lagoons
West Culvert
Middle Lagoon

East and Middle Lagoons

East and Middle Lagoons, Mud
Flat
Mangroves, East and Middle
Lagoons
Middle Lagoon
Middle Lagoon and Mud Flat
East and Middle Lagoons, Mud
Flat

East and Middle Lagoons, Mud
Flat, West Lake
West Lake
East and Middle Lagoons






22


Table 2.2. Comparison of salinity among habitat units using
invertebrate sampling data. Fisher's protected least
significant difference test (PLSD, a=0.05) was used for
multiple comparisons. p = 0.000 for overall analysis of
variance (d.f. = 149, F = 155.26).
Unit n Mean Std. Dev. PLSD
East Lagoon 15 33 17 a
Middle Lagoon 84 41 16 a
Mud Flat 30 118 58 b
West Lagoon 24 151 49 c


Table 2.3. Comparison of water temperature among habitat
units using invertebrate sampling data. Fisher's protected
least significant difference test (PLSD, a=0.05) was used for
multiple comparisons. p = 0.001 for overall analysis of
variance (d.f. = 90, F = 5.8).
Unit n Mean Std. Dev. PLSD
East Lagoon 12 26.6 1.9 a
Middle Lagoon 40 27.4 1.3 a
Mud Flat 18 27.4 1.3 a
West Lagoon 24 28.4 0.9 b


Table 2.4. Spearman correlations for invertebrate density
vs. salinity. (N = 306; Diameter of each sample = 9.92 cm).
Rho Z
(corrected) (corrected) p
Artemia 0.62 10.76 0.000
Trichocorixa -0.33 5.67 0.000
Dasyhelea
larvae -0.16 2.78 0.005
pupae 0.00 0.00 0.998
Stratiomyidae
larvae -0.26 4.59 0.000







23


Dasyhelea Larvae
*


p
I I


Corixidae
*.
*.

4.^


I I I I


5-
4-
3-
2-
1-


Stratiomyidae Larvae




4.


0 !7
17
SEP


1 16O
OCT OCT


29
OCT


12
NOV


Figure 2.2. Changes in invertebrate abundance based on
permanent sampling plot in the east lagoon. Regression
lines shown only for those with significant Spearman
correlations (p < 0.05). N = 6 for each sample date.


3-


1 -
1


0


Q-
a_


CL
co

U)
-J
<:




z
LLU-
0
d
z


40-

30-

20-

10

0


A I


r w


I


- I






24


3

2



0-


40
Artemia
30 *
20
10-

0 ve I Ya j ---


10
8

4
4-
2-
0-


17 1
SEP OCT


16 29 12
OCT OCT NOV


Figure 2.3. Changes in invertebrate abundance based on
permanent sampling plot in the mud flat. Regression line
shown only for those wth significant Spearman
correlations (p < 0.05). N = 6 for each sample date.


Dasyhelea Larvae


LU
-J
CO

Cc






z
LL
0
0
z
-I


Stratiomyidae Larvae
4






25


0.040). Trichocorixa density in the east lagoon was

significantly and positively correlated with water level at

the east culvert (Rho = 0.378, p = 0.042). The increase in

Trichocorixa was noticeable even to the casual observer and

also appeared to occur in the middle lagoon, which is

connected to the east lagoon by culverts. In the permanent

plot in the mud flat, there was a significant positive

correlation between Artemia and sample date (Rho = 0.57, p =

0.002).

Rainfall and tide heights are shown in Figures 2.4 and

2.5, respectively. Water level and salinity fluctuations for

the east and west culverts are shown in Figures 2.6a and

2.6b, respectively. Water levels increased during the 1990

season at both sites. The increase, however, was greater in

the mud flat area and resulted in the flooding of large areas

of previously exposed mud flats.

The decrease in salinity at the east culvert in 1990

suggests that increasing water levels in the east and middle

lagoons resulted from the coincident increase in rainfall.

These lagoons are connected to Bahia Sucia only indirectly

through mangrove stands. Constant input of runoff into these

lagoons during and after the period of high rainfall may have

prevented inflow of tides and resulted in the apparent lack

of association between water level at the culvert and tide

level (Figure 2.5). In 1991, however, there was less

rainfall. This allowed tides to have a more direct influence







26


10


8

6

4

2


-J
..J
U-LL
z
<
n-


31 30 29 29 28
JUL AUG SEP OCT NOV








Figure 2.4. Rainfall at Cabo Rojo National Wildlife Refuge
(1990).






27


29
SEP


29
OCT


29 29
SEP OCT


28
NOV


28
NOV


Figure 2.5. Heights of high and low tides at Isla
Magueyes in 1990.


H
I
CI
UJ


60-

40-

20-


0
30
AUG


80

60

40

20


O
I-


0 +-
30
AUG


HIGH


80-1






28


0
-J
:U
LUJ
-j
U.J



UJ
I
UJ
u>


60-
EAST I
CULVERT 1
50-
I I

40 /-

30



20- I


10-


0 *
9
SEP 0

WATER LEVEL

60-
WEST
CULVERT
50-


40-


30 -


20 f


10


0 -* i


--"-- SALINITY


9 9 8
SEP OCT NOV
Figure 2.6. water level and salinity at
west (b) culverts in 1990.


100



80


60


z
40


(b)


20


0


east (a) and


100


80


60 C



40


20


0
-J
UJ
:p
UJ
-J
IUJ
I-
III
F
S
UJ
oc






29


on the site, as indicated by fluctuating water levels and

stable salinity (Figure 2.7).

Fluctuations in water level at the west culvert are, not

surprisingly, related to tide cycles (Figures 2.5 and 2.6b).

The dramatic increase in late October 1990, however,

coincided with high rainfall. The increase in salinity at

the west culvert is unexplained. Changes in direction of

water flow were noticed during this time, suggesting that

high salinity water from the west end of the west lagoon may

have moved eastward.

Data from 1986 shown in Figure 2.8 indicate that, in

those areas more distant from sea water inputs, salinity

fluctuates dramatically. Site 1 in Figure 2.8 is located at

the inflow culvert (west culvert). Sites 3, 4, and 5 are

more distant from the culvert and are presumably influenced

by changes in evaporation rates and rainfall.

Figure 2.9 shows total monthly rainfall from 1981 to

1991 at the Cabo Rojo National Wildlife Refuge. Although

there is a clear seasonality of rainfall, there is also

considerable variation among years in the amount of rainfall

for any particular month.







30


EAST
CULVERT







__^- a.-^^^


20
OCT


25
OCT


WATER LEVEL


----- SALINITY


Figure 2.7. Water level and salinity at east culvert
in 1991.


60-


50-


40-


30-


20-


10-


0

LU
UJ



-I
LU
F

LU


-100



-80


p
-60 C



-40



-20



-0


0


15
OCT






31


30-

15-

0-


30 -
15-


I-'


z
=
cJ~


30

15

0
30

15

0
30

15

0


1


....-4~.* !~#4P 4~4.44 I


I I I I I I I I I I I


**44~4~ *


I* I
0* *+"* 4s4W** N


-II I I I I I i






I I I I


+ *4


2




3


4




5


FEB APR JUN AUG OCT DEC


BAHIA SUCIA


Figure 2.8. Salinity measurements from five stations in
Fraternidad system during 1986 (data from Sal de Borinquen,
Inc.)
















M


El


D


40




30




20
z-


z
Rc


Figure 2.9. Monthly rainfall at the Cabo Rojo National
Wildlife Refuge from 1981 to 1991.


32


Average
1990

................ 1991


El


El


a
13


10-10 El


0


0
a


0


5 GQ z CC 5- > 0
4 UJ M wl < 0 U JO
"J LL. ": 0 0 z^ 0






33


Discussion


The dominant abiotic factors likely to affect the

macroinvertebrate community used by shorebirds at the Cabo

Rojo Salt Flats are water level and salinity. The pumps,

dikes, and tidal barriers created by the solar salt company

have resulted in a wide gradient in salinity across the

flats. Salinity patterns at the west culvert were difficult

to reconcile with rainfall and tidal patterns, perhaps as a

result of filling and draining of salt crystallizer basins at

the west end by the solar salt company. Furthermore,

variation in autumn rainfall both within and between years

causes salinity changes and the seasonal flooding and

desiccation of algal mats to occur unpredictably. This poses

a sharp contrast to shorebird stopover areas in higher

latitudes where high-amplitude tidal cycles result in more

predictable patterns. Thus, invertebrate species richness at

the Cabo Rojo Salt Flats is likely to have been truncated by

both the magnitude and the unpredictable timing of

environmental stresses.

Linley (1976) reviewed the biology and ecology of three

important genera of marine ceratopogonids (Culicoides,

Leptoconops, and Dasyhelea), but makes few specific

references to Dasyhelea. There are few accounts on the

ecology of Dasyhelea. Williams (1957) provided observations

on breeding habitats in the Bermuda Islands of several






34


ceratopogonids, including Dasyhelea. Culicoides has been

studied in greater detail (e.g., Magnon et al 1990, Muirhead-

Thomson 1982, Wirth and Blanton 1974, Davies 1967, 1969, Fox

and Capriles 1953), but the extent to which the ecology of

this group can be compared to that of Dasyhelea is unclear.

The biology and ecology of marine corixids were reviewed by

Scudder (1976). Davis (1980) considered some of the

ecological aspects of Artemia and its importance to salt

production.

Corixidae breed year round in tropical environments

(Scudder 1976). Thus, life history characteristics could not

be solely responsible for the increase in abundance of

Trichocorixa in the east and middle lagoons. While some

Trichocorixa are known to tolerate high salinity (Carpelan

1957), Davis (1966) showed that such conditions can retard

the hatching of eggs in T. reticulata the species likely to

occur at the Cabo Rojo Salt Flats. It has been shown that in

addition to having high potential for dispersal by flight,

the migratory tendency of some corixids is related to the

temporary nature of their habitats (e.g., Brown 1951).

However, a majority of the corixids sampled early in the 1990

season were nymphal and thus incapable of flight. It is

possible that either the survival and reproduction of corixid

immigrants or the reproduction of residents increased as a

result of changing water quality conditions. The appearance

of corixid adults in parking lot puddles at the Cabo Rojo

National Wildlife Refuge (1 km away) early in the season






35


suggests that dispersal and reproduction of immigrants may be

important. However, adult Trichocorixa were present in the

deeper areas of both the middle and the east lagoons,

suggesting that reproduction of residents also may be

important. In either case, abundance changes appear to

result from a response to changes in the physical environment

rather than from intrinsic life history patterns or

adaptations. Another observation supporting this conclusion

is that, even at the time when corixids were abundant in the

east and middle lagoons, none were found in the higher

salinity areas to the west.

As in the Corixidae, the reproduction of Dasyhelea in

Puerto Rico is likely to be largely or entirely seasonal.

However, because egg-laying requires wet (but not flooded)

substrata (Linley 1976), the effect of water level

fluctuations on the abundance of larvae may be even more

direct than on other taxa. Furthermore, pupation and adult

emergence of many ceratopogonids can be delayed or prevented

if proper water level conditions are not met (Linley 1976).

In wetlands more directly affected by tides, these conditions

may be met on a predictable basis. At the Cabo Rojo Salt

Flats, however, differences between 1990 and 1991 field data

suggest that the combined influences of rainfall, tide, and

evap-oration result in a somewhat less predictable

availability of breeding conditions for Dasyhelea.

The timing and predictability of invertebrate

productivity is an important aspect of the traditional use of






36


stopover areas by shorebirds. In many stopover areas of the

temperate zone, the biological rhythms of marine

invertebrates bring millions of individuals from regional

populations into reproductive readiness simultaneously.

Within these windows of readiness, environmental cues then

bring organisms into synchronous reproduction. Intrinsic

biological rhythms of invertebrates may be of critical

importance to the seasonal predictability of these areas and

their traditional use by shorebirds. Although the Cabo Rojo

Salt Flats do not exhibit highly predictable bursts of

invertebrate productivity, the site may still be relatively

predictable in comparison to other tropical wetland sites in

the Caribbean.

It appears that calidrid sandpipers use all of the

available habitats at the Cabo Rojo Salt Flats at different

times during the autumn season. In the next chapter, I

examine the rapid responses of shorebirds to changes in their

habitats and how invertebrate resources are exploited.















CHAPTER 3
HABITAT USE PATTERNS BY MIGRATORY CALIDRID SHOREBIRDS


Introduction


Ecologists have made considerable progress in the study

of intertidal invertebrate communities exploited by

shorebirds in temperate latitudes. There have been numerous

studies on the foraging and territorial behavior of

shorebirds, and the effects of invertebrate behavior,

abundance, and distribution on shorebird activity (Bengston

and Svensson 1968, Evans 1979, Goss-Custard 1977a, 1977b,

1984, Myers 1984, Myers et al. 1979, Pienkowski 1983, Puttick

1984, Wilson 1990). Research efforts also have documented

the effects of shorebird predation on invertebrate abundance,

populations or communities, and the potential role that prey

depletion has on the migratory strategies of shorebirds

(Baird et al. 1985, Castilla and Paine 1987, Evans et al.

1979, Marsh 1986a, 1986b, Peer et al. 1986, Piersma 1987,

Quammen 1981, 1984, Schneider 1978, Schneider and Harrington

1981, Wilson 1989). In some cases, cumulative baseline data

have allowed the development of models to estimate metabolic

demands of shorebirds on the benthic biomass of estuaries

(Bildstein et al. 1982, Evans et al. 1979, Grant 1981, Hockey

et al. 1983, Piersma 1987, Piersma and Engelmoer 1982,

Puttick 1980, Smit 1981, Summers 1977, Wolff et al. 1976).

37






38


Of particular relevance to my study are those studies

that document the distribution of shorebirds in relation to

habitat characteristics at the within- and among-site levels

(Brush et al. 1986, Bryant 1979, Goss-Custard 1977b, Goss-

Custard et al. 1977a, 1977b, Hicklin and Smith 1984, Quammen

1984, Wilson 1990, Wolff 1969). Attempts to explain the

spatial distribution of shorebirds have focused on the

behavior and diet of shorebirds and the effects of shorebird

predation on invertebrate communities (e.g., Mallory and

Schneider 1979). In North America, the Bay of Fundy

represents a major migratory stopover where several aspects

of shorebird habitat use have been studied in detail (Gordon

et al. 1985, Hicklin and Smith 1979, 1984, Hicklin et al.

1980, Peer et al. 1986, Richardson 1979, Wilson 1990).

Parallel studies in the tropics, particularly on habitat

use by shorebirds, are scarce (Ashmole 1970, Bolster and

Robinson 1990, Johnson 1979, Robert et al. 1989, Schneider

1985b, Strauch and Abele 1979). Other studies have focused

on migration and competition of shorebirds in the tropics

(e.g., Duffy et al. 1981, Myers and McCaffery 1984, Myers et

al. 1983, Schneider 1985a, Schneider and Mallory 1982, Spaans

1978, Thomas 1987). This scarcity of information is due in

part to the lack of baseline information and suitable

sampling techniques for tropical environments.

Hypotheses and techniques used in studies of shorebird

ecology in temperate estuaries are inconsistent with

observations of tropical estuaries and lagoons, and therefore






39


can not be applied at sites such as the Cabo Rojo Salt Flats.

For example, exclosure experiments have been used to examine

the effects of shorebird predation on invertebrate abundance

and community structure in temperate zone wetlands. Many of

these experiments, which assume there is little lateral

movement of invertebrates into and out of exclosure cages,

have focused on either infaunal invertebrates of coastal mud

flats (Schneider and Harrington 1981, Quammen 1984, Wilson

1989) or sessile invertebrates of rocky intertidal shores

(Marsh 1986a, 1986b). While existing exclosure techniques

may be applicable in tropical intertidal mud flats such as

those in Surinam (Swennan et al. 1982), they are

inappropriate at the Cabo Rojo Salt Flats, where shorebird

feeding often focuses on free-swimming aquatic invertebrates

(this chapter). Shorebirds also feed on aquatic insects (or

aquatic stages of insects) on their arctic breeding grounds

(Baker 1977). Basic information on shorebird feeding ecology

at the Cabo Rojo Salt Flats may therefore benefit future

studies of both tropical and arctic shorebird habitat.

In this Chapter, I present data on numbers of migratory

shorebirds and the distribution of small calidrid sandpipers

(peeps) in autumn of 1990 and 1991. I investigated selection

of foraging sites, at the within- and among-site levels,

under the general hypothesis that calidrid distribution and

density are associated with the availability and density of

prey items (Goss-Custard et al. 1977b, Myers et al. 1980,

Hicklin and Smith 1984).






40


Studies of shifts in the distribution of calidrids among

sites focused on the Fraternidad system. Although

alternative explanations of factors associated with habitat

use focused on the east and middle lagoons and the mud flat,

invertebrate abundance and habitat use in the west lagoon

were also monitored (see Figure 1.2 and site descriptions in

Chapter 1). I treated the eastern and middle lagoons as

equivalent due to their similar area (ca. 19 ha), shared tide

and rainfall inputs (Chapter 1), and because they are

connected by culverts. Alternative interpretations to

account for the distribution and abundance patterns of

shorebirds among selected sites were based on the density and

accessibility of prey. Accessibility is inferred from depth

and water level measurements (i.e., prey in deep water are

inaccessible to calidrids). These alternatives follow:


1. Shifts in the density of preferred prey among sites
accounts for shifts in shorebird distribution. Prey
accessibility (i.e., depth) among sites is similar.


2. Shifts in the accessibility of preferred prey among
sites accounts for shifts in shorebird distribution.
Prey densities among sites are similar.


3. Shifts in both density and accessibility of
preferred prey among sites account for shifts in
shorebird distribution.



I also studied the within-site level of habitat use by

migratory shorebirds. To address this question, I compared






41


resources in patches (=600 m2) of high use and low use by

calidrids within habitat units. This work focused on the

middle lagoon, which harbored the majority of shorebirds at

peak use of the Fraternidad system. Additional work was

conducted in the west lagoon. In the middle lagoon,

substrata seemed less homogeneous than in the west lagoon and

in intertidal mud flats visited at higher latitudes along the

Atlantic seaboard. Therefore, in addition to studies of

invertebrate distributions among patches of high and low

levels of shorebird use, I attempted to relate shorebird

habitat use to the availability of visually quantifiable

wetland substrate types.

The value of the Cabo Rojo Salt Flats as a migratory

stopover depends on its protection and a basic understanding

of the underlying factors influencing habitat use by

shorebirds. The data presented here will contribute to the

hemispheric-wide need to conserve shorebird habitat (Myers et

al. 1987). They will also serve as baseline information to

evaluate the potential impact of habitat management practices

or alterations of the system on migratory shorebird use and

provide a basis for comparisons among similar hypersaline

systems in the tropics. This chapter therefore addresses the

second objective of the project:


Objective 2. To relate the distribution of migratory
Calidris sandpipers to habitat resource patterns at the
within- and among-habitat levels.






42


Methods


Numbers and Distribution of Birds


I surveyed of all shorebird species (Charadrii and

Scolopaci) weekly from 22 August to 15 November 1990,

covering both lagoon systems (Candelaria and Fraternidad).

Jose Col6n (research assistant) conducted these surveys from

14 October 1991 to 25 January 1992. I also surveyed foraging

calidrids in habitat units of the Fraternidad system (see

descriptions of units in Chapter 1) daily from 23 September

to 18 November 1990 and from 14 October to 27 October 1991.

Surveys were conducted between 0700 and 1000 hrs. Numbers of

individuals were estimated using 10 x 40 binoculars. Distant

flocks were counted using a 60x telescope. I used a four-

wheel drive truck to minimize the duration of the surveys,

which adhered to the route shown in Figure 3.1.

I counted small calidrid species (Calidris pusilla, C.

mauri, C. minutilla, and C. fuscicollis) collectively as

calidrids (peeps) due to the similarity of winter plumages

among these species and the large dense flocks in which they

often congregated. Species ratios within this group were

estimated during several counts by myself and by Brian

Harrington (Manomet Bird Observatory, pers. comm.). I

determined the activity of calidrid flocks as either roosting

or foraging. This determination was based on rapid scanning








43


Figure 3.1. Weekly survey route.


. .- . .- . .. . .. . :. -. .-. *. .. . .
. .:" -..., -. ,- ... ....... . .... .. -


. . . . . . . . .

. . . . . . . . .
. : % . : : . : . : : o .o % % .

. .. . .' ." % -. .I~ . . .


.. ....... .. . .". ..





) ..:i .ii .ii ..!:: !!:i :i ii:~ Ffatefnidad



. .....
. . .BS







': "'. "Bahia Sui






44


of each flock rather than rigorous observations of each

individual.

Weekly survey data are expressed as numbers of

individuals per lagoon system. I used linear regression

analysis to examine trends in numbers of calidrids counted

within habitats during daily surveys of the Fraternidad

system. Data for individual units are also expressed as

proportions of all units surveyed to account for changes in

total numbers of calidrids present. Spearman correlation

analysis was used to compare numbers of birds within a

habitat unit to water level and salinity recorded at

measurement stations (east and west culverts).


Shorebird Diet and Foraging Substrata


To confirm that sampled food resources were being used

by migratory shorebirds, I shot ten calidrids in 1990 and

five in 1991 for diet analysis. Stomachs were injected

immediately after collection with formalyn to prevent

posthumous digestion. Each bird was observed foraging before

collection. With the exception of one bird, which was

collected at the mud flat area, all were collected in the

middle lagoon. Additional stomachs of birds wounded from

collision with utility cables between the east and middle

lagoon also were examined (1 in 1990 and 2 in 1991). Artemia

were the only macroinvertebrates found in areas where

calidrids foraged in the west lagoon. It was therefore

considered unnecessary to sacrifice calidrids for diet






45


analysis in these areas. In total, 8 stomachs from C.

pusilla, 5 from C. mauri, and 5 from C. minutilla were

examined. Stomach contents were examined under a dissecting

microscope and identifiable particles were separated into the

following groups: corixid wings; whole corixids; fragments of

Dasyhelea larvae; whole Dasyhelea larvae; fragments of

Dasyhelea pupae; whole Dasyhelea pupae; whole Dasyhelea

adults; whole ephydrid larvae; whole coleopteran larvae; and

whole Mallophaga. Data for each year are expressed as

percent occurrence of each group among all stomachs examined

and as the mean number of individuals (or fragments) per

stomach.

I determined preferred shorebird foraging substrate

(water column vs. bottom) through focal sampling (Altmann

1974). Individual birds were observed and foraging attempts

were counted using tally meters. Unless interrupted, most

individuals were observed for one minute. To avoid repeated

observations of individual birds, only half as many

observations were made from a single flock as there were

birds in that flock. "Water foraging" included foraging

attempts, or "pecks," into the water column or the water

surface; "bottom foraging" included probing, multi-probing,

and scything. A probe is a single peck into the algal or mud

substratum and a multi-probe is a rapid series of probes

discrete in time from other series or activities. Scything

involves movement of the bill from side to side through muddy

or algal substrata. Foraging observations were made in the






46


mud flat area and in the east, middle, and west lagoons. I

used G-tests for goodness of fit (Sokal and Rohlf 1981) to

compare data from different habitat units.


Invertebrate Sampling


I described sampling efforts for the assessment of

among-site distribution patterns of invertebrates in Chapter

2. Within-site invertebrate sampling was paired on the basis

of intensity of use by calidrids (high vs. low). A high-use

patch was defined as an area of 20 x 30 m containing 150-200

foraging calidrids (this 20 x 30 m area often fell within a

larger area used intensively by birds). I then took samples

within the same habitat unit, at least 20 m away, from a

randomly chosen patch of similar depth but of low use (i.e.,

no calidrids). For pairs taken from the middle lagoon, I

recorded the location of patches using a 10 x 10 m alpha-

numeric grid system. The grid system had a total of 1,094

points (alpha-numeric) in an area of 10.9 ha and included

several perimeter areas that never flooded. Grid points not

marked with labeled stakes were located by estimating

distances from marked grid points. The location of samples

within the 20 x 30 m high- and low-use patches was determined

using the protocol illustrated in Figure 3.2, which resulted

in a total of 12 sample sets for each high-use/low-use pair

(six from high-use and six from low-use). Individual samples

were collected and processed as described in Chapter 2.







47


b o d e f g


9


4


*


0


(a)


Figure 3.2. Protocol for high-use/low-use invertebrate
sampling showing three 10 x 10 meter quadrats selected for
sampling on alpha-numeric grid system (a) and two 1 x 1 m
subplots randomly selected in each 10 x 10 m quadrat (b).


5


9
8
7
6
5


9


[--40m-- 10m -M


(b)






48


In 1991, I modified the above sampling protocol because

mud samples often contained few or no invertebrates.

Also,the most prevalent taxa in the stomachs of birds were

rarely encountered in mud samples. I therefore sampled the

water column only, which included the loose algae and

detritus that lies directly over the sediment. Although I

still obtained balanced pairs of six samples from each of the

high-use and low-use patches, additional field time became

available for the collection of samples from deep areas in

the middle lagoon that were inaccessible to foraging

calidrids.

I analyzed data collected for the high-use/low-use study

as well as from other invertebrate sampling studies using t-

tests and analyses of variance. Multiple comparisons were

done using Tukey's honestly significant difference tests. I

made additional post-hoc comparisons between invertebrate

data from different substrata and between high-use/low-use

pairs within substrate types.


Shorebird and Habitat Mapping


I monitored the use of available substrate types by

calidrids in November 1990 entirely within the middle lagoon.

During field observations, more than 80% of the calidrid

sandpipers found in the Fraternidad system were in this

lagoon, a distribution pattern also found in 1991. I

quantified substrate cover by a single visit to each grid

point in the alpha-numeric grid system described above during






49


a seven day period. During each visit, water depth was

measured and total percent cover of five substrate types

(rope algae, shag, amorphous algae, vascular plants, and no

vegetation) was estimated. I characterized each substratum

on the basis of general appearance or by species. Vascular

plants included Salicornia sp., Sesuvium sp., and mangroves

(Avicennia germinans or Rhizophora mangle). In order to

adjust for bottom contour variability, I measured water level

on a fixed depth gauge at the east culvert (Chapter 1, Figure

1.2) at the beginning of each sampling period for comparison

with depth measurements from each point (Figure 3.3).

I mapped calidrid shorebirds between 0645 and 0815 hrs

on 14 18 November 1990 at five-minute intervals.

Observations during these hours avoided confounding effects

of depth fluctuations caused by increasing winds (Brian

Harrington, pers. comm.), usually after 0900 hrs. Some five-

minute intervals were missed on several days. Mapping of

flocks was accomplished with the aid of grid maps and

landmarks. I used a 20 x 60 telescope for reading alpha-

numerically marked grid stakes and for counting birds. Since

birds within flocks were uniformly distributed, it was

possible to express mapping data as sightings per quadrat.

Thus, a grid cell containing a flock at three different

observation times was given a sighting frequency value of

three.

Most of the 10 x 10 meter quadrats contained several

substrate types. It was thus difficult to develop a simple






50


fixed depth station


T
A

1I


grid marker


water level


B


substrate


A + B = relative contour


Figure 3.3. Determination of relative contour for individual
grid points.






51


means of characterizing each of the 1,094 quadrats. To

facilitate analysis of availability of habitat types and

their use by shorebirds, I performed a cluster analysis

(Fastclus Procedure, SAS 1982) to reduce the numerous

combinations of substrate cover and relative contour values

into a manageable number of habitat types. Quadrats that

were more than 50% dry were excluded from the analysis since

birds were not seen foraging in these areas. The cluster

analysis separated the quadrats into 10 habitat types (the

number of habitats was arbitrarily predetermined for the

analysis to allow for aggregation of the five substrate types

into several depth ranges). The Fastclus Procedure uses

nearest centroid sorting methods and Euclidean distances to

cluster data. After separating the quadrats into 10 types, I

used the bird mapping data to determine total number of bird

sightings for each type. An additional analysis was

performed using data from shallow areas only (relative

contour 56 cm), since deep areas are not accessible to

foraging calidrids. Relative contour was then excluded from

the clustering procedure, which was allowed to find five

cluster types. In both the five-cluster and the 10-cluster

analyses, I used G-tests of goodness of fit (Sokal and Rohlf

1981). As recommended by Neu et al. (1974), I determined

Bonferroni confidence intervals for observed proportions of

sightings for each habitat type to minimize Type I error

rates.






52


Results



Numbers and Distribution of Birds


Species encountered during the weekly surveys are listed

in the Appendix. Numbers of calidrids and the distribution

of foraging and roosting birds among the two lagoon systems

during 1990 and 1991-92 weekly surveys are shown in Figure

3.4. In 1990 numbers increased through September with a peak

in early October. In both years, numbers decreased in

November. December and January surveys were done in 1991-92

only and show that considerable numbers of calidrids remained

at the salt flats through this period. Species percentages

determined one week before peak migration in 1990 were as

follows: 70% C. pusilla; 20% C. mauri; 10% C. minutilla; and

1% C. fuscicollis. These percentages were consistent with a

larger data set collected by Brian Harrington (pers. comm.).

C. bairdii was not encountered during ratio estimates

although it was identified once at the Cabo Rojo Salt Flats

during the course of this study (Alfredo Begazo, pers.

comm.).

In the Fraternidad system, the maximum number of

foraging calidrids during the 1990 weekly surveys was 2,538

(x = 1,229, std. dev. = 679). Numbers of foraging calidrids

in the Candelaria system never exceeded 170 during 1990 (x =

61, std. dev. = 65). Although there was a single occasion

during the 1991-92 surveys when numbers of foraging calidrids






53


0 co n u 0 0
NM 0 0 CM CM N
Nme I-Ni
NCm yCol


Fraternidad System


[ Foraging

0T Roosting


1990


00ZZ


Candelaria System


* Foraging

Ea Roosting


I


1991-92




-UM


i .... OM


" M M W M W M
4" WWOUNM


00
-IY-
' -
,rco%



o


000
Il


Figure 3.4. Numbers of calidrids and distribution of
foraging and roosting birds among the two major lagoon
systems during 1990 and 1991-92 weekly surveys.


0
m

z
U-
0

z


3000


2000


1000


0


3


0
z

0
6
z


4000 -

3000-
I

2000

1000 -

0-


b )p 0
00zO
ZZ Q
1a0 ?1-^
CM CM


,i,,,s


essLM






54


was high in the Candelaria system (2,365), numbers were

typically lower (x = 216, std. dev. = 585).

Results of surveys of the Fraternidad system are shown

in Figure 3.5. Data show that, although calidrids used the

east and middle lagoons to some extent early in the 1990

season, a much larger proportion of birds occurred in these

sites later in the season. Moderate numbers of calidrids

occurred in the mud flat area through mid October when

numbers dropped dramatically in this site. The highest

numbers of calidrids were observed in the west lagoon. Dates

of peak counts for each area and results of linear regression

analyses are shown in Table 3.1. The increase in the middle

lagoon and decreases in the mud flat and west lagoon were

significant (Table 3.1). Numbers of calidrids in the mud

flat were negatively correlated with water level at the west

culvert (N = 25, Rho = -0.71, p = 0.001). Although I did not

include the mangrove pool in habitat comparisons, calidrids

used the area early in the 1990 season (maximum count of 790

on 27 September). Throughout the 1991 field season, most

calidrids occurred in the middle lagoon.







55


EAST LAGOON


r0


0


0
IE


0 13


[] B r []_.'"l01^ ,, 1__


1.0


0.8


0.6

0.4


0.2


3


I "i 0.0U


MUD FLAT


_J

0


z


0
t--


LL
0

I-
U-


0
0
a-


0.6-

0.4-


0.2


0.0-


1.01


0.8


0.6


0.4-


0.2-


0

03
]_ 0,.


29
SEP


0.2-


0.0 A
29 28 30
OCT NOV AUG


MIDDLE LAGOON










0El e


WES1
LAKE


r


T
[E


M


0


08


0
0


0


a


13


00
El

El


0


M


0


0


0


0
Q


29 29 28
SEP OCT NOV


Figure 3.5. Distribution of foraging calidrids among
habitat units during 1990 daily surveys.


1.0-


0.8-


0.6-


0.4-


0


0


a


0.0 1
30
AUG


,-. -. -. W -J.t


,w


A x


I






56


Table 3.1. Maximum counts and regression analyses (count vs.
date) on daily surveys of the Fraternidad system.
Slope of
Maximum Date of Regression
Site Count Maximum (d.f.=1) R2 F p
East
Lagoon 465 15 Nov 0.78 0.03 2.03 0.162
Middle
Lagoon 600 18 Nov 4.61 0.29 13.56 0.001*

Mud Flat 405 8 Oct -2.70 0.35 21.30 0.000*
West
Lagoon 3000 9 Oct -15.15 0.20 9.37 0.004*


Shorebird Diet and Foraging Substrata


All birds collected for stomach content analyses were

observed multi-probing. Several invertebrate taxa are

illustrated in Figure 3.6. Data are expressed as percent

frequency of occurrence in Figure 3.7. Corixids

(Trichocorixa) were more prevalent among birds collected in

1990 but were nearly absent in 1991 birds. Conversely,

Dasyhelea larvae (and their fragments) occurred with a much

higher frequency in the stomachs of 1991 birds than in those

of 1990 birds. The same patterns emerge when data are

expressed as mean number of individuals or fragments per

stomach (Figure 3.8).

Individual G-tests for goodness of fit (Sokal and Rohlf

1981) on foraging data from each habitat unit revealed that

only those data from the west lagoon (G = 6.75, n = 31) and

the middle lagoon (G = 23.22, n = 15) were sufficiently





57


~.


1 mm


L


Figure 3.6. Important invertebrate taxa (Trichocorixa,
Dasyhelea larvae and pupae, Artemia). Bill of a Semipalmated
Sandpiper. Trichocorixa adapted from Scudder (1976).
Dasyhelea adapted from Wirth et al. (1977).






58


LU
z 1C
OC
CE 7

0 5
0
- 2
z
CL
0
CE
LU
O,.


1990


0-

5I

0nt


'5


0 LU 0d
z < <


CE 0<0
0 01r
0 0
oQ


LU
z 100-
LU
O-
CC 75-

0
O 50

F- 25-
LU
0 0
CE
LU
C_


CO
-J
Q1


S 0~ 0- 1-, 0C I
< D < < d
M -j -J <
0- < 0 0-
D 0 wi 0
CL < QL -1 -1
S0 -j
Qd <
<0
0


1991


o O
z < < < < < < (

o a -i CL < o- -J -J
o 0 r) 0 w-0
^S0 0^


Figure 3.7. Results of diet analysis of calidrids in 1990
and 1991 expressed as percent occurrence among samples.
CORIX = Corixidae (Trichocorixa); DAS. = Dasyhelea; LAR. =
larvae; FRAG. = fragments; PUP. = pupae; EPHYD. = Ephydridae;
COLEOP = Coleoptera.







59


20



10



0



C0 C
-Z > XLLCo

cc 0 <0
o oi
C
0 0


U
-j


CO










O_
z












-J

CL

cc
UJ
0-

z
z
LU


O OJ 0._
Z < <
SQ



o "
X
cc 0 <
0 C)O


cc
C
Co
ci
0


1990








(5 0- H MCC
< D-j < < 0
CE -J -j <
CL < o 0 I-


< O




1991








(3 CL- M C
< D -J < <

IL < >- 0 I-



C <


Figure 3.8. Results of diet analysis of calidrids in 1990
and 1991 expressed as mean number per sample. CORIX =
Corixidae (Trichocorixa); DAS. = Dasyhelea; LAR. = larvae;
FRAG. = fragments; PUP. = pupae; EPHYD. = Ephydridae; COLEOP
= Coleoptera.


20-



10-



0-






60


homogenous for between-site comparisons of foraging behavior.

Frequencies of water vs. bottom foraging were significantly

different (G = 2722, p = 0.05) between the two units: water

foraging was more frequent in the west lagoon (x = 134 water

foraging attempts per minute; 1 bottom foraging attempt per

minute); bottom foraging was more frequent in the middle

lagoon (x = 0 water foraging attempts/minute, 33 bottom

foraging attempts/minute). Bottom-foraging birds collected

for stomach content analysis in the middle lagoon fed upon

Dasyhelea larvae and Trichocorixa, both of which are most

abundant in the algal substrata lying directly over the

sediments. The most regularly encountered invertebrate in

the west lagoon was Artemia, which was extremely abundant in

the water column.


Invertebrate Sampling


Mean number of invertebrates increased through time in

1990 in the eastern and middle lagoons (Chapter 2). Changes

were attributed to a marked increase in Trichocorixa, at

least in the eastern lagoon. Mean numbers of Artemia

increased in the mud flat area.

For within-habitat comparisons, I collected a total of

228 samples from 17 sets of data (high-use/low-use pairs)

during the study (11 pairs in 1990; 6 in 1991). Of the 1990

pairs, three were collected in the west lagoon and two were

collected in the mud flat area. Data from the middle lagoon

of both years reflect conditions of the invertebrate






61


community during peak use of that area by calidrids. Areas

inhabited by Artemia (west lagoon) were sampled in 1990 only

(during peak use) because calidrids were found exclusively in

the middle lagoon during the shorter 1991 field season.

The results of analyses of variance on high-use/low-use data

are shown in Table 3.2. The differences in mean numbers of

invertebrates per sample between the two seasons are shown in

Figure 3.9. In 1990, mean numbers of Dasyhelea larvae,

Stratiomyidae larvae, and Artemia were higher in high-use

patches than in low-use patches. This difference was

significant for Artemia and Stratiomyidae larvae. Numbers of

Trichocorixa were significantly lower in high-use patches.

In 1991, mean numbers of Dasyhelea larvae and Trichocorixa

were higher in high-use areas but differences were not

significant. When data from both years were pooled, mean

numbers of Dasyhelea larvae were higher in high-use areas but

differences were not significant; mean numbers of

Trichocorixa were higher (not significant) in low-use

patches. Additional samples taken in 1991 from deep areas

had significantly more Dasyhelea larvae and pupae and

Trichocorixa than did high-use/low-use samples taken from

shallow areas.

Dasyhelea larvae and pupae were both significantly more

abundant in "amorphous" algae than in "shag" and "rope" algae

(Table 3.3). Trichocorixa were significantly more abundant

in "rope" algae than in all three other types from which

samples were taken. There were no Stratiomyidae larvae found








62


SII

*) i0)
4H
IM
gcn
0

w C

*O w
I -P
0








4
0








CO u





> 44
I 'H




100
II
.C *






MC





*





*44
(0 r.
0)





mQ
(1) r6










Vu
0



3 U
ig Q









>H w
0
(no

#-






) *H
O Q






>411




MO E
I 0











C144
O3 C
0'


O( H
0Ci
*0 H





*I

u# n
4 *
C IIn








m Q)
CNM



0
CMuE
*IO


II


00
MI
C.'
^7I


0
0




ro
**4






* *xa
No i

t o
t' tnf


C~Ln
o .Cu

LA '


0
0
0

O(N



.* i


rn f-
LA-l -
CM -
'-M'-.


I I



I I



It


0
0
0

C 0
r-o


0 PI
:av CK
wP
r-1 %at


I 4 4 I


0
0
o
0


r-
LA





'-4


o
o
*
0


o0
o0
*1
0


* .1
0 0


* i
0 <-4


0

0

O C4
Ln r-


* e
o





* C


II




II



II


o0
0
* D


LA
*- .C
i-- i-l
LA
'-4
* U
- 4-


00
00
* 1
00


o'-4


m o
. .


0 o 0 0 0
or- o o m o


co m4r% qfn Mn- mlr-q no0


1-1
aMO 004 oo n% C-4
0 oCo LA- o nr- CO a C
* * 1





W 10 W 10 En


CMu
Q )
Q) t


0

.H
$4
Ec;


Cu
80
0


'C

Q)


I -
0 0)
4- 0 >
Cu )


0

o0

0


II


I'

00


I


I


Cu
f*




8
to0 Q) 0


H4



Mf 0 r-4
0

0 al
'0 *-





m .Hg
V U
> Cu 0)
Sea






(1) 0 l
manw
0 0






1 4-
Cu (n-9
CO)

MO~






W
a s<

4O
00
CO2.
44) (0
V 0
0) **Q)
.Q) r31U)
0. 0
,)







0 0
S0
CuO

0.








44
Cu >
W CH












>- 4)-4 :
0c 0







S4H

OHO0
Tge







o *
S0 *r) CO
Cu1 01C r-
(0 3- II

Cu Cu0

0)H Cu^
^4 de
















C H4-
(-90 0) Cu












I


I



I


I






63


1990


* HIGH
M LOW
O DEEP


16


12


8


-J
C
D


z
LL
0
Z
z
z
<
Lu


U OCc CL GC
< < D <
C ~J D.. ~J
Q _. 03 _j
SC CD
< < <
0 CD
oC


UJ C 0- cc
< < D <

X C6 C_ F_
>c 0) 0) F
E o 03m
00
0 Co


Figure 3.9. Mean numbers of individuals in high-use and low-
use patches in 1990 and 1991 (deep areas for 1991 only).
DAS. = Dasyhelea; LAR. = larvae; PUP = pupae; STRAT. =
Stratiomyidae.


Table 3.3. Analyses of variance and Tukey's honestly
significant difference test on invertebrate data from
different substrata in the middle lagoon.
amorph shag rope no veg
__________n=62 n=44 n=25 n=44 p
Dasyhelea
(larvae) x 5.05 2.25 0.20 2.52 0.00
sd 7.78 2.78 0.41 3.37
HSD a bc bc ac
Corixidae
x 2.44 1.23 7.48 2.66 0.00
sd 2.75 2.59 12.89 3.72
HSD a a b a
Dasyhelea
(pupae) x 1.40 0.20 0.20 0.75 0.00
sd 1.94 0.70 0.58 1.24
HSD a b b ab


16


12


8


4


0


4


0






64


in "rope" algae, thus no test was possible. When comparisons

between high-use and low-use patches were restricted to those

samples from within a single substratum (i.e., amorphous

algae), no significant differences were found.




Shorebird and Habitat Mapping


Mean cover values for each habitat cluster are shown in

Table 3.4 (10-cluster analysis). Shorebird sightings were

not distributed according to availability of habitat clusters

(G = 373, p < 0.001). Calidrids used habitat types 4, 6, and

9 less than expected based on availability alone (Table 3.5).

As indicated by mean cluster values in Table 3.4, type 4

consists primarily of shallow areas where algal mats are

absent or poorly developed and which may dry out during times




Table 3.4. Mean percent cover values of substrate types for
each habitat cluster (10-cluster analysis).

Relative Amor-
Habitat contour Rope Shag phous Vascular
cluster (cm) algae algae algae No algae plants
1 7.6 96 1 2 1 0
2 6.9 46 0 52 1 0
3 5.5 1 2 44 52 1
4 4.4 1 2 1 96 1
5 6.2 1 1 90 8 0
6 6.0 0 54 2 44 0
7 6.1 0 51 48 1 0
8 6.7 1 97 1 1 0
9 8.6 46 0 20 34 0
10 8.1 45 48 2 4 0






65


Table 3.5. Simultaneous Bonferroni confidence intervals for
bird sightings among ten habitat cluster types

Expected
Habitat proportion Bonferroni intervals for
type of usage observed proportions
1 0.066 0.059<=0.085<=0.110
2 0.018 *0.027<=0.045<=0.064
3 0.083 0.042<=0.064<=0.086
4 0.130 *0.013<=0.028<=0.043
5 0.209 *0.343<=0.387<=0.430
6 0.043 *0.005<=0.016<=0.028
7 0.029 0.018<=0.034<=0.050
8 0.346 0.277<=0.319<=0.361
9 0.057 *0.002<=0.004<=0.010
10 0.018 0.006<=0.019<=0.031
* indicates significant difference (a=0.05)


of low water levels. Shallow areas also tend to be closer to

edges of the lagoon and birds in those areas may be subject

to greater risk of predation by raptors (personal obser-

vation). The low sighting frequency in habitat type 9 may be

due to greater depth (high relative contour) in these areas.

Types 2 and 5, which had higher sighting frequencies than

expected, are dominated by an amorphous algal formation

typically mixed with detritus particles. While the algae of

this type are not attached to the bottom, they remain close

to the bottom of the water column in a loose aggregate. Type

2 also has a high mean cover value for "rope algae," which is

so named because it lies on the bottom in strands resembling

green rope. The values for expected and observed proportions

of use differed more for the amorphous algal formation (type

5) than for the amorphous/rope algae formation (type 2). The

magnitude of the difference between expected and observed






66


bird sighting frequencies is depicted graphically in Figure

3.10.

When cover values with a relative contour depth of s6 cm

are examined (5-cluster analysis), a G-test (G = 98, p <

0.001) and comparisons of Bonferroni confidence intervals

still reveal rather dramatic deviations from expected

distributions. As in the previous analysis, the type

dominated by amorphous algae (type 5, Table 3.6) had a higher

sighting frequency than expected from availability (Table

3.7), while the type having little development of algae had a

lower than expected frequency. Expected and observed

sighting frequencies for each type are shown in Figure 3.11.





co 400-
z 300

S200
U-
0 100


1 2 3 4 5 6 7 8 9 10
CLUSTER

O Expected U Observed


Figure 3.10. Observed and expected proportions of bird
sightings among ten habitat cluster types.






67


Table 3.6. Mean percent cover values of substrate
each habitat cluster (5-cluster analysis).


types for


Habitat Rope Shag Amorphous Vascular
cluster algae algae algae No algae plants
1 73 3 16 8 0
2 3 8 35 54 0
3 1 1 2 97 1
4 1 4 85 10 0
5 0 92 4 3 0


Table 3.7. Simultaneous Bonferroni confidence intervals for
bird sightings among five habitat cluster types. Habitat
type 1=70% rope algae; type 2=93% shag algae; type 3=94% no
algae; type 4=80% amorphous algae; type 5=100% no algae/65%
vascular plants.


Expected
Habitat proportion Bonferroni intervals for
type of usage observed proportions
1 0.036 0.017<=0.044<=0.070
2 0.179 0.118<=0.167<=0.215
3 0.234 *0.032<=0.064<=0.096
4 0.283 *0.376<=0.441<=0.506
5 0.269 0.226<=0.285<=0.344
* indicates significant difference (a=0.05).






68


3 4 5
CLUSTER


l Expected


* Observed


Figure 3.11. Observed and expected proportions of bird
sightings among five habitat cluster types.


0)
z
U-
O
0

*z


200-


100-


0-


1


2


=.I






69


Discussion

Small calidrids (peeps) were by far the most abundant

birds at the Cabo Rojo Salt Flats during both field seasons.

Of the four species comprising this group, Semipalmated

Sandpipers (C. pusilla) were the most numerous and comprised

the majority of calidrids (=70%) counted during both seasons.

Western Sandpipers (C. mauri) also accounted for a

considerable proportion (=20%) of calidrids counted.

Wunderle et al. (1989) also found that Semipalmated and

Western Sandpipers were the most abundant shorebirds during

autumn migration at Jobos Bay on the south central coast of

Puerto Rico. As is the case at the Cabo Rojo Salt Flats, few

shorebirds pass through Jobos Bay during spring migration.

As suggested by Wunderle et al (1989), shorebirds may

by-pass the Caribbean during northward migration for a number

of reasons that include low invertebrate productivity during

spring at Caribbean wetlands and the ability of birds to

accumulate large fat reserves before departing sites in

northern South America (McNeil 1970). Furthermore, Morrison

(1984) attributes a preponderance of juvenile Semipalmated

Sandpipers at Caribbean sites in autumn to deflection by

trade winds and low flight range capacities of juvenile birds

following departure from North American sites. This

phenomenon would not be expected during northward migration.






70


Calidrids appear to prefer the Fraternidad system for

foraging activity, while roosting often takes place on

crystallizer dikes at the Candelaria system. Although I did

not make habitat comparisons between these two systems, much

of the Candelaria system is deeper than the Fraternidad

system. The greater use of the Candelaria system by long-

legged shorebirds may be related to this difference.

Of the alternative explanations advanced to examine the

distribution patterns among selected habitat units, it

appears that changes in calidrid distribution were due to

shifts in both densities and depth (i.e., accessibility) of

preferred prey in the eastern and middle lagoons versus the

mud flat (alternative 3). Thus, marked changes in the

distribution of calidrids among these habitats in 1990 may be

explained on the basis of physical conditions and

invertebrate food resources.

Early in the 1990 season, prey were equally accessible

in the mud flat and the east lagoons (i.e., both lagoons were

shallow). The middle lagoon was mostly dry at this time.

With the influx of rainfall, there was an increase in the

prey base preferred by shorebirds in the east and middle

lagoons (i.e., Trichocorixa and Dasyhelea). While prey

levels at the mud flat area remained at the same level (and

increased in the case of Artemia), an increase in depth

precluded calidrids from exploiting that area. In areas in

the west lagoon where birds foraged earlier in the season,

Artemia abundance and accessibility remained high (>100






71


individuals per sample). These patterns suggest that when

all sites were accessible for foraging (i.e., low water

levels) calidrids chose the middle lagoon. Although factors

such as water salinity may also directly affect site

selection by calidrids, prey preference appears to be

important.

The possible interaction between prey preference and

accessibility also was noted in 1991 in two habitat units of

Fraternidad. During a full moon high tide, productive areas

in the middle lagoon were unavailable to foraging calidrids

due to high water levels. Water levels in the mud flat area

were relatively unaffected, since a barrier had been placed

in the west culvert by the salt production company. I

observed small flocks of calidrids visiting the middle

lagoon, "sampling" several patches for a few moments, and

returning to the exposed algal mats in the mud flat area

where they pursued adult brine flies (Ephydra gracilis).

After water levels receded in the middle lagoon, calidrids

returned, even while brine flies remained plentiful in the

mud flat area. In the same year, when nearly all of the

calidrids using the Fraternidad system foraged in the middle

lagoon, Artemia were still abundant in shallow waters of the

west lagoon.

I documented the higher quality of deeper areas in 1991

in terms of prey abundance. Invertebrate sampling in these

areas indicated that prey densities were several orders of

magnitude higher than in similar areas in shallower water.






72


This pattern might be due to 1) predator avoidance in the

case of mobile prey (Trichocorixa), 2) differential substrate

quality or flood cycle requirements (Dasyhelea), or 3) prey

depletion, which has been well-documented in temperate zone

estuaries (e.g., Quammen 1984, Schneider and Harrington

1981).

Shifts in diet between years among birds in the middle

lagoon suggest that prey abundance may affect choice of prey

by shorebirds within a site. While the abundance of

Trichocorixa remained high in high-use/low use samples from

1991 (Table 3.2), the diets of collected birds were dominated

by Dasyhelea. The higher abundance of Dasyhelea in 1991 may

have been due to the influence of climatic and tidal

differences between the two years on water conditions in the

middle lagoon (Chapter 2). In 1990, when Dasyhelea were less

abundant, Trichocorixa dominated the diets of birds. Studies

by Schneider (1978) and Wolff (1969) indeed suggest that

shorebirds are numerically selective predators.

At first glance, calidrid distribution patterns at the

within-site level were less clear than at the among-site

level. In the middle lagoon, where most of the effort

devoted to this part of the project was concentrated, strong

significant differences were not found between high-use and

low-use patches for some prey species or when 1990 and 1991

data are pooled. In one instance (Trichocorixa in 1990),

low-use patches had significantly higher prey densities than

high-use patches.






73


Interpretations of high-use/low-use data were elusive

until substrate data were examined. At the outset of the

project, I stratified the within-habitat invertebrate

sampling scheme by use level (i.e., number of calidrids),

depth, and general similarity of the sites. Although

substrate type was recorded for high-use/low-use sampling, in

some cases sampling was conducted across substrates to

maintain depth uniformity and similarity. I did not perceive

the heterogeneous nature of the algal substrate during the

original stratification of sampling effort.

Several clear patterns still emerge from the substrate

data, however, that provide insights into "within-habitat"

patch selection in tropical salt water lagoons. Mapping data

indicated that shorebird distribution was not random. Areas

dominated by amorphous/rope algal substrata were selected by

shorebirds in higher proportion than expected by chance

alone. When the analysis was limited to shallow areas, the

amorphous algae was still selected and the rope algae

formation was selected in proportion to its availability.

These substrate types harbored significantly higher number of

Dasyhelea and Trichocorixa, the most important prey items in

the diets of calidrids. When high-use/low-use samples were

controlled for substrate type, there were no significant

differences for individual taxa. This suggests that prey

abundance was fairly uniform within a given substrate. In

the case of Trichocorixa in 1990, low-use patches sampled for






74


several of the high-use/low-use pairs were located in rope

algae, a substrate type apparently preferred by Trichocorixa.

These findings suggest that foraging site selection by

calidrids may be based on algal substrate physiognomy, rather

than an assessment of infaunal invertebrates (e.g., Goss-

Custard 1977a, 1977b). Because algal formations seem so

important, any significant differences in invertebrate

abundance found in this study between high-use and low-use

patches can not be construed to mean that birds were

perceiving invertebrate distribution. It is possible that

birds more readily perceived and selected substrate

formations.

If migratory shorebirds can visually select "good"

patches, they may be able to meet energetic demands more

efficiently, particularly when foraging bouts are disrupted

by predators. In 1990, predation attempts by Merlins (Falco

columbarius) and Peregrine Falcons (F. peregrinus) were

recorded with a frequency of up to 1 or 2 attempts per 10

minutes. As a result, calidrid flocks rarely remained in any

single area on the grid system for more than 2-3 minutes. In

both seasons at the Cabo Rojo Salt Flats, I regularly saw at

least two Merlins and two Peregrine Falcons. Predation of

shorebirds by Merlins has been well documented at wintering

areas (e.g., Page and Whitacre 1975).

Data from the west lagoon showed clear positive

relationships between Artemia and calidrid distribution.

There is little variation in substrate character in the west






75


lake; high-use and low-use samples were taken within

identical substrata. Calidrids therefore appeared to

actively select foraging sites based on the abundance of

Artemia. To the human eye, patches of greater Artemia

abundance were readily identifiable. Whether or not

calidrids visually assess Artemia abundance is unclear. The

preferred prey in the east, middle, and mud flat areas occur

within lush algal and detrital formations and their abundance

would seem more difficult to perceive visually. When

accessible, however, calidrids moved into these insect-

dominated areas regardless of Artemia abundance in the west

lagoon.

While the substrate types occurring at the study site

likely occur elsewhere in coastal lagoons of the tropics,

additional studies of shorebird feeding activity are needed

in these areas. Questions such as what effect the feeding

activity of extremely abundant corixids (i.e., Trichocorixa)

has on the physical structure of algal substrata (Copeland

and Nixon 1974), how shorebirds use different algal

substrata, and what hydrologic regimes maintain those

substrata and their invertebrate fauna deserve attention in

future studies.















CHAPTER 4
CONCLUSION AND MANAGEMENT RECOMMENDATIONS



I documented the use of habitat resources at the Cabo

Rojo Salt Flats by migratory Calidris sandpipers. Although

the invertebrates fed upon by calidrids are year-round

breeders, proper habitat conditions for invertebrate

productivity are met unpredictably. Calidrids appear to cope

with these changes in their habitat by shifting the target of

their foraging activity and moving between habitats within

the salt flats. In contrast, productivity at stopover areas

in the temperate zone is highly predictable, both annually

and seasonally, and plays a key role in the rigid annual

cycles of migratory shorebirds.

From the perspectives of either shorebird migration or

ecology, it may be inappropriate to compare tropical and

temperate stopover areas. In the absence of a means of

evaluating and comparing shorebird habitats within the

tropics, our knowledge of the extent to which habitat

alterations and loss affect migratory shorebirds will remain

inadequate.

Shorebird conservation groups base their evaluation of

stopover areas on the proportion of a particular shorebird

species occurring at that site at any one time. Areas such

as Delaware Bay in New Jersey and the Bay of Fundy in Canada


76






77


have thus received considerable attention from the research

and conservation community. Our perception of the localized

distribution of many shorebird species is at least partially

affected by their absence from other areas due to habitat

destruction. In Puerto Rico, the conservation significance

of the Cabo Rojo Salt Flats is due in part to wetland losses

elsewhere in the island as well as to the limited extent of

salt flat ecosystems.

Several of the species of shorebirds seen at the salt

flats are distributed among widely scattered mangrove pools

and coastal lagoons throughout the neotropics. These

habitats, however, are only part of a changing landscape

mosaic. In most ecosystems, conservationists and park

managers can rarely expect to maintain all the components of

a naturally changing landscape. To cope with this problem,

it is often necessary to manage different parcels of land in

a relatively static state, thereby arresting "succession."

In Cabo Rojo, lagoons and salt flats formed and might have

persisted without human influence. However, the activities

of commercial salt production over the last two centuries

have likely further arrested change by maintaining the salt

flat and lagoon stages of mangrove succession. Consideration

of this possibility is an important component of habitat

management.

Based on the conclusions of this study, my recom-

mendations for management of shorebird habitat at the Cabo

Rojo Salt Flats follow:






78


1. Partial (but not total) obstruction of tidal
influence in the east and middle lagoons should be
maintained. Under the current hydrologic regime,
salinity stress and desiccation prevent growth of
mangroves. Seasonal freshwater inputs enhance insect
productivity.
2. Part or all of the hypersaline areas in the
west lagoon should be maintained for Artemia (brine
shrimp) productivity. Artemia appear to serve as a
"backup" food supply when productivity is low or
unavailable in the eastern areas.
3. Dikes between crystallizers or similar
structures in the Fraternidad and Candelaria systems
should be maintained as roosting sites for Calidris
sandpipers.
4. Effects of water level and salinity fluctuation
on Dasyhelea (midge flies), Trichocorixa (waterboatmen)
and algae should be studied through controlled
experiments. For example, the existing seasonal cycles
of desiccation and flooding, as opposed to permanent
flooding, may be critical to the maintenance of algal
mats and insect productivity.
5. Manipulation of sea water inputs at the west
culvert should be considered as a means of maintaining
high salinity in the west lagoon and for manipulating
water levels in the mud flat. Temporary exposure of
algal mats in the mud flat may enhance Ephydra (brine
fly) productivity.
6. Habitat requirements of other wildlife groups
and endangered species should be determined and
considered before management plans are implemented.


The Cabo Rojo Salt Flats are of immense conservation

significance on a regional level. Protection of this unique






79


site would benefit many species of resident, migrant, and

wintering shorebirds as well as other important components of

Puerto Rico's wildlife.


9














APPENDIX
SHOREBIRD SPECIES ENCOUNTERED
AT THE CABO ROJO SALT FLATS*


Species

Himantopus
himantopus

Pluvialis
squatarola

dominica

Charadrius
semipalmatus

wilsonia

vociferus

melodus*

alexandrinus

Tringa
melanoleuca

flavipes

solitaria*

Catoptrophorus
semipalmatus

Actitis
macularia

Phalaropus
tricolor*

(continued)


Common Name


Source**


Black-necked Stilt


Black-bellied Plover

LesserGolden Plover


Semipalmated Plover

Wilson's Plover

Killdeer

Piping Plover*

Snowy Plover


Greater Yellowlegs

Lesser Yellowlegs

Solitary Sandpiper*


Willet


Spotted Sandpiper


Wilson's Phalarope*


80





81


Appendix* (continued)

Species Common Name Source**

Numenius
phaeopus Whimbrel

Limosa
haemastica* Hudsonian Godwit

fedoa Marbled Godwit

Arenaria
interpres Ruddy Turnstone

Calidris
canutus* Red Knot*

alba* Sanderling*

pusilla Semipalmated Sandpiper

mauri Western Sandpiper

minutilla Least Sandpiper

fuscicollis White-rumped Sandpiper

bairdii* Baird's Sandpiper* A. Begazo

melanotus Pectoral Sandpiper

alpina* Dunlin*

himantopus Stilt Sandpiper

Tryngites M.
subruficollis* Buff-breasted Sandpiper* Kasprzyk

Philomachus Raffaele
pugnax* Ruff* (1989)

Limnodromus
griseus Short-billed Dowitcher

Gallinago B.
gallinago* Common Snipe* Harrington
* Species not marked with an asterisk (*) were encountered
during weekly surveys (those with an asterisk were seen at
other times).
** Sources are listed for those species not seen during this
study.















REFERENCES


Altmann, J. 1974. Observational study of behaviour: Sampling
methods. Behaviour 49: 227-267.

Armstrong, N.E. 1982. Responses of Texas estuaries to
freshwater inflows. Pp. 103-120 in: V.S. Kennedy (ed.).
Estuarine comparisons. Academic Press, New York.

Ashmole, M.J. 1970. Feeding of Western and Semipalmated
Sandpipers in Peruvian winter quarters. Auk 87: 131-
135.

Baird, D., P.R. Evans, H. Milne, and M.W. Pienkowski. 1985.
Utilization by shorebirds of benthic production in
intertidal areas. Oceanogr. Mar. Biol. Ann. Rev. 23:
573-597.

Baker, M.C. 1977. Shorebird food habits in the Eastern
Canadian arctic. Condor 79: 56-62.

Bengston, S. and B. Svensson. 1968. Feeding habits of
Calidris alpina L. and C. minute Leisl. (Aves) in
relation to the distribution of marine shore
invertebrates. Oikos 19: 152-157.

Biaggi, V. 1983. Las aves de Puerto Rico. Editorial U.P.R.
Rio Piedras, Puerto Rico.

Bildstein, K.L., R.L. Christy, P. de Coursy. 1982. Energy
flow through a South Carolina salt-marsh community.
Wader Study Group Bull. 34: 35-37.

Bolster, D.C. and S.K. Robinson. 1990. Habitat use and
relative abundance of migrant shorebirds in a western
Amazonian site. Condor 92: 239-242.

Brown, E.S. 1951. The relation between migration rate and
type of habitat in aquatic insects, with special
reference to certain species of Corixidae. Proc. Zool.
Soc. Lond. 121: 539-545.

Brush, T., R.A. Lent, T. Hruby, B.A. Harrington, R.M.
Marshall, and W.M. Montgomery. 1986. Habitat use by
salt marsh birds and response to open marsh water
management. Colonial Waterbirds 9: 189-195.


82






83


Bryant, D.M. 1979. Effects of prey density and site
character on estuary usage by overwintering waders
(Charadrii). Estuar. Coast. Mar. Sci. 9: 369-384.

Carpelan, L.H. 1957. Hydrobiology of the Alviso salt ponds.
Ecology 38: 375-390.

Castilla, J.C. and R.T. Paine. 1987. Predation and community
organization on Eastern Pacific, temperate zone, rocky
intertidal shores. Revista Chilena de Historia Natural
160: 131-151.

Chapman, V.J. (ed.). 1977. Ecosystems of the world 1. Wet
coastal ecosystems. Elsevier, Amsterdam. 428 p.

Cintr6n, G., A.E. Lugo, D.J. Pool, and G. Morris. 1978.
Mangroves of arid environments in Puerto Rico and
adjacent islands. Biotropica 10: 110-121.

Collazo, J.A., J. Thomas, A. Knot, and J.A. Colon. 1987.
Preliminary findings on several aspects of the ecology
of Snowy and Wilson's Plovers at the Cabo Rojo Salt
Flats. Caribbean Islands National Wildlife Refuge.
U.S. Fish and Wildlife Service.

Copeland, B.J. and S.W. Nixon. 1974. Hypersaline lagoons.
Pp. 312-330 in: H.T. Odum, B.J. Copeland, and E.A.
McMahan (eds.). Coastal ecological systems of the
United States, Vol 1. The Conservation Foundation,
Washington, D.C.

Danforth, S.T. 1929. Snowy Plovers in Haiti and Porto Rico.
Auk 46: 231-232.

Davies, J.B. 1967. The distribution of sandflies (Culicoides
spp.) breeding in a tidal mangrove swamp in Jamaica and
the effect of tides on the emergence of C. furens (Poey)
and C. barbosai Wirth and Blanton. West Indian Med.
Jour. 41: 39-50.

-----. 1969. Effect of felling mangroves on emergence of
Culicoides spp. in Jamaica. Mosquito News 29: 566-571.

Davis, C.C. 1966. Notes on the ecology and reproduction of
Trichocorixa reticulata in a Jamaican salt-water pool.
Ecology 47: 850-852.

Davis, J.S. 1978. Biological communities of a nutrient
enriched salina. Aq. Bot. 4: 23-42.
-----. 1979. Biological management of solar saltworks. 5th
Int'l Symp. on Salt, Northern Ohio Geol. Soc: 265-268.






84


-----. 1980. Experiences with Artemia at solar salt works.
Pp 51-55 in: G. Persoone, P. Sorgeloos, 0. Roels, and E.
Jaspers (eds). The brine shrimp Artemia. Vol. 3.
Ecology, culturing, use in aquaculture. Universa Press,
Wetteren. 456 pp.

Del Llano, M., J.A. Colon, and J.L. Chabert. 1986. Puerto
Rico chapter in a directory of neotropical wetlands.
Compiled by D.A. Scott and M. Carbonell, IUCN,
Cambridge, and IWRB, Slimbridge.

Duffy, D.C., N. Atkins, and D.C. Schneider. 1981. Do
shorebirds compete on their wintering grounds? Auk 98:
215-229.

Evans, P.R. 1979. Adaptations shown by foraging shorebirds
to cyclical variations in the activity and availability
of their intertidal invertebrate prey. Pp. 8-28 in: E.
Naylor, and R.G. Hartnoll (eds.). Cyclic phenomena in
marine plants and animals. Pergamon Press, Oxford.

-----., D.M. Herdson, P.J. Knights, and M.W. Pienkowski.
1979. Short-term effects of reclamation of part of Seal
Sands,.Teesmouth, on wintering waders and Shelduck.
Oecologia 41: 183-206.

Fox, I. and J. Maldonado Capriles. 1953. Light trap studies
on mosquitoes and Culicoides in western Puerto Rico.
Mosquito News 13: 165-166.

Gordon, D.C., Jr., P.J. Cranford, and C. Desplanque 1985.
Observations on the ecological importance of salt
marshes in the Cumberland Basin, a macrotidal estuary in
the Bay of Fundy. Estuarine, Coastal and Shelf Science
20: 205-227.

Goss-Custard, J.D. 1977a. Optimal foraging and the size
selection of worms by Redshank, Tringa totanus, in the
field. Anim. Behav. 25: 10-29.

-----. 1977b. Predator responses and prey mortality in
Redshank, Tringa totanus (L.), and a preferred prey,
Corophium volutator (Pallas). J. Anim. Ecol. 46: 21-35

-----. 1979. Role of winter food supplies in the ecology of
common British wading birds. Verhanlungen der
ornithologischen Gesellschaft in Bayern 23: 125-146.
-----., R.E. Jones, and P.E. Newbery. 1977a. The ecology of
the Wash. I. Distribution and diet of wading birds
(Charadrii). J. Appl. Ecol. 14: 681-700.

-----., D.G. Kay, and R.M. Blindell. 1977b. The density of
migratory and overwintering Redshank, Tringa totanus






85


(L.) and Curlew, Numenius arquata (L.), in relation to
the density of their prey in South-east England.
Estuar. Coast. Mar. Sci. 5: 497-510.

Grant, J. 1981. A bioenergetic model of shorebird predation
on infaunal amphipods. Oikos 37: 53-62.

Harrington, B.A. 1982. Morphometric variation and habitat
use of Semipalmated Sandpipers during a migratory
stopover. J. Field Ornithol. 53: 258-262.
----. and R.I.G. Morrison. 1979. Semipalmated Sandpiper
migration in North America. Studies in Avian Biology 2:
83-100.

-----., J.P. Myers, and J.S. Grear. 1989. Coastal refueling
sites for global bird migrants. Coastal Zone 89. Proc.
6th Symp. Coastal and Ocean Man., Amer. Soc. Civil
Engineers: 4293-4307.

Hicklin, P.W., L.E. Linkletter, and D.L. Peer. 1980.
Distribution and abundance of Corophium volutator
(Pallas), Macoma balthica (L.) and Heteromastus
filiformis (Clarapede) in the intertidal zone of
Cumberland Basin and Shepody Bay, Bay of Fundy. Can.
Tech. Rept. Fish. Aquat. Sci. 965: 1-59.

-----. and P.C. Smith. 1979. The diets of five species of
migrant shorebirds in the Bay of Fundy. Proc. Nova
Scotia Inst. Sci. 29: 483-488.

-----. and P.C. Smith. 1984. Selection of foraging sites and
invertebrate prey by migrant Semipalmated Sandpipers,
Calidris pusilla (Pallas), in Minas Basin, Bay of Fundy.
Can. J. Zool. 62: 2201-2210.

Hockey, P.A.R., W.R. Siegfried, A.A. Crowe, and J. Cooper.
1983. Ecological structure and energy requirements of
the sandy beach avifauna of southern Africa. Pp. 507-
521 in: A. McLachlan and T. Erasmus (eds.). Sandy
beaches as ecosystems. Junk Publishers, Den Haag.

Javor, B. 1989. Hypersaline environments: microbiology and
biogeochemistry. Springer-Verlag, Berlin. 328 p.

Johnson, O.W. 1979. Biology of shorebirds summering on
Enewetak Atoll. Pp. 193-206 in: F.A. Pitelka (ed.).
Shorebirds in marine environments. Studies in avian
biology, No. 2.

Kline, D.L., R.H. Roberts, and D.A. Focks. 1981. Extraction
of larvae of the ceratopogonid biting midge, Culicoides
mississippiensis, from salt marsh soils with a new agar
technique. Mosquito News 41: 94-98.






86


Lankford, R.R. 1977. Coastal lagoons of Mexico: their origin
and classification. Pp. 182-215 in: M. Wiley (ed.).
Estuarine processes: circulation, sediments and transfer
of material in the estuary, Vol. 2. Academic Press, New
York.

Lee, G. 1989. Population numbers, breeding biology and
habitat use of the Snowy and Wilson's Plovers at the
Cabo Rojo Salt Flats, Puerto Rico. Master's Thesis,
Clemson University.

Leopold, N.F. 1963. Checklist of birds of Puerto Rico and
the Virgin Islands. Agr. Exp. Sta. Bull. 168: 1-169.
University of Puerto Rico. Rio Piedras, Puerto Rico.

Linley, J.R. 1976. Biting midges of mangrove swamps and
saltmarshes (Diptera: Ceratopogonidae). Pp. 335-376 in:
L. Cheng (ed.). Marine insects. North-Holland
Publishing Company, Amsterdam.

Magdych, W.P. 1981. An efficient, inexpensive elustriator
design for separating benthos from sediment samples.
Hydrobiologia 85: 157-159.

Magnon, G.J., D.V. Hagan, D.L. Kline, and J.R. Linley. 1990.
Habitat characteristics and phenology of larval
Culicoides spp. (Diptera: Ceratopogonidae) from a
coastal Georgia salt marsh. Environ. Entomol. 19: 1068-
1074.

Mallory, E.P. and D.C. Schneider. 1979. Agonistic behavior
in Short-billed Dowitchers feeding on a patchy resource.
Wilson Bull. 91: 271-278.

Marsh, C.P. 1986a. Impact of avian predators on high
intertidal limpet populations. J. Exp. Mar. Biol. Ecol.
104: 185-201.
-----. 1986b. Rocky intertidal community organization: the
impact of avian predators on mussel recruitment.
Ecology 67: 771-786.

Matuszeski, W., E. Perez, and S. Olsen. 1988. Structure and
objectives of a coastal resources management program for
Ecuador. Tech. Rep. Ser.: TR-D-2. International
Coastal Resources Management Project sponsored by the
United State Agency for International Developmnent,
between the University of Rhode Island and the
government of Ecuador.

McCandless, J.B. 1961. Bird life in southwestern Puerto
Rico. I. Fall migration. Carib. J. Sci. 1: 3-13






87


-----. 1962. Bird life in southwestern Puerto Rico. II.
The'winter'season. Carib. J. Sci. 2: 27-39.

McNeil, R. 1970. Hivernage et estivage d'oiseaux aquatiques
Nord-Americains dans le Nord-Est du Venezuela (mue,
accumulation de graisse, capacity de vol et routes de
migration). L'oiseaux et R.F.O. 40: 185-302.

Meyerhoff, H.A. 1933. The geology of Puerto Rico.
Monographs of the University of Puerto Rico, Physical
and Biological Series B. 306 pp.

Moreno, J.A. and N. Perez. 1980. Management plan for the
seabirds and shorebirds of Puerto Rico. Puerto Rico
Department of Natural Resources. San Juan, Puerto Rico.
72 pp.

Morrison, R.I.G. 1984. Migration systems of some new world
shorebirds. Pp. 125-202 in: Burger, J. and B.L. Olla
(eds.). Behavior of marine animals. Vol 6: Shorebirds,
migration and foraging behavior. Plenum Press, New
York.

Muirhead-Thomson, E.C. 1982. Behaviour patterns of
bloodsucking flies. Pergamon Press, Oxford. 224 pp.

Myers, J.P. 1983. Conservation of migrating shorebirds:
staging areas, geographic bottlenecks, and regional
movements. Am. Birds 37(1): 23-25.

-----. 1984. Spacing behavior of nonbreeding shorebirds.
Pp. 271-321 in: Burger, J. and B.L. Olla (eds.).
Behavior of marine animals. Vol 6: Shorebirds,
migration and foraging behavior. Plenum Press, New
York.
-----., P.G. Connors, and F.A. Pitelka. 1979. Territory size
in wintering Sanderlings: the effects of prey abundance
and intruder density. Auk 96: 551-561.
-----., J.L. Maron, and M. Sallaberry. 1983. Going to
extremes: why do Sanderlings migrate to the Neotropics?
Pp. 520-535 in: P.A. Buckley, M.S. Foster, E.S. Morton,
R.S. Ridgely, and F.G. Buckley (eds.). Neotropical
Ornithology. Orn. Monogr. 36.
-----. and B.J. McCaffery. 1984. Paracas revisited: do
shorebirds compete on their wintering ground? Auk 101:
197-199.
-----., R.I.G. Morrison, P.Z. Antas, B.A. Harrington, T.E.
Lovejoy, M. Sallaberry, S.E. Senner, and A. Tarak. 1987.
Conservation strategy for migratory species. American
Scientist 75: 18-26.






88


-----., S.L. Williams, and F.A. Pitelka. 1980. An
experimental analysis of prey availability for
Sanderlings (Aves:Scolopacidae) feeding on sandy beach
crustaceans. Can. J. Zool. 58: 1564-1574.

Neu, C.W., C.R. Byers, and J.M. Peek. 1974. A technique for
analysis of utilization-availability data. J. Wildl.
Manage. 38: 541-545.

Nixon, S. 1969. Characteristics of some hypersaline
ecosystems. PhD. dissertation, University of North
Carolina.

NOAA. 1989. Tide Tables 1990, east coast of North and South
America, including Greenland. National Oceanic and
Atmospheric Administration, U.S. Dept. of Commerce.

Odum, H.T., S.W. Nixon, and L.H. DiSalvo. 1971. Adaptations
for photoregenerative cycling. Pp 1-29 in: J. Cairns,
Jr. (ed.). The structure and function of fresh-water
microbial communities. American Microscopical Society
Symposium. Research Division Monograph 3. Va. Poly.
Inst. and St. Univ. Blacksburg, Va.

Ortiz-Rosas, P. and V. Quevedo-Bonilla. 1987. Areas con
prioridad para la conservation en Puerto Rico. Program
Pro-Patrimonio Natuaral. Department de Recursos
Naturales. San Juan, Puerto Rico.

Page, G. and D.F. Whitacre. 1975. Raptor predation on
wintering shorebirds. Condor 77: 73-83.

Peer, D.L., L.E. Linkletter, and P.W. Hicklin 1986. Life
history and reproductive biology of Corophium volutator
(Crustacea: Amphipoda) and the influence of shorebird
predation on population structure in Chignecto Bay, Bay
of Fundy, Canada. Neth. J. Sea Res. 20: 359-373.

Pienkowski, M.W. 1983. Surface activity of some intertidal
invertebrates in relation to temperature and the
foraging behaviour of their shorebird predators. Mar.
Ecol. Prog. Ser. 11: 141-150.

-----. and P.R. Evans. 1984. Migratory behavior of
shorebirds in the western Palearctic. Pp. 73-123 in:
Burger, J. and B.L. Olla (eds.). Behavior of marine
animals. Vol 6: Shorebirds, migration and foraging
behavior. Plenum Press, New York.

Piersma, T. 1987. Production by intertidal benthic animals
and limits to their production by shorebirds: a
heuristic model. Mar. Ecol. Prog. Ser. 38: 187-196.






89


-----. and M. Engelmoer. 1982. Waders and their food
resources: general discussion. Pp. 161-164 in: W.
Altenburg, M. Engelmoer, R. Mes, and T. Piersma (eds.).
Wintering waders on the Banc d Arguin, Mauritania.
Stichting Veth tot steun aan Waddenonderzoek, Leiden.

Puttick, G.M. 1980. Energy budgets of Curlew Sandpipers at
Langebaan Lagoon, South Africa. Estuar. Coast. Mar.
Sci. 11: 207-215.
-----. 1984. Foraging and activity patterns in wintering
shorebirds. Pp. 203-231 in: Burger, J. and B.L. Olla
(eds.). Behavior of marine animals. Vol 6: Shorebirds,
migration and foraging behavior. Plenum Press, New
York.

Quammen, M.L. 1981. Use of exclosures in studies of
predation by shorebirds on intertidal mud flats. Auk 98:
812-817.
-----. 1984. Predation by shorebirds, fish, and crabs on
invertebrates in intertidal mudflats: an experimental
test. Ecology 65: 529-537.

Raffaele, H.A. 1989. A guide to the birds of Puerto Rico and
the Virgin Islands. Princeton University Press, New
Jersey. 254 pp.

-----, and J. Duffield. 1979. Critical wildlife areas of
Puerto Rico. Puerto Rico Department of Natural
Resources. San Juan, Puerto Rico. 97 pp.

Richardson, W.J. 1979. Southeastward shorebird migration
over Nova Scotia and New Brunswick in autumn: a radar
study. Can. J. Zool. 57: 107-124.

Robert, M., R. McNeil, and A. Leduc. 1989. Conditions and
significance of night-feeding in shorebirds and other
water birds in a tropical lagoon. Auk 106: 94-101.

SAS Institute. 1982. SAS user's guide: statistics. SAS
Institute, Cary, North Carolina. 584 pp.

Schneider, D.C. 1978. Equalisation of prey numbers by
migratory shorebirds. Nature 271: 353-354.
-----. 1985a. Migratory shorebirds: resource depletion in
the tropics? Pp. 546-558 in: P.A. Buckley, M.S. Foster,
E.S. Morton, R.S. Ridgely, and R.G. Buckley (eds.).
Neotropical ornithology. Orn. Monogr. 36.

-----. 1985b. Predation on the urchin Echinometra lucunter
(Linnaeus) by migratory shorebirds on a tropical reef
flat. J. Exp. Mar. Biol. Ecol. 92: 19-27.






90


-----. and B.A. Harrington. 1981. Timing of shorebird
migration in relation to prey depleton. Auk 98: 801-
811.
-----. and E.P. Mallory. 1982. Spring migration of
shorebirds in Panama. Condor 84: 344-345.

Scudder, G.G.E. 1976. Water-boatmen of saline waters
(Hemiptera: Corixidae). Pp. 263-289 in: L. Cheng (ed.).
Marine insects. North-Holland Publishing Company,
Amsterdam.

Senner, S.E. and M.E. Howe. 1984. Conservation of nearctic
shorebirds. Pp. 379-421 in: J. Burger and B.L. Olla
(eds.). Behavior of marine animals. Vol 5: Shorebirds,
breeding behavior and populations. Plenum Press, New
York.

-----. and E.F. Martinez. 1982. A review of Western
Sandpiper migration in interior North America.
Southwest. Nat. 27: 149-159.

-----., G.C. West, and D.W. Norton. 1981. The spring
migration of Western Sandpipers and Dunlins in south
central Alaska: numbers, timing, and sex ratios. J.
Field Ornithol. 52: 271-284.

Smit, C.J. 1981. Production of biomass by invertebrates and
consumption by birds in the Dutch Wadden Sea. Pp. 290-
301 in: C.J. Smit and W.J. Wolff (eds.). Birds of the
Wadden Sea. Balkema, Rotterdam.

Sokal, R.R. and F.J. Rohlf. 1981. Biometry. W.H. Freeman
and Company, New York. 859 pp.

Spaans, A.L. 1978. Status and numerical fluctuations of some
North American waders along the Surinam coast. Wilson
Bull. 90: 60-83.

Strauch, J., Jr., and L.G. Abele. 1979. Feeding ecology of
three species of plovers wintering on the Bay of Panama,
Central America. Pp. 217-230 in: F.A. Pitelka (ed.).
Shorebirds in marine environments. Studies in avian
biology, No. 2.

Summers, R.W. 1977. Distribution, abundance, and energy
relationships of waders (Aves: Charadrii) at Langebaan
Lagoon. Trans. R. Soc. S. Afr. 42: 483-495.

Swennen, C.P. Duiven, and A.L. Spaans. 1982. Numerical
density and biomass of macrobenthic animals living in
the intertidal zone of Surinam, South America.
Netherlands J. Sea. Res. 15: 406-418.






91


Thomas, B.T. 1987. Spring shorebird migration through
central Venezuela. Wilson Bull. 99(4): 571-578.

Wetmore, A. 1916. Birds of Porto Rico. U.S. Dept. of
Agriculture. Bulletin No. 326. 140 pp.

Williams, R.W. 1957. Observations on the breeding habitats
of some Heleidae of the Bermuda Islands (Diptera).
Proc. Entomol. Soc. Wash. 59: 61-66.

Wilson, W.H. 1989. Predation and the mediation of
intraspecific competition in an infaunal community in
the Bay of Fundy. J. Exp. Mar. Biol. Ecol. 132: 221-
245.

-----. 1990. Relationship between prey abundance and
foraging site selection by Semipalmated Sandpipers on a
Bay of Fundy mudflat. J. Field Ornithol. 61: 9-19.

Wirth, W.W. and F.S. Blanton. 1974. The West Indian
sandflies of the genus Culicoides (Diptera:
Ceratopogonidae). U.S. Dept. Agric. Tech. Bull. No.
1474: 1-98.

Wirth, W.W., N.C. Ratanaworabhan, and D.H. Messersmith.
1977. Natural history of Plummers Island, Maryland.
XXII. Biting midges (Diptera: Ceratopogonidae). 1.
Introduction and key to genera. Proc. Biol. Soc. Wash.
90: 615-647.

Wolff, W.J. 1969. Distribution of non-breeding waders in an
estuarine area in relation to the distribution of their
food organisms. Ardea 57: 1-28.
-----., A.M.M. van Haperen, A.J.J. Sandee, H.J.M. Baptist,
and H.L.F. Saeys. 1976. The trophic role of birds in
the Grevelingen estuary, the Netherlands, as compared to
their role in the saline Lake Grevelingen. Pp. 673-689
in: G. Persoone and E. Jaspers (eds.). Proc. 10th
Europ. Biol. Symp., Vol 2. Universa Press, Wetteren.

Wunderle, J.M. Jr, R.B. Waide, and J. Fernandez. 1989.
Seasonal abundance of shorebirds in the Jobos Bay
Estuary in southern Puerto Rico. J. Field Ornithol. 60:
95-105.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs