The ecology and vocalizations of Scott's seaside sparrows

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Title:
The ecology and vocalizations of Scott's seaside sparrows (ammodramus maritimus peninsulae)
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xi, 145 leaves : ill. ; 28 cm.
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English
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McDonald, Mary Victoria, 1952-
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Subjects / Keywords:
Ammodramus -- Habitat   ( lcsh )
Sparrows -- Habitat   ( lcsh )
Birdsongs   ( lcsh )
Birds -- Florida   ( lcsh )
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bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1986.
Bibliography:
Includes bibliographical references (leaves 136-144).
Statement of Responsibility:
by Mary Victoria McDonald.
General Note:
Typescript.
General Note:
Vita.

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University of Florida
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oclc - 16109369
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Full Text















THE ECOLOGY AND VOCALIZATIONS OF SCOTT'S SEASIDE SPARROWS
(Ammodramus maritimus peninsula)

















By

MARY VICTORIA MCDONALD


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY



UNIVERSITY OF FLORIDA


1986
























































Copyright 1986

by

Mary Victoria McDonald

















ACKNOWLEDGEMENTS


Since this dissertation is a formal report of my doctoral research,

it would be inappropriate for me to describe all of my ideas and my

feelings over the years--false starts, hunches that paid off, my

occasional discouragement, confusion, and elation, and even the kinship

I felt working with "my" birds on "my" marsh. But these elements were

inextricably woven into my study. What saw me through was not just my

scientific approaches to interesting ornithological questions, but also

determination and good luck, and, most of all, invaluable help from

friends and advisors.

Dr. John William Hardy, my major advisor, steadfastly supported and

guided me through the years. His timely reviews of my work and my

requests for recommendations, his just criticisms, and his flexibility

in allowing me to work independently all significantly contributed to

the success of my graduate career. My other graduate committee members,

Drs. Pierce Brodkorb, John H. Kaufmann, Peter Feinsinger, and Thomas J.

Walker, thoughtfully and generously advised me throughout my project.

Many other faculty members in the Department of Zoology also helped me

greatly.

I am fortunate to have had valuable suggestions from three

ornithologists very knowledgeable about seaside sparrows--Herbert W.

Kale II, Jon S. Greenlaw, and William Post. William Post patiently

helped me get started in my field work at Cedar Key and allowed me to










incorporate some of his unpublished reproductive data and banding

records with my data, as presented in Chapter II of this dissertation.

The Department of Zoology generously supported me with teaching and

research assistantships, equipment, and vehicle use. The Florida State

Museum Bioacoustics Laboratory provided sound analysis equipment and

work space. Other financial support was provided with grants from

several sources: Sigma Xi Grants-In-Aid of Research (1982 and 1983),

Frank M. Chapman Memorial Fund Awards (1983 and 1984), Eastern Bird

Banding Association Research Award (1984), and Van Tyne Memorial Fund

Grant of the American Ornithologists' Union (1984).

John David Wood, Sr., graciously permitted me to conduct my project

on his property near Cedar Key, Florida. The Florida Department of

Natural Resources rangers of the Waccasassa Bay Station near Cedar Key

helped make my sometimes uncomfortable, and always wet and muddy field

work more bearable. Two occasional field assistants, Janine Russ and

David Specht, were genial and as well as adept companions. Thomas A.

Webber also helped me in the field with photography and sound recording.

Many, many other people helped me indirectly over the years. The

support of my parents, Carlyle A. McDonald and Margaret L. McDonald, was

invaluable. And likewise invaluable were the advice and support of many

fellow graduate students. Thomas A. Webber and Linda S. Fink deserve

special thanks--their suggestions, thoughtful and significant criticisms

of my work, and, most of all, their supportive friendships have been

essential parts of my graduate work and life.


















TABLE OF CONTENTS

Page
ACKNOWLEDGEMENTS . . . . . iii

LIST OF TABLES . . . . . . vii

LIST OF FIGURES . . . . . . viii

ABSTRACT . . . . . . x

CHAPTERS

I GENERAL INTRODUCTION . . . . 1

II NATURAL HISTORY AND BEHAVIORAL ECOLOGY OF SCOTT'S
SEASIDE SPARROWS: STUDY TECHNIQUES AND RESULTS . 2

Taxonomy and Morphology . . . . 2
Project History and General Methods . . . 4
Study Site . . . . . 6
General Description . . . . 6
Weather . . . . . 7
Marsh Fauna . . . . . 8
Vertebrate fauna . . . . 8
Invertebrate fauna and seaside sparrow foraging 9
Marsh Flora . . . . . 10
Size and Demarcation of Study Sites . . 11
Reproduction and Reproductive Behavior . . .. 11
Overview of Annual Cycle . . . 11
Annual Cycle of Reproductive Behavior . . 15
Territorial establishment and mating . 15
Nests, eggs, and early development . ... 18
Nesting behavior . . . . 20
Post-breeding behavior . . 22
Productivity, Survival and Reproductive Success . 23
Territories and Territorial Behavior . . 29
Definition and Methods of Determining Territories 29
Description of Territories at Cedar Key . . 29
Territorial Behavior . ............... 30
Reactions to Other Species of Birds and to Humans 32
Discussion of Seaside Sparrow Territoriality . 34
Territory types and variation . . 34
Territory quality and space use . . 35
Extension of territory definition and function 36










III VOCALIZATIONS OF SCOTT'S SEASIDE SPARROWS . . 40

Introduction . . . . . 40
General Methods of Data Collection and Analysis . .. 41
Coverage . . ... . . 41
Sample Size and General Observation Methods . 42
General Analysis of Notes and Recordings . 43
Results and Discussion of Calls and Song . ... 45
Description and Use of Vocalizations . .. 45
Calls of Scott's seaside sparrows . . 47
Primary song . . . 73
Subsong . .o. . . . 79
Countersinging and Repertoire Use .. . . 79
Introduction and comments . . .. 79
Methods of investigating repertoires . .. 82
Results and discussion of repertoire use . 83
Flight Songs: Description and Comparison to
Perch Songs . . . . 84
Description . . . . . 84
Methods of investigating flight song activity 85
Results of singing activity analysis . 87
Discussion of flight songs . .. . 88

IV FUNCTION OF SONG IN SCOTT'S SEASIDE SPARROWS .. . 98

Introduction . ... . . . ... 98
Methods . . . . . 101
Experimental Design . . . . 101
Muting Procedure . . . . .. 106
Statistical Analysis . . . . 108
Results . .. . . . . 109
Voice and Post-Operative Recovery . . .. 109
Mate Attraction and Retention . . 110
Territory Establishment, Retention, and Size Change 119
Behavioral Changes of Muted Birds . . 120
Reaction to Playback . . . . 129
Voice Recovery and Subsequent Behavior .. . 130
Discussion . . . . . 130

V CONCLUSIONS . . . . . 135

REFERENCES . . .. . . . .. 136

BIOGRAPHICAL SKETCH . . . . . 145


















LIST OF TABLES


Table II-1.



Table III-1.


Table 111-2.

Table 111-3.



Table IV-1.

Table IV-2.


Table IV-3.



Table IV-4.


Table IV-5.


Table IV-6.


Summary profile of territoriality and reproduction
of Scott's seaside sparrows at Cedar Key, Florida,
1979-1984 . . . . .

Vocalizations and behaviors measured during time
budget observations . . . .

Vocalizations of Scott's seaside sparrows . .

Characteristics of solo primary singing and
countersinging of 30 mated male Scott's seaside
sparrows during April and May . . .

Experimental design of muting experiments . .

During songless comparison of territory ownership
and size changes for the Mid-Season mutings .

"After song regained" comparison of territory
ownership and size changes for the
Mid-Season mutings . . . .

Behavior changes for individuals, from "Before"
to "During" muted . . . .

Behavior differences comparing Muted, Sham, and
Undisturbed groups . . . .

Sexual selection related to two main song types .





















Figure II-i.


Figure III-1.




Figrue III-2.


Figure 111-3.

Figure 111-4.

Figure 111-5.

Figure 111-6.


Figure 111-7.

Figure 111-3.

Figure 111-9.


Figure III-10.

Figure III-11.


Figure 111-12.


Figure 111-13.


Figure 111-14.


Figure IV-1.


LIST OF FIGURES

Breeding chronology of seaside sparrows at
Cedar Key, Florida, 1979-1984 . .

(A) Audiospectrogram of Tuck call (short notes
8 kHz), and 1 interspersed Tsip call (vertical
(B) Audiospectrogram of Tsip call.
(C) Audiospectrogram of Seeep note . .

(A) Audiospectrogram of male Primary song and
concurrent female Seeep note.
(B) Audiospectrogram of Tchi call . .


Audiospectrogram of Whinny vocalization

Audiospectrogram of Zuck calls . .

Audiospectrogram of Scree calls .

Audiospectrogram of Begging calls from
two nestlings, individuals A and B .

Audiospectrogram of Primary song .

Audiospectrogram of Subsong . .

Audiospectrograms of Countersinging from
individuals A and B . . .

Audiospectrogram of Flight song .

Relationship between time of day and the
of Flight songs/Perch singing . .


around
note).






* .


males,
* *


ratio
* o o


Relationship between wind velocity and the ratio
of Flight songs/Perch singing . . .

Relationship between temperature and the ratio
of Flight songs/Perch singing . . .

Number of Flight songs recorded in early 1983
given by birds of designated mated categories

Audiospectrogram of song of bird ABOR recorded
3 days prior to muting . . ..


viii


. .











Figure IV-2.


Figure IV-3.



Figure IV-4.


Audiospectrogram of "songs" of muted bird ABOR
recorded 5 days after muting . . .

Relative abilities of Muted versus Sham-Operated
and Undisturbed males to attract and retain
females 1983 and 1984 . . . .

Behavioral changes of 21 muted birds Before and
During their songless periods . . .

















Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

THE ECOLOGY AND VOCALIZATIONS OF SCOTT'S SEASIDE SPARROWS
Ammodramus maritimus peninsula

By

Mary Victoria McDonald

December 1986

Chairman: Dr. John William Hardy
Major Department: Zoology

I studied the ecology and vocalizations of Scott's seaside sparrows

(Ammodramus maritimus peninsula) in a Florida salt marsh from

1981-1985. I observed the behavior, vocalizations and reproductive

efforts of 20-30 pairs each year on the 30 ha gridded study site. These

monogamous birds defended all-purpose territories about 1,750 m2 in size

with song and short-distance agonistic behaviors. A high proportion

of males (0.79) returned each year to their previous territories, and

half (0.50) of these remated with their previous year's mates. Although

females initiated about 3.7 clutches of 3 eggs each season, productivity

was low (0.67 fledglings/female/year), because predators destroyed about

80% of the nests. Nevertheless, population numbers remained stable over

the years 1979-1985. The birds' vocal repertoires consisted of a

primary song, three modified primary songs (whispering song, flight

song, and subsong), and 10 calls. Only males sang; they had a song

type repertoire of 2-3 songs. I experimentally investigated the

function of song during the breeding seasons of 1983-1985 by temporarily











muting male birds in the field. I muted birds by rupturing the

interclavicular air sac. Birds remained songless for about 2 weeks but

could give all of their normal calls during this time. I administered

two rounds of mutings, each preceded and followed by time budget,

playback, and other observations on 3 treatment groups: Muted,

Sham-Operated, and Undisturbed birds. The Early muting round tested for

mate and territory acquisition. These Muted birds remained mateless

until they regained their voices; most eventually attracted a mate.

Muted birds acquired territories later than Sham-Operated and

Undisturbed birds. The Mid-Season muting round tested for mate and for

territory retention, and changes in behavior. All Muted birds lost their

mates; a few attracted new mates when they regained their singing

ability. Their territories either shrank or were lost, but new

territories were established (or the original re-expanded) when singing

ability returned. The intensity of close-range aggressive behaviors was

significantly greater for Muted birds than for Sham-Operated and

Undisturbed birds. There were no discernible differences between

Sham-Operated and Undisturbed birds for any of the attributes measured.
















CHAPTER I
GENERAL INTRODUCTION


I studied the ecology and vocalizations of Scott's seaside sparrows

(Ammodramus maritimus peninsula) on a salt marsh near Cedar Key,

Florida, for 5 years. William Post had studied the reproductive ecology

of this population from 1979-1980. In early 1981, I began my

investigations and continued my study through the spring of 1965. The

principal objective of my research was to determine the function of the

vocal repertoire of these birds. During the course of my field work,

however, I observed many aspects of their biology and also collected

reproductive and non-vocal behavioral data.

This dissertation summarizes both my observational and experimental

investigations of the study population. Chapter II is an overview of

the project history, study site, general methods, and the birds and

their biology. Chapter III describes the vocal repertoire and discusses

the probable function of these vocalizations. Chapter IV summarizes the

experiments I conducted in 1983 and 1984, whereby I determined the

function of song in Scott's seaside sparrows.

The information presented throughout most of this dissertation

portrays the behavior of birds I observed and tape recorded with a

minimum of disturbance. The exception, of course, is that Chapter IV

presents results of manipulative experiments. Thus I sometimes make the

distinction between "normal" and "experimentally manipulated" birds.















CHAPTER II
NATURAL HISTORY AND BEHAVIORAL ECOLOGY OF SCOTT'S SEASIDE SPARROWS:
STUDY TECHNIQUES AND RESULTS


Taxonomy and Morphology

Seaside sparrows (Ammodramus maritimus) belong to the "grassland

group" of Emberizine finches (subfamily Emberizinae), which also

includes the genera Ammospiza and Passerculus. The nominate form (A. m.

maritimus) was originally described by Wilson in 1811. Currently nine

subspecies of seaside sparrows are recognized (American Ornithologists'

Union [A.O.U.] 1957, 1973), including the nearly extinct dusky seaside

sparrow (A. m. nigrescens). Beecher (1955) postulated that formation of

the races of seaside sparrows was due primarily to geographic isolation

caused by post-glacial rise in sea level and the concurrent drowning of

river mouths forming bays (also see Funderburg & Quay 1983). All but the

southernmost populations of the nominate race are migratory. The other

races are generally considered to be non-migratory.

Scott's seaside sparrow (A. m. peninsula) was named in honor of W.

E. D. Scott and described in 1888 by J. A. Allen. The type specimen was

collected near Tarpon Springs (Pinellas County, Florida). A. m.

peninsula ranges from Old Tampa Bay (Hillsborough County, Florida)

north to Pepperfish Key (Dixie County, Florida) (A.O.U. 1957).

Austin (1983) and I (McDonald 1983a) have briefly discussed and

annotated the taxonomic history of the seaside sparrow assemblage. The

distinguishing plumage color characteristics of the seaside sparrow

subspecies are thoroughly described and compared by Funderburg and Quay










(1983). Three museums in the United States house good representative

collections of seaside sparrows that I have examined: The American

Museum of Natural History, the United States National Museum of Natural

History, and the Florida State Museum.

Seaside sparrows are generally recognized by their dark gray-brown

head and body (total length about 14 cm), narrow black streaks on the

breast and flanks, yellow lores and wrist spots, and long bills. The

tail is relatively short and narrow and the feet and legs are relatively

large, in proportion to the size of the bird. When flushed, seasides

characteristically fly short distances and then drop back into the marsh

vegetation. Unlike other sparrows, seaside sparrows eat many

crustaceans and insects, but few seeds.

In his original description, Wilson succinctly described seaside

sparrow habits when he said: "Amidst the recesses of these wet sea

marshes, [the bird seeKs the rankest growth of grass and sea weed, and

climbs along the stalks of the rushes with as much dexterity as it runs

along the ground, which is rather a singular circumstance, most of our

climbers being rather awkward at running" (Wilson 1811, p. 68).

Scott's seaside sparrows are among the darkest of the seaside

sparrows. As in other races a certain degree of individual color

variation exists. Some birds approach the lighter colored A. m.

maritimus in shading on the dorsum; others approach the darker A. m.

nigrescens. Early taxonomists made no mention of this color variation,

although Griscom (1944) recognized it. Austin states: "A gradual cline

is evident from the smaller, grayer populations in the south

peninsulaa) to the slightly larger, darker, and dorsally browner birds

in the northwest corner of the range in the Wakulla area (juncicola)"










(Austin 1968a, p. 838). However, W. Post and H. W. Kale (pers. comm.),

most familiar with the morphological variations in the southern

subspecies, agree that there are apparently no characteristics

consistently separating A. m. peninsula and A. m. juncicola (Wakulla

seaside sparrow). The range of juncicola is contiguous with peninsula

near Pepperfish Key, Florida and extends to southern Taylor County,

Florida. Thus, juncicola should probably be merged with peninsula,

which has taxonomic priority.

In all seaside sparrows the sexes are identically colored, but males

are slightly larger. In my study at Cedar Key I routinely took wing

length (wing chord) and weight measurements. For adult males and

females the mean wing chord measurements and 95%7 confidence intervals

were 58.9 (+0.4) mm and 54.0 (+ 0.3) mm; and mean weights 22.5 (+ 0.6) g

and 19.6 (+ 0.7) g, respectively (N=134 males and 78 females). Thus

females were 937o as large as males based on wing chord measurements and

89% as large based on weight measurements. Because the 99'% confidence

intervals for wing chord did not overlap, male and female adults handled

outside of the breeding season could be sexed using wing chord. During

the breeding season the age and sex of birds could more easily be

determined using other criteria. Females possessed a vascular, edematous

brood patch about 1.8 cm wide and males had a cloacal protruberance of

about 2 mm. Fledglings and older hatching-year birds had a

characteristic paler plumage pattern.



Project History and General Methods

The study site near the Gulf coast town of Cedar Key, Florida, was

established by William Post in December 1978. Post investigated the










habitat and reproductive biology of the birds for two years, under

contract with the Endangered Species Program of the Florida Game and

Fresh Water Fish Commission. Information and results obtained from his

project were to become part of a management plan for the rare and

endangered Atlantic coast population of A. m. nigrescens. Post gridded

the marsh with stakes, began color banding of birds, mapped vegetation,

sampled the invertebrate fauna, studied the interspecific influence of

fish crows (Corvus ossifragus) and rice rats (Oryzomys palustris) on

sparrow reproduction, and recorded other descriptive data pertaining to

the morphology and life history (Post 1980, 1981a, 1961b; Post &

Greenlaw 1982; Post et al. 1983; Greenlaw & Post 1965).

Post concluded his field work in the summer of 1980. I accompanied

him to the study site several times early in 1981, and then assumed

responsibility for the study site and birds later in the spring of 1981.

During the breeding seasons (March-June) of 1981-1982 I familiarized

myself with the marsh and the birds' behavior, and continued color

banding adults and some nestlings. I spent an average of 50 days in the

field each of these two years, observing and tape recording

vocalizations.

In 1983 and 1984 I continued comprehensive observations and color

banding of my Florida study population, each year averaging about 70

days in the field from March through June. Behavioral observations on a

field day consisted of 2-4 hours of watching, recording some of the

vocalizations, and describing behavior and territories. I recorded

spoken notes on a tape recorder, and included the location of birds and

activity time (measured with a stopwatch). I later transcribed tapes

and analyzed the data.










The major investigation of my study--temporary song muting--was

conducted during the breeding seasons of 1983-1984 and is described in

Chapter IV. In the spring of 1965 I spent 15 days in the field censusing

returning and new males and conducting playback experiments with female

seaside sparrow vocalizations.

Throughout this report the data designated as having been collected

in 1979-1980 are from Post's unpublished and published work and are used

with his permission. All other data were collected and analyzed by me.

I used non-parametric statistical tests (Siegel 1956; Conover 1980) for

most analyses.



Study Site

General Description

The 30-ha salt marsh study site was north of the Waccasassa Bay of

the Gulf of Mexico. The site was 6 km NNE of the town of Cedar Key, Levy

County, Florida, and within the Sumner quadrangle, USGS Map (29 11' N,

830 00' W). The physical boundaries of the marsh, exterior to the core

gridded study area, were Prodie Creek on the SW, Live Oak Key and

Waccasassa Bay on the S, and Dorset Creek on the NE. The property was

privately owned.

The boundary between the marsh and Waccasassa Bay was not sharply

defined. The shoreline was dotted with oyster bars and many small

islands and was cut by numerous tidal creeks. Except for these creeks,

which ranged from 0.5 to 1.5 m deep at mean high tide, the marsh was

flat. Tides averaged 0.8 m. Most years one or two flooding episodes

occurred during the breeding season, destroying any existing nests of

seaside sparrows. These floods were most often generated by prevailing










winds from the south, driving water in from Waccasassa Bay, combined

with a natural (high) spring tide event. The water level during these

floods usually rose about a meter above mean high tide. Average salinity

measured by Post (1980) at 32 stations on 24 April 1980 was 19.03 + 1.09

0/00.

Weather

Data on cloud cover, air temperature, and wind direction and

velocity were collected at about hourly intervals throughout each field

day. Phenological records such as flowering dates and spring migration

observations were also kept. More complete daily weather information

(maximum and minimum temperatures and rainfall) for all years was

recorded by a National Oceanographic and Atmospheric Administration

(NOAA) station near the town pier of Cedar Key.

My behavioral observations and the handling of birds were carried

out under mild weather conditions (18-33 C, wind <20 km/h) during the

months of February through June. During my 5-year study, however, I did

visit the marsh in all months of the year and under virtually every

weather condition. Temperatures I recorded ranged from 3 C (January) to

l40 C (August). On typical sunny days during the height of the breeding

season (April and May) the mid-morning temperatures averaged 26 C. For

those field days on which I took detailed behavioral observations, the

wind velocity usually ranged from about 2 km/h (just prior to sunrise)

to about 12 km/h by 0900, and then 16-24 km/h by early afternoon.

Prevailing winds were mostly from the southwest. A few sultry field

days were virtually windless. Winds approaching gale force (50+ km/h)

occurred occasionally in the spring and fall.







8


In September 1985, Hurricane Elena touched the Cedar Key area. My

surveys the following week and in 1986 indicated no discernible

population decline in the three bird species breeding on this marsh

(seaside sparrows, marsh wrens [Cistothorus palustris], and clapper

rails [Rallus longirostris]).

Marsh Fauna

Vertebrate fauna

The six-year average population densities of the three resident

bird species were seaside sparrows-2.5 + 0.1 birds/ha, N=253; marsh

wrens--0.6 +0.3 birds/ha, N=23; and clapper rails-0.5 + 0.1 birds/ha,

N=59 (Post 1981a; McDonald 1982, 1983b, 1984, and my unpublished surveys

for 1984 and 1985). In addition to these residents, migratory

sharp-tailed sparrows (Ammodramus c. caudacutus) wintered on the marsh.

They regularly arrived in the last week of September and left 'in the

second week of May. The population density of sharptails averaged about

2/ha. Other bird species seen foraging or resting on the study site

were those commonly found in Florida Gulf Coast salt marshes (Post

1981a; McDonald 1982, 1983b, 1984).

As described below in the section on reproduction, most seaside

sparrow nest losses were attributed to predation, primarily by fish

crows and rice rats. The rice rats dwelt on the marsh. Their density was

about 8/ha (Post 1981b). I also found evidence of predation by

transient racoons (Procyon lotor).

Other species of mammals were occasionally observed: river otters

(Lutra canadensis) played on the bank edges; Atlantic bottlenose

dolphins (Tursiops truncatus) and very rarely, manatees (Trichechus

manatus) swam in the larger tidal creeks. The only reptile I saw on the










study site was the Gulf Salt Marsh Snake (Nerodia fasciata clarki),

observed on three occasions.

Invertebrate fauna and seaside sparrow foraging.

The most obvious and abundant invertebrates on the marsh were

fiddler crabs (Uca rapex) and Gulf periwinkles (Littorina irrorata).

Genoni (1984) reported additional mud-inhabiting invertebrates from this

marsh. Terrestrial invertebrates were also censused previously by

sweep-netting the vegetation during the sparrows' breeding seasons (Post

et al. 1983). By percent of total sample, these were Tettigoniidae

(54.3%), Lycosidae (18.8%), other spiders (7.8%), and Lepidoptera

(Noctuidae and Pyralidae) (3.0%). Six additional invertebrate families

each represented less than 5% of the total sample. Post et al. (1983)

found that 85Y% (by volume) of the nestling's diet consisted of these 10

groups of arthropods.

The invertebrate food species consumed by adults on this marsh are

probably nearly the same as those eaten by Scott's and other subspecies

of seaside sparrows on similar marshes. Howell (1928, 1932), Oberholser

(1938) and Wilson (1811) examined stomach contents of adult Scott's,

Smyrna (A.m. pelanota), Louisiana (A. m. fisheri, and dusky (A. m.

nigrescens) seaside sparrows. In addition to the arthropod groups listed

above, which are known to be fed to nestlings at Cedar Key (and

presumably eaten by adults), these authors found adults had eaten marine

"worms," small crabs and other crustaceans, beetles, dragonflies, flies,

wasps, bivalves, gastropods, and some "weed" and grass seeds. (Audubon

[18311 said that a pie he made of seaside sparrows could not be eaten

due to its "fishy savour," surely attributable to the birds' having

consumed mostly salt marsh invertebrates!)










With the assistance of a biologist familiar with marsh

invertebrates, I examined the stomach contents of eight adult birds from

my study site. Surprisingly, three of the stomachs were virtually empty.

These males had died early in the morning during the breeding season,

perhaps prior to foraging. The other stomachs contained mostly

arthropod exoskeletons (fragments of crabs, insect adults and pupae, and

one small spider), snails (Pyramidellidae and Marginellidae), and

vegetation. Post et al. (1983) presented convincing evidence that food

was plentiful and accessible to the Cedar Key birds throughout the year.

I rarely observed birds drinking. Several times I saw then imbibe

dew from the vegetation, and once I saw a bird drinking and bathing at

the edge of a shallow tidal creek. Although no passerines have salt

glands, seaside sparrows do have the ability to concentrate urine when

consuming salt water (Poulson 1969).

Marsh Flora

Vascular plant species on the study site were described in detail by

Post (1980). In order of relative cover, the major plants were smooth

cordgrass (medium height) (Spartina alterniflora) 38%, black rush

(Juncus roemerianus) 26%o, seashore saltgrass (Distichlis spicata) 23%,

and perennial glasswort (Salicornia virginica) 8%7. There were no woody

plants within the gridded portion of this marsh. Also, there were no

pannes (bare mud areas devoid of vegetation) until September 1985, after

the passage of Hurricane Elena near the Cedar Key region. Apparently

some stands of Spartina were submerged for at least several days during

the storm; consequently these drowning-susceptible plants died.










Size and Demarcation of Study Sites

Post established two contiguous study areas, Cedar Key West ("CKW,"

10-ha in area) and Cedar Key East ("CKE," originally 20-ha in area ).

Although CKW and CKE were contiguous, the study populations of seaside

sparrows living on each site were separated by 200-400 m, and the

populations did not interact. Both study areas were gridded with 2-3 m

high wooden stakes placed at 25 m intervals. Stiff metal prongs on the

tops of the markers discouraged their use by predatory birds. Stakes

were alpha-numerically designated and could be read from at least 50 m.

Additional markers were placed around the peripheries of the study areas

for reference. I concentrated my preliminary observations on the CKW

birds in 1981, then switched to CKE study area (which I enlarged to

30-ha in 1954) for the remainder of my project.



Reproduction and Reproductive Behavior

Overview of Annual Cycle

Fig. II-1 graphically summarizes the reproductive cycle of Scott's

seaside sparrows at the Cedar Key study site. The cycle commenced in

early March with the onset of regular singing by males and subsequent

territorial establishment and mate acquisition. The peak of the breeding

season (as indicated by the number of newly completed clutches) for the

six years 1979-1984 occurred during the second and third weeks in May.

In a typical spring the first clutches were completed around the

beginning of April, and the last clutches by the end of June.

Most clutches (855) were completed by the end of May. Virtually all

breeding and territorial defense activities ceased by mid-June. Both







12


adults and juveniles entered a prolonged molting period during the early

fall and remained difficult to observe until the following early spring.




















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Annual Cycle of Reproductive Behavior

Territorial establishment and mating

Breeding behavior of Scott's seaside sparrows near Cedar Key began

in late winter (February) with sporadic singing of adult males on warm,

windless mornings. Young adult males, hatched the previous spring, also

began to sing imperfect subsongs. By early March all males were singing

typical primary songs, and females began to associate with males.

Females solicited male affiliation with the "whinny" and "tchi" calls

(Chapter III).

During these early weeks of the season, weather influenced the

intensity of singing and other observable breeding activities. Wind

velocities greater than 25 km/h accompanied by temperatures less than

200 C caused a nearly complete cessation of overt territorial and mating

behaviors. Mild weather, even in early February, greatly enhanced

regular singing activity and behavioral interactions. In addition to

this immediate influence of atypical weather, prolonged cool

temperatures delayed the onset of breeding within a given season, and

hot weather in late May caused an early cessation of breeding

activities. The early spring of 1963, for example, was unusually cold:

average daily temperatures for March were about 50 C below normal

throughout mid-Florida. The breeding activities of the study population

at Cedar Key were about 2 weeks delayed that year-I did not find a

completed clutch until 26 April. On the other hand, the unusually warm

February of 1985 certainly must have accounted for my finding fledged

seaside sparrows on 16 March and fledged marsh wrens on 23 February,

both record early nesting dates for these species for any known breeding

locality.










Most males re-established the same territories from year to year and

vigorously defended these during March and early April, the period when

the most fervent territorial disputes between first-year and older

adults and between residents and floaters broke out. By May territorial

ownership and boundary disputes were rare, seemingly occurring only when

floaters attempted (always unsuccessfully) to take up residence on an

occupied territory. The intensity of singing (as measured in minutes of

singing/hour) also declined gradually after a peak in early April. By

June there was only sporadic singing activity occurring daily from just

before sunrise to about one-half hour after sunrise.

Most birds paired by mid-March. The mates remained paired over the

remainder of the breeding season. I never observed a natural incidence

of divorce, although Werner (1975) reported several instances of

re-pairing in his Cape Sable birds in the same breeding season. Seven

percent of 97 non-experimental territorial males remained bachelors

throughout the breeding season in my study. Werner (1975) reported that

about 12% of his 111 Cape Sable seaside sparrows were bachelors.

Apparently the adult sex ratio of the breeding birds was slightly skewed

in favor of males. Although Post (1980) assumed that most unmated

territorial males were probably first year birds, my longer study of

these marked birds indicated no significant difference in the

proportions of unmated older territorial birds and unmated first-year

territorial birds (X2=0.4, N=10 bachelors, df=l, P>0.5).

My observations over the years also suggested that returning males

tended to re-mate with their female of the previous year, if she also

returned the second year. I documented mate retention using data for

non-experimental males and females present in both 1963 and 1984, the










years for which I had the most complete data. Of the 10 cases in which

both members of the pairs were present in succeeding years, there were

five re-mates. Mate retention from year-to-year also occurs in northern

seaside sparrows on Long Island, New York (Jon Greenlaw, pers. comm.).

Werner (1975) also stated qualitatively that there was some degree of

year to year mate retention in his Cape Sable seaside sparrow subjects.

Females solicited copulations with a slow, low-pitched variation of

the "whinny" vocalization accompanied by quivering bilateral wing

raises. This display was given at ground level with the bird concealed

in the marsh vegetation. A nearby male (usually the mate) was

immediately attracted to this enticing behavior and would quickly

copulate by mounting the female briefly with fluttering wings and then

bounce off, landing several meters away. The male sometimes gave one or

two songs immediately after copulation, whereas the female was almost

always silent afterwards.

Typical bouts of copulation involved three to five mounts during

time intervals of 0.5 to 1.5 hours. All of the copulation bouts I

observed occurred in the mornings. During this period the female

sporadically gave her solicitation whinny, while the male remained

within a 15 m radius of her and sometimes sang. Of the 96 copulation

bouts I observed under non-experimental conditions, all but three were

between birds I had previously known or subsequently knew to be mates.

On the remaining three occasions I observed neighbor or floater males

sneak in and copulate with a soliciting female while the mate was

vigorously singing or confronting other birds on the opposite side of

his territory.










Nests, eggs, and early development

Although this was primarily a behavioral study, nesting and other

reproductive data were routinely collected during the breeding seasons

of 1981-1904, and in some cases were consolidated with Post's

1979-1980 data.

Seaside sparrow nests are notoriously difficult to find in salt

marshes. My early efforts to find nests by dragging a chain through the

vegetation, by trying to flush nesting females by walking transects, and

even by using a bird dog were largely unsuccessful. I eventually

learned to locate most of the nests of subject birds by close

observation of the parents.

For all nests I found, I noted date and time of discovery, parents,

location relative to the grid system and territorial boundaries, and

vegetative microhabitat. Because I wished to minimize human

interference, I handled only a sample of the nests and nestlings that I

was aware of. The additional information taken for these sample nests

was form of nest cup (open or domed), height from ground to bottom of

cup, dimensions of cup (inside and outside diameter, inside and outside

depth), material used in constructing nest, number of eggs or

hatchlings, egg dimensions, hatchling weight (for 11 individuals), age

of hatchlings, and daily survival. I also weighed seven nests collected

after fledging.

The following summarizes my descriptive data on 194 nests. Two

nests had well-defined domes and entrances. I detected no preferred

directional entry pattern of attending parents for any of the nests,

although the nests of some subspecies of seaside sparrows are mostly

domed and have distinct entrances. About half of the nests were built










in Distichlis and the remaining roughly split between Salicornia and

Juncus microhabitats. All nests were constructed primarily with the

Distichlis grass; a few had small Spartina leaves woven in. The average

height of the nest (as measured from the ground to the bottom of the

nest cup) was 35 cm. Average nest size measurements were: outside

diameter of cup 9.3 cm; inside diameter of cup 5.4 cm; outside depth of

cup 5.3 cm; inside depth of cup 3.3 cm. Also in contrast to other

subspecies, at Cedar Key the average clutch size was smaller (3.02 +

0.17 eggs, N=194 nests), compared to about 3.65 in New York (Post et al.

1983).

Average egg dimensions were 20.6 mm X 15.7 mm (N=35), and egg

weights averaged about 2 g. While exhibiting minute individual

variation, the color pattern of the eggs was essentially the same as

described for seaside sparrows in detail elsewhere (Austin 1966a).

Egg and nest cup dimensions for Scott's seaside sparrows at Cedar

Key were within the ranges reported for other subspecies in the

literature (Austin 1968b; Norris 1968; Sprunt 1966; Trost 1966;

Woolfenden 1968; Werner 1975; Greenlaw pers. comm.) and in collections I

measured at the American Museum of Natural History, the United States

Museum of Natural History, and the Florida State Museum.

I categorized nest placement within a pair's territory as "edge" or

"center." An edge nest was so designated if it was built in the outer

fourth of the total area of the territory. I found no significant

difference in the birds' tendencies to locate nests at the territory

edge versus towards the center (X 2=0.7, N=194, df=l, P>0.4).

Only 116 nestlings were directly observed, but others were known to

be in active nests. The young remained in the nest 9-11 days. Their










weights increased from 2.2 g on Day 0 to 15.1 g on Day 10. The few

other morphological data I took on these birds agree with Werner's

(1975) extensive quantitative morphological data and photographs of

nestlings taken days 1-8 for Cape Sable seaside sparrows.

Norris (in Austin 1968a) gave a detailed description of nestling

Louisiana seaside sparrows (A. m. fisher) and the behavior of the young

and their parents. My observations of Scott's seaside sparrows at Cedar

Key are very similar to Norris's in Louisiana.

resting behavior

Nest building (by the female only) began on the day of or the day

after copulation bouts. Females did not re-use nests, but built a new

nest for each new clutch. The female usually completed building her

nest within a day and laid her clutch of three eggs (rarely four) over

the next five days. The eggs were laid one a day, at any time during the

day. Infrequently females that were building nests, laying, or

incubating, would copulate with their mates. Incubation was by the

female only, for 11-12 days.

Most years the first young of the season hatched around the second

week in April (Fig. II-1). All of the young hatched within 24 hours and

began to gape and utter soft "peeps" on the day of hatching. The eyes

were fully opened by day five and at about this time the begging

vocalizations changed from a "peep" to a "churp" and became more

intense. Some nestlings fledged and were able to run about as early as

Day 9. Most began short flights about Day 13.

The hatchlings remained in the nest for 9-10 days and were fed by

both parents. The combined average feeding rate was 3.2 visits per

hour. Parents also maintained a clean nest by removing fecal sacs. Post










et al. (1983) determined the diet of hatchlings older than 3 days by

placing pipe-cleaner ligatures around their necks and then removing the

food from the young or the nest cups after an hour had elapsed. The

most important food groups for the nestlings were found to be the

insects of the taxa Tettigoniidae and Lepidoptera and spiders of several

families. These invertebrates constituted 85% of the nestlings's diet.

Both parents continued to feed the young for 15-20 days after

fledging. If the breeding season had not progressed too far (i.e. prior

to about 15 May), a female with fledged young would begin to renest

about a week after the first brood had fledged and would leave the care

of fledglings to her mate. I noted five such cases in 84 pairs.

Since most nests were destroyed before young fledged, seldom did a

pair actually have the opportunity to rear a second brood within a

season. From late March through early June, unsuccessful parents would

try repeatedly to raise a family. The average number of nesting attempts

per season of 84 pairs (1981-1984) was 3.7, and the interval between

nest destruction and renesting was 5.7 days. In 1984 I observed one

pair attempt seven nests, all unsuccessful.

Fathers began to avoid their first brood after tending their

fledglings for about three weeks, or after their second successful

clutch hatched. They chased their fledglings (as well as any other

juveniles) off the parental territory and started to devote their

attention to their new brood. After nesting had stopped family groups of

fledged, dependent young and their parents were often observed during

the months of June and July. Adults without families were seldom seen

during this period, especially during the hot daytime hours.










Post-Breeding behavior

By August most juveniles were independent and began to form loose

groups of about three to eight. Sometimes adult males associated with

these groups, which persisted through October. Juvenile males gave

occasional bouts of imperfect subsong in August and September, and

rarely through the winter. Although present (as evidenced by occasional

mist net captures), adult females were rarely seen in summer.

From late September through October there was a resurgence of easily

observable but essentially non-vocal behavior, such as foraging and

territorial defense. From these observations and my intensive mist

netting in the fall of 1982 and 1983, I concluded that adult males and

females remained within a radius of about 250 m of their previous spring

territory throughout the year. Juveniles appeared to wander a great

deal more, perhaps as far as several km.

Little is known regarding the fate of the fledgling seaside sparrows

at Cedar Key or elsewhere. Of the total of 98 hatchlings and fledglings

Post and I banded at Cedar Key, I recaptured only 4 during my intensive

netting 1982-1984. Presumably the emigration and general mobility of

fledglings as well as of non-territorial older birds are mechanisms for

the birds' locating and colonizing any unoccupied territories and viable

habitat.

The Cedar Key population appeared stable (average density 2.5

birds/ha) throughout the 7 years 1979-1985. Adult birds with territories

were relatively long-lived. By the end of 1984, I had studied subject

males from 1 to 4 years. According to banding records, two males were at

least 5 years old, and one was at least 6 years old.










The adult post-nuptial molt (and only annual molt) of their nuptial

plumage began in early July, and the post-juvenile molt began in late

July. Both molts were completed by October.

The seasonal weight variation was slight but significant. Both

sexes were heavier in winter than in summer, but the difference was not

as great as in the nominate migratory seaside sparrows (Post 1980).

Productivity, Survival, and Reproductive Success

I summarized parameters of reproduction for seaside sparrows at

Cedar Key in Table II-1. The data combine my unpublished observations

(1981-1984) with Post's observations (1979-1980), as given in Post

1980 and Post et al. 1963.

Post (1981b) intensively studied seaside sparrow reproduction and

factors that affected productivity during his 1979-1980 project. He

also compared these characteristics of reproduction in A. m. peninsula

to another well-studied population, A. m. maritimus in New York (Post &

Greenlaw 1982; Post et al. 1983). I combined the two years of Post's

data with reproductive data I collected 1981-1984.

Studies of nest productivity should consider whether nest failures

are due to human disturbance. I did not test if my visitations affected

the nesting success I observed. Post (1980), however, did test for an

observer effect using the methods of Mayfield (1975) and Johnson (1979)

and found that the frequency of nest visitation did not affect nesting

success of Scott's seaside sparrows.










Table II-1. Summary profile of territoriality and reproduction
Scott's seaside sparrows at Cedar Key, Florida, 1979-1984


Territories, Mating, and Return Ratesa
Mean territory size
Ecological density of territorial males
Mean annual return of territorial males
Proportion of re-mates
Proportion of bachelor territorial males
Ratio unmated first year/older males0
Mean length of study of male in population

Productivity and Survivala,c
Mean clutch size (C)
Mean no. clutches initiated/female/yr (I)
Probability of egg producing fledgling (S)
Productivity (fledglings/female/yr)
Mean length of breeding season
Proportion of nests producing fledglings
hest success ratio of young/older breeders
Adult annual survival male return) rate
Juvenile survival rate
Production of fledglings->breeders next yrb


1759 + 242 m2
2.5 males/ha
0.78 males/yr
0.50
0.07
4/6 N.S.
2.3 yr


3.02 + 0.17
3.7
0.06
0.67
95 days
0.06
3/5 .S.
0.78
0.67
0.45/female/yr


Combined data from Post 1980; Post et al. 19b3; and author's
unpublished observations. Probability level: h.S.=P>0.05.
bSee text for explanation of calculations.


cBased on 194 nests










At Cedar Key the probability that a nest would produce fledglings

was remarkably low, but because females renested within 7-8 days of nest

destruction, the population seemed to have remained stable from 1979

through 1985. That is, bird density remained about the same over the

years we censused the study population (Post 1980, 1981a; McDonald 1982,

1983b, 1984, and my unpublished data).

Post et al. (1983) calculated probability of an egg's surviving 21

days (through the egg and nestling period) and producing a fledgling to

be only 0.06 (Post et al. 1983). This contrasts with an egg survival

rate of about 0.35 in New York.

Of a total (McDonald and Post) sample of 194 nests whose fates were

carefully documented, only 12 (6>7) produced at least one fledgling. The

major causes of nest mortality at Cedar Key were flooding, and predation

by fish crows and rice rats. Eight (4%) of the nests failed due to

desertion. Neither Post nor I ever suspected hatchling death due to

starvation. I found only a few instances of partial nest mortality.

Eleven (2%) of the 473 eggs I observed in the field failed to hatch and

were presumably infertile.

Destruction by flooding accounted for the mortality of 17 (9%) of

the nests. Normal tidal fluctuations in water levels seldom reached the

bottom of the nest cup (about 35 cm above the ground). However, in most

years at least one major unpredictable flooding of the marsh occurred.

For the seven years (1979-1985) there were nine such floods during the

breeding seasons.

Predation by fish crows destroyed 37 (19") of the total nests. Fish

crow predation was assumed when eggs disappeared without leaving shell

fragments or a disturbed nest (indications of mammalian predation). Fish










crows were about three times more likely to prey upon nests with

hatchlings than on those with eggs.

Post (1981b) concluded that nesting in Juncus should be preferred by

the birds because Juncus stands were less likely to be flooded and

because this vegetation provided cover protection from fish crow

predation. However, rice rats on the marsh apparently discouraged

seaside sparrows from nesting more in Juncus by destroying their nests

(Post 1981b). The birds were found to nest more frequently (857 of the

total nests) in less dense Distichlis and Salicornia, even though nest

failure was more likely to occur in these vegetation types, as compared

to failures in Juncus (Post 1981b).

The remaining 120 (624) of the total nests were destroyed by rice

rats and unknown predators (probably racoons).

Post (1961b) tested whether rice rats were actually destroying nests

by placing tin cylinders around nests. These were open at the top,

allowing entry by parents and aerial predators but excluding small

mammals. Forty-eight percent of 42 experimental nests with this

protection produced fledglings, whereas only 6%a of the 34 control

(unprotected) nests had young that fledged.

To summarize: about 80% of the nests at Cedar Key were destroyed by

predation. This contrasts with findings in New York where fewer seaside

sparrow nests were destroyed by predators and more losses (about 65% of

the total nest mortality) were due to flooding or rains, desertion,

hatching failure, and unknown causes (Post et al. 1983).

I report productivity as the number of fledglings/female/year.

Post's data (1980) were combined with mine: Post observed 109 clutches,

and I observed 85 clutches. Productivity was determined by the method










of Ricklefs and Bloom (1977): Productivity = Mean Clutch Size (3.02) X

Probability of Egg Success (0.06) X Number of Clutches Initiated by a

Female/Year (3.7). (The term "productivity" and its values are roughly

equivalent to the "realized specific natality rate" parameter that is

conventionally calculated using life table data.) The six year average

productivity for 1979-1984 was 0.67 fledglings/female/year. This value

contrasts with the much higher rate of 4.25 for the New York population.

New York females produced about six times as many young within their

average 75 day breeding season as the Florida birds did in their average

95 day season. The annual survival, however, was lower in New York

(Post et al. 1983).

I determined the adult annual survival rate at Cedar Key to be about

0.78, based on the return of 51 of 65 adult males over the years

1980-1983 and assuming a roughly equal sex ratio. This figure represents

a minimum value, since some birds may have emigrated. This is a

relatively high value for a small Passerine bird. Werner (1975)

estimated a 0.88 survival rate for the likewise non-migratory A. m.

mirabilis, based on a one year return sample. Adult survival is lower

for migratory A. m. maritimus--only about 0.45 (Post 1974).

I estimated the juvenile survival rate to be about 0.67. This figure

was determined using the method of Post et al. (1983) and using their

estimated ratio of juvenile/adult survival (0.85, as determined from

returns of banded nestlings and adults). Thus, I multiplied the adult

annual survival rate of 0.78 by the ratio of juvenile/adult survival of

0.85, giving 0.67.

Although I did not have enough data to directly calculate net

reproductive rate (R0) using life table parameters, I suggest that the










Cedar Key population of seaside sparrows is maintaining its numbers for

the following reasons: First, there was no decline in population

density over the years. Additionally, my experiments in 1983-1964

demonstrated that floaters (itinerant males without territories or

mates) were always available to take up residence on territories they

perceived as unoccupied. Secondly, the reproductive data I do have

suggest that enough juveniles were produced and survived to replace

non-returning adults. That is, using my calculated productivity figure

of 0.67 fledglings/female/year and Post's (1980) juvenile survival rate

of 0.67, each breeding female (pair) produced 0.45 first-year birds.

Assuming a sex ratio of about unity, each female produced 0.225

first-year female breeders. If the minimum adult annual survival rate

was 0.78 and applicable to both sexes, then the annual adult female

mortality rate was 0.22 (1.00 0.78 = 0.22) or less. Since 0.225 is

about the same as 0.22, these reproductive data do substantiate my

observation that the population size has been constant over the years.

Post et al. (1963) calculated a net reproductive rate of 2.72 for the

increasing New York population. The authors also state that the net

reproductive rate for the Cedar Key population was 1.11 (based on

1979-1980 data), but it is unclear how this figure was determined

without life table (i.e. survivorship) data.

These New York and Florida projects are the only major long-term

studies that report and summarize detailed reproductive data. Other

papers that contain some data on breeding success and productivity for

other subspecies of seaside sparrows are Nicholson (1946), Woolfenden

(1956), Stimson (1956), Norris (1968), Sprunt (1968), Stimson (1968),

Trost (1968), Woolfenden (1968), Worth (1972), and Werner (1975).













Territories and Territorial Behavior

Definition and Methods of Determining Territories

The working definition of "territory" I used in this study was "any

defended area" (Noble 1939, p. 267). My use of the term "defended"

implies that a bird exhibited aggressive behavior towards another, with

the seeming intention of driving or keeping the other out of his or her

territory. I considered vocalizations and visual displays directed at

another bird to be defensive behaviors. This study dealt primarily with

aspects of male territoriality, although female seaside sparrows also

exhibited territorial behavior. I considered a territory to be an area

in which a male invariably challenged intruders with singing, displays,

or other overt aggressive behaviors.

All of my behavioral observations were made relative to the grid

markers. I drew territory maps for the entire study population weekly,

by connecting the points of the most peripheral singing perches with

lines. I traced the territories thus delineated with a compensating

polar planimeter and then calculated the enclosed areas. When a map

indicated a boundary had moved by 15 m or more, I considered that to be

a territorial boundary shift. The summary information regarding

territory sizes and location reported in this chapter were those

measured for non-experimental birds during the first week of May unless

indicated otherwise.

Description of Territories at Cedar Key

Territories at Cedar Key were all purpose--used for mating, nesting,

and feeding. Mated pairs exclusively occupied territories throughout

the breeding season, although boundaries between territories fluctuated.










Only two instances of complete territory relocations were noted for 65

non-experimental males studied 1979-1982.

The mean yearly return rate for male territorial birds was 797%

(N=89). There was a strongly significant tendency for males to

re-establish territories on the same sites in succeeding years. (My

conservative null hypothesis was: Returning males are as likely to

establish a new territory as they are to re-establish their old

territory. My sample sizes and statistics were: 43 re-established

territories of 52 observed returnees; X2 one-sample test, X2=21, df=l,

P<0.001). Year-to-year retention of territories has also been reported

qualitatively in the few other studies of marked populations of seaside

sparrows (Worth 1972; Werner 1975; Greenlaw pers. comm.).

The territory sizes of non-experimental birds at Cedar Key ranged

from about 200 to 4000 m2. The mean size was 1759 m2 (SE=242 m2, N=65).

This average territory size for the population did not change

significantly over the years 1982-1984 (Kruskal-Wallis one-way ANOVA,

N=43 territories of non-experimental males, df=2, H=0.83, P>0.5). In

comparing the individual males' territories from year to year, I found

no significant increase or decrease in their territorial areas (Wilcoxon

matched-pairs signed-ranks test, N=23, T=91, P>0.05).

The boundaries of territories did not follow any apparent natural

landscape divisions, such as vegetation type borders or small tidal

creeks. However, larger tidal creeks (>20 m wide) did often separate

territories.

Territorial Behavior

Several studies of northern seaside sparrows (Post 1974; Post &

Greenlaw 1975) contain a few quantitative data describing territorial










behavior. Other authors (e.g., Audubon 1831; Nicholson 1946; Norris

1968) anecdotally portrayed territorial and breeding behavior of seaside

sparrows, some in detail and many from an anthropomorphic perspective.

Those reports that best characterize territorial birds and their social

interactions are Norris (1968), Worth (1972), and Werner (1975).

At Cedar Key males began to establish their territorial boundaries

in early March by singing regularly from song perches, usually clumps of

elevated vegetation such as Juncus tussocks located at the edges of

their territories. Overt aggressive encounters were also first observed

at this time and became most numerous in April. Behaviors of such

encounters, in order of frequency of occurrence, were chasing bouts

accompanied by strident "tchi," "zuck," and rapid "tuck" calls;

supplanting (a challenger flew towards a perched bird, and the perched

bird left without dispute); and short-range "facing off" displays,

wherein the participants engaged in wing raises, bobbing, bill

thrusting, and wing and tail flick displays, co-occurring with the

"tuck" and "tchi" calls and "whisper songs."

These Early Season territory-establishment behaviors, as well as

male-female pairing chases, decreased significantly in frequency and in

duration as the breeding season progressed into May. By the end of the

breeding season (June), territorial males seldom disputed intrusions by

neighbors and floaters.

Prior to experiments I conducted in 1983-1986, Post and I believed

that there were no excess males trying to establish territories and

consequentially compress existing territory sizes. I found, however,

that there were such-males, as discussed below in Chapter IV.










Females definitely displayed aggressive behavior towards both

intruding males and other females throughout the season, although I have

few quantitative data on the extent of their involvement in

territoriality. In contrast to males, which were more likely to give

short distance aggressive displays and calls, females were more likely

to supplant and chase intruders. Of the total 3,159 instances of overt

aggressive behavior I analyzed between seaside sparrows in March and

April, 22 percent involved females. Only 5 percent were known to be

female-female encounters. Observations of such encounters were

difficult to make, because females spent more time than males in dense

vegetation. The frequency of female chases of intruders from the

pairs's territory averaged 2.7 chases per hour in late March and early

April. These chases were usually accompanied by the "tchi"

vocalizations and sometimes by a fast rendition of the "whinny"

vocalization (female solicitation call).

Reactions to Other Species of Birds and to Humans

I observed no vocal or other behavioral interactions of seaside

sparrows with resident clapper rails or marsh wrens. Each of these

species seemed oblivious to the sounds emitted by the others. Calls and

songs often overlapped, even when given within close range (<15 m). This

is in contrast to other studies of bird communities, in which singing

characteristics of several species are influenced by each other (e.g.

Popp et al. 1985). Several times I did note that seasides alternated

songs in a definite pattern (countersang) with migrating red-winged

blackbirds (Ageliaus phoeniceus) and bobolinks (Dolichonyx oryzivorus).

Cruising fish crows (notable nest predators of seaside sparrows) almost

always caused seasides to stop singing and sometimes to give "si










twitter" alarm calls (23 observations of low-flying fish crows during

song, 18 instances of song ceasing).

Wintering sharptail sparrows incited aggressive behavior from

seasides, especially when the sharptails began to sing in early May. The

seaside's aggressive behavior was identical to that directed towards

conspecific intruders. Early in the breeding season the mostly silent

sharptails were tolerated and unchallenged. On 17 occasions I heard

distinct countersinging between seasides and sharptails, although their

songs are quite different.

My study population of seaside sparrows seemed oblivious to my

presence, except when I approached to within 5 m or handled them. The

birds were more wary when I was accompanied by field assistants. Other

researchers have made similar observations regarding the "tameness" of

their subject populations of seaside sparrows (Sprunt 1968; Post 1974).

At Cedar Key curious sparrows and wrens approached within 1 m of me when

I was still for 30 min or longer. Indeed, I once awoke from a nap on the

ground to find a sparrow staring at me about 20 cm from my face!

My close approach to nests (<10m), however, did provoke alarm and

sometimes distraction displays from the parents when they were in the

nest vicinity. If the female was on the nest, she usually ran about 3 m

then flew about 5 m farther away. Presumably these reactions are nearly

the same as those given in response to other "predators." Several times

I simulated identical predator-reaction behavior by placing a mounted

fish crow model 2 m from a seaside nest. The typical response by the

parents was high pitched "seeet calls" interspersed with the "tuck"

call, given while the birds rapidly flitted around in the vegetation

within 5 m of the nest. Three times I saw females give apparent










distraction displays by trailing their wings as they ran away from their

nests.

Discussion of Seaside Sparrow Territoriality

Territory types and variation

The seaside sparrow literature indicates that different races, and

populations within races (see Post 1974), may have functionally

different types of territories. These have been described variously as

colonies (Tompkins 1941; Sprunt 1966); areas with separately defended

nesting and feeding areas (Woolfenden 1956, 1968; Worth 1972); grouped

(defended) nesting territories with undefended remote foraging areas

(Post 1974); nest-centered activity spaces ("Type B" of Wilson 1975;

Post 1960); and all purpose breeding territories (mating, nesting, and

feeding; "Type A" of Wilson 1975, Werner and Woolfenden 1983). The

occasional references to seaside sparrows' being "colonial" may be

misleading in that this designation implies the birds had very small

territories, such as those of colonial shorebirds. Although the limited

nesting habitat and the concomitant foraging behavior of some

populations give the appearance of coloniality, seaside sparrow nesting

groups are perhaps better described simply as aggregations.

I have reviewed the literature describing seaside sparrow habits and

have observed populations from Florida to New York. I conclude that

nearly all subspecies and populations exhibit the "all purpose" type of

territoriality. A few populations (e.g. at Post's (1974) Gilgo Beach

study site) exhibited variations of the all purpose type, in that the

birds sometimes foraged out of their territories on undefended areas.

Territories at Cedar Key were of the all purpose type. Occasionally










individuals were seen foraging, unchallenged, on other known

territories.

Territory quality and space use

Post and co-workers (Post 1974, 1981b; Post & Greenlaw 1962; Post et

al. 1983; Greenlaw & Post 1985) comparatively studied the

interrelationships of territory size and quality, predation, food

availability, reproductive success, and mating systems of seaside

sparrows on Long Island, New York, and at Cedar Key, Florida. Their

studies reached several conclusions with which I generally concur: Food

seemed not to be a limiting factor in determining territory size;

"Space-use patterns" (i.e. maintainence of territory size, and foraging

on and off the territories) were more influenced by the numbers of birds

attempting to settle into a habitable area than by food availability.

In other studies Post (1974) and Werner (1975) contended that it is

unlikely that territorial spacing limits the population size of seaside

sparrows. They suggested that as the density of birds increases over

the years the territory sizes simply decrease in order to accommodate

more birds. The population size at Cedar Key remained stable throughout

ny study; thus, I did not have an opportunity to support or refute this

hypothesis under the circumstances of increasing population as described

by these authors. Territorial compression either did not occur at Cedar

Key, or if it did occur then the territories must have become maximally

compressed prior to ny study. I conclude this after considering the

findings of my 1963 and 1984 experiments on territorial birds (Chapter

IV). Because I found that non-territorial males did exist, I contend

that territory boundaries and sizes are not necessarily so flexible as

to accommodate all aspiring breeders, as suggested by Post and Werner.










A few bird studies have established an inverse relationship between

territory size and resources (Zimmerman 1971; Seastedt and MacLean

1979). Greenlaw & Post (1985), however, found that the sizes of the

territories they investigated were not correlated with their composite

index of territory quality (which included nesting, food and

cover/protection factors). Furthermore, territory size was not directly

related to volume of vegetation, area of vegetation, or amount of food

on the territory (Post 1980).

Several recurrent conclusions appear in all seaside sparrow

literature describing territorial and feeding behaviors. My

observations on birds at Cedar Key support most of these: Territory

sizes and probably quality vary considerably within and among

populations. Food is seldom if ever a limiting resource, as

convincingly argued by Post et al. (1983). Animals with small

"nest-centered" territories simply forage, unchallenged, off their

territories. Both migratory and non-migratory males tend to establish

their territories in the same locations year after year. Territorial

shifts within a season rarely occur. Birds in dense populations spend

more time involved in aggressive behavior but neither spend less time

feeding nor suffer lower reproductive success as a result of crowding

(Post 1974). Male sparrows are probably not defending areas for the

food value per se, but are rather advertising and defending territories

in order to increase their chances of mating and keeping mates.

Extension of territory definition and function

Kaufmann (1983) stated that territoriality is one form of social

dominance, dominance being defined as priority of access to critical

resources (e.g. food, mates) that increase the fitness of the dominant










individual. Kaufmann further described territoriality as "relative

dominance." Individual A may be dominant to a subordinate, B, while in

A's territory, but not dominant to B when outside of A's territory.

These interpretations of territoriality are more inclusive than the

restricted working definition I gave at the beginning of this section.

They synthesize that traditional, restricted definition of a territory

as "any defended area" with the broader concept of social dominance.

Kaufmann's characterization of territoriality as one manifestation of

social dominance is quite applicable to seaside sparrows at Cedar Key.

The territories were indeed vigorously defended areas, yet a male off

his territory was invariably subordinate in another bird's territory.

Males together on the few areas of the marsh not occupied by territories

did not evidence dominant-subordinate behavior: apparently shared were

food and the rare female affiliations that occurred outside of

territories. Thus no dominance hierarchy or absolute dominance seemed to

exist.

As Kaufmann (1963) pointed out, arguments about functions of

territoriality have mostly been concerned with whether a territory

serves as an area to enhance social stimulation, or as an area to allow

resource acquisition. Evidence in support of the former hypothesis,

proposed by Darling (1952), is that some birds clump their territories

even when nearby suitable habitat is available. Considering the

synchronized breeding behavior of seaside sparrows and the observation

that populations do indeed clump their territories, one may concur that

social stimulation is a function of territoriality in these birds.

However, I do not believe this to be the case in the birds I have

observed, for the following reasons.










First, I suggest that clumping is a response to many individuals

having the same gestalt perception of preferred habitat, which

researchers have not been able precisely to identify. Since food is

apparently not limiting, I suspect that the preferred habitat for a male

seaside sparrow selecting and setting up a territory is an area of the

marsh that allows maximum singing display advertisement (i.e. moderately

low vegetation with dispersed singing perches such as tussocks of

Juncus). Singing and being able to be heard while singing are vital to

the fitness of male seaside sparrows, as determined by experiments

described in Chapter IV. Thus, what may initially appear to be suitable

unoccupied habitat may in fact be unsatisfactory for establishing a

song-defended territory. Secondly, I do not believe that social

stimulation is a function of territoriality in seaside sparrows, because

their apparently synchronized breeding behavior can almost always be

directly attributed to weather and other environmental conditions, such

as flooding.

For seaside sparrows at Cedar Key, the possession of a territory

does seem unequivocally to allow the owner priority of access to the

resources contained therein, the most important of these probably being

singing perches, a mate, and a relatively undisturbed mating/nesting

area. Thus the territories of seaside sparrows easily fit the

conventional concept of bird territories' being "defended," areas

exclusively occupied by a relatively dominant male. Also applicable is

Kaufmann's broader characterization of a territory as "a fixed portion

of an individual's or group's range in which it has priority of access

to one or more critical resources over others which have priority

elsewhere or at another time. This priority of access must be achieved







39


through social interaction" (Kaufmann 1983, p. 9). Because this

definition includes temporal and relative dominance criteria, this

definition more comprehensively characterizes seaside sparrow

territoriality.
















CHAPTER III
VOCALIZATIONS OF SCOTT'S SEASIDE SPARROWS


Introduction

Seaside sparrows (Ammodramus maritimus) have a vocal repertoire of

distinctive calls and song types. Because these birds are cryptic and

tend to remain low in their densely-vegetated salt marsh habitat, vocal

communication is important in their social behavior. Intergradations and

varying contextual uses of sounds presumably convey different

information to other birds receiving the messages.

Most older seaside sparrow literature is descriptive, and

vocalizations are reported in general and anecdotal behavioral

observations (Kopman 1915; Sprunt 1924; Holt & Sutton 1926; Howell 1932;

Stone 1937; Tomkins 1941; Nicholson 1946; Woolfenden 1956; Norris 1968;

Trost 1963; Worth 1972; Lowery 1974). Relatively recent studies of the

northern seaside sparrow (A. m. maritimus) by Post & Greenlaw (1975)

and of the Cape Sable seaside sparrow (A. m. mirabilis) by Werner &

Woolfenden (1983) include more objective descriptions of calls as well

as songs and associated behaviors. Post & Greenlaw's (1975) detailed

description of the vocal and display repertoire of their Long Island,

New York, population is especially thorough.

In this chapter I describe and discuss the vocalizations of a

Florida population of Scott's seaside sparrow, A. m. peninsuale. I

include more quantitative and conclusive data than in my preliminary

report on Scott's seaside sparrow vocalizations (McDonald 1983c). This










chapter also compares the vocalizations of my study population to those

of northern seaside sparrows described by Post & Greenlaw (1975) and to

those of Cape Sable seaside sparrows described by Werner & Woolfenden

(1983).



General Methods of Data Collection and Analysis

The project history, study site, and subjects were described in

Chapter II.

Coverage

I recorded vocalizations and described the behavior of the study

population throughout the years 1981-1984. My most intensive field work

occurred during the breeding seasons (late February through mid-June)

when I went to the marsh at least 3 days/week. I also visited the marsh

about once every 10 days during the remainder of the year. During the

breeding season I made the majority of my behavioral observations and

recordings when the birds were most active--from just before sunrise

until about four hours after sunrise. The birds' activity level

increased again moderately about an hour before sunset. The few evening

behaviors and vocalizations I recorded seemed not to differ from early

morning observations, thus I only mention their occurrence in this

chapter. Unless otherwise noted, my quantitative descriptions of

vocalizations and behaviors are for observations taken on mild spring

mornings when the temperature ranged from 18-330 C, there was no

precipitation, and the wind ranged from 0-24 km/h.










Sample Size and General Observation Methods

The total number of marked birds (1981-1984) was 213, including

birds manipulated in 1983-1984. In generalizing about the use of

vocalizations, I considered only data for 91 mated and 11 unmated birds

that I had observed for at least 15 h per season. Detailed analyses

were based on fewer males, as described below. I studied each subject

male at least one hour per week throughout the breeding season. On a

typical morning I observed 1-3 focal males for about an hour (an hour's

"time budget" block), then watched another 1-3 males for the next hour,

and so on up until about 0900. I randomly determined the sequence of

these time budget observation blocks. Thus, all birds received

approximately equal coverage that was representative of the morning

hours. Females were difficult to observe; I described their behaviors

and vocalizations as parts of their mates' time budgets.

During the time budget I dictated all observed behaviors and the

birds' locations on cassette tape. I made most recordings (including

all used for sound analyses and sonograms in this section) with a Sony

TC 150 cassette tape recorder (Mineroff-modified), using a Bell and

Howell "Shotgun" unidirectional electret condenser microphone with

windscreen. I measured the amplitude (in dB) of a singing male 7 m from

me with a Bruel & Kjaer Sound Level Meter (Type 2219) on 5 Apr 1985.

I also used field data forms to record contextual information,

banding records, nest descriptions, territorial boundaries, and other

biological information. Territory maps for the entire population were

drawn in the field at least bi-weekly throughout the breeding seasons.










General Analysis of Notes and Recordings

I transcribed, tabulated, and summarized the behavioral data. I

determined characteristics of tape recorded sounds (e.g. frequency

ranges, length of song) with a Uniscan II FFT Real Time Sonogram

Spectral Display (Model 4600), and prepared sonograms (Fig. III-i

through Fig. III-10) with a Kay Elemetric 7029A Sono-graph using the

wide-band filter (300 Hz) and either the 80-8000 Hz or the 1600-16,000

Hz scale. The specific vocalizations and behaviors I analyzed are

listed in Table III-1.

Detailed quantitative descriptions of vocalizations and other

behaviors were determined from an analysis of 103 time budget hours of

30 mated and territorial best-studied males. I chose time budgets for

analysis based on comparability of day of year (Apr-May), time of day

(sunrise-0900), and the typical mild weather conditions described above.

I used non-parametric statistics (Siegel 1956; Conover 1980) for the

analyses.

My specific methods of investigating flight songs ("complex flight

vocalizations" of Post & Greenlaw 1975) and countersinging are discussed

in separate sections below.










Table III-1. Vocalizations and behaviors measured during time budget
observations (in min and sec duration, and frequency)


Singinga,b
Primary song
Whispering song
Matched countersinging
Not matched countersinging
Flight song

Other Vocalizationsa ,b
Tuck
Tsip
Si Twitter
Seeep
Tchi
Tchi flight
Whinny
Zuck and other calls

Position Changesab
When not singing
Singing, song type change
Singing, no song type change
Singing, stop singing


Observations Relating to Females


and Younga'b


Female present
Female solicitation calls, other calls
Copulations
Females building nests
Other behaviors related to females and young

Other Behaviora,b
Feeding, resting, and preening
Off territory: feeding; invading nearby territory

Reactions to Intrudersa,b
Frequency, duration, and location of intruder
Flight chases
Vocalizations: Displays:
Solo primary song Sham-preen
Countersong Grass-pick
Whispering song Bob and bill jab
Calls (as above) Contact

a Contextual information also noted: bird's identity, location, mated
status; presence of conspecifics, date, weather, and location of
observer.
bTerminology follows Post & Greenlaw 1975.












Results and Discussion of Calls and Song

Descriptions and Use of Vocalizations

Scott's seaside sparrows make 14 distinct vocalizations: a primary

song, three modifications of the primary song, and 10 calls. The

probable functions of their songs and calls are summarized in Table

III-2. I distinguish "songs" from "calls" as implicitly defined by most

ornithologists, and as specifically stated in Pettingill's working

definition: "Song is a vocal display in which one or more sounds are

consistently repeated in a specific pattern. It is produced mainly by

males, usually during the breeding season. All other bird vocalizations

are collectively termed call notes or, simply, calls" (Pettingill 1970,

p. 319). I use Post & Greenlaw's (1975) vocalization terminology

throughout, except for "whispering primary song," which is from Werner &

Woolfenden (1983).










Table 111-2. Vocalizations of Scott's seaside sparrows


Vocalization
a
Name-
Primary song


Whispering
song

Complex flight
vocalization

Subsong
(young birds)

Tuck


Tsip call and
Si twitter

Seeep note



Tchi
vocalization


Whinny
vocalization

Zuck call


Scree call

Begging and
Chup calls


Sex and
Context-
Male;
1, 2, 4

Male;


Male;
1, 2, 5

Male;
1, 4

Male and Female;
1-5


Male and Female;
1-3, 5

Male and Female;
1, 2, 5


Male and Female;
1-3, 5


Female;
1, 2, 4


Male and Female;
1, 5

Male and Female; 3

(given by young
only)


Probable Function(s)

Territory defense and
mate attraction

Territory defense
during intrusion

Territory defense and
mate attraction

Practice song


General purpose;
moderate aggression;
chase; nest defense

Heightened aggression;
attack; nest defense

Proclaim location of
female(?); fear(?);
Flocking (fall & winter)

Moderate aggression;
chase; female: nest area
distraction, proclaim sex


Attract males for
copulation


Heightened aggression;
chase; drive off young

Extreme distress call

Begging for food


aTerminology follows Post & Greenlaw (1975). This table is modified
from Post & Greenlaw's (1975) Table 3, which summarized "vocal
displays" of northern seaside sparrows.
bcontexts in which the vocalization were elicited: 1-in presence of
intruder or neighbor bird; 2-in presence of mate; 3-in presence of
predator, or human disturbance; 4-also given when bird apparently alone;
5-given in flight.











Calls of Scott's seaside sparrows

In this section I give sonograms, descriptions, and suggested

functions of 10 calls, presented in approximate order of their frequency

of occurrence during the breeding season.

Tuck call

The "tuck" (Fig. III-1A) was the most common of the calls. It was

given by males and females throughout the year. The short tuck covers a

wide frequency range and is probably the same call Werner & Woolfenden

(1983) labeled as the "chip" call for Cape Sable seaside sparrows. The

tuck appeared to be an all-purpose vocalization, but seemed to function

mostly as a general alarm and moderately intense aggressive call. It

was invariably given during short-distance aggressive interactions and

usually accompanied by wing and tail flicks, and by the "tsip" calls

(shown specifically in Fig. III-1A).

Males gave tuck calls at an average rate of 0.3 min/h when there was

no apparent disturbance on their territories. During intrusions,

however, the tuck rate increased to 13.5 min tucking/h intruder present.

This call was also given alone (or together with "tsips") by both

parents when a predator or human approached a nest within 5 m. The tuck

call was the only one I heard regularly during the non-breeding season.

I also heard fledglings and juvenile birds give this call.

Tsip and si twitter

Both males and females also gave the higher-pitched, short "tsip"

call (Fig. III-1B). When birds were highly agitated the "tsip" was

rapidly repeated, thus intergrading into the "si twitter" call. The

"tsip" was often interspersed with "tuck" calls, as mentioned above, and










was accompanied by wing and tail flicks. During bouts of calling, which

lasted 0.25 to 17.3 min, birds gave "tucks," "tsips," and combined

"tuck-tsips" at a rapid and usually regular rate of 30-145 calls/min.

As with the "tuck" call, "tsips" and "si twitters" generally signaled

alarm and aggression, but more often indicated a higher level of alarm.

My closest approach to nests (<2 m) and my placing of a stuffed fish

crow near nests nearly always elicited "si twitters." I never heard

"tsips" or "si twitters" from undisturbed birds. During intrusions the

average combined "tsip-si twitter" rate was 4.5 min tsip-si twitters/h

intruder present. I only rarely heard the "tsip" call during the

non-breeding season, and I never heard fledglings or juveniles give

either of these calls.

Seeep note

During the breeding season I occasionally heard females give a soft,

high-pitched "seeep" call Fig. III-1C). Most of the "seeeps" occurred

during bouts of copulation. Sometimes a female gave this call as a

nearby male began to sing relatively softly (Fig. III-2A). Post &

Greenlaw (1975) suggest that the "seeep" call conveys a weak fear

message. This call, or a very similar one, was the second most common

vocalization I heard outside of the breeding season. Males and females

of both Scott's seaside sparrows and wintering sharptail sparrows at

Cedar Key gave "seeeps," especially in the late fall and early winter. I

agree with Post & Greenlaw (1975), and with Werner & Woolfenden (1983),

that this call probably functions as a social and flocking vocalization

outside of the breeding season.










Tchi vocalization

The loud and relatively short "tchi" call (Fig. III-2B) was given by

both sexes and was most often heard during chases. About half of the

total thisi" I heard were given during or immediately following chases.

Usually the thisi" were rapidly repeated, and frequently they

intergraded with a slower, slurred "tyu." The "tyu" itself often slurred

into a "whinny"-like vocalization (described below). The "tchi" call

was probably the same as the "squeaz" call described by Werner &

Woolfenden (1983), and the same as the "jee-jee-jee-jee-jee-jeeeu-jeeeu"

call described by Norris (1968).

The primary function of this call seemed to be signalling general

aggression during chases. Frequently, however, I heard females give

rapid thisi" in flight ("tchi flight") as they left a nest they were

building or incubating, even though no threatening bird seemed to be in

the vicinity. These nest-departure thisi" were not given adjacent to

the nest, but rather at about 10-15 m from the nest. During a 1 h

observation of nest building in early May 1983, for example, I saw a

female depart and come into her nest 18 times. Fifteen of her

departures were accompanied by thisis" but only one arrival was

accompanied by this call. Jon Greenlaw (pers. comm.) reports that female

northern seaside sparrows behave in a similar manner. I suggest,

therefore, that the "tchi" also functioned as a distraction call by

drawing a potential predator's attention away from the nest as a female

departs. Jon Greenlaw (pers. comm.) also thinks that thisi" in the

nest vicinity function to let the resident male know that this departing

and arriving bird is a female who belongs, rather than an invading male.










Other than the females giving the "tchi" as described above, I

seldom heard this call when no intruders were present (0.11 male

tchis/non-intrusion hour). It was difficult to quantify the "tchi" rate

during intrusions. On the average, however, a territory owner spent

2.62 min chasing/h intruder present. I estimate that at least half of

these chases were accompanied by rapidly repeated thisis" most of these

calls given by the owner.

Whinny vocalization

I heard only females give the "whinny," with one unusual exception

described below. This whirling, quavering call varies in rate from 0.3

to 3/sec (Fig. 111-3). The whinny was the female's solicitation call;

it functioned to attract a male. Females gave this call more often when

a male was relatively close to her (within about 7 m), and especially if

the male was singing. Males were immediately attracted to the "whinny"

vocalization, and copulation usually followed. Even though females gave

the "whinny" from on or near the ground, males seemed to have had no

problem finding the vocalizing females. It is likely that some auditory

characteristics) of this vocalization made it easy to locate.

Females gave this call most often prior to, and during nest

building. Because females usually initiated up to 5 clutches per

breeding season, the overall intensity of "whinnies" heard for the

population remained the same from late March through May. The average

whinny rate heard on all territories during these months was 2.02 min

whinnies/h.

Post & Greenlaw (1975) describe the postures associated with the

"whinny" vocalization and copulation. Werner & Woolfenden (1983) do not

describe a female solicitation vocalization.











I only once heard a male give a distinct "whinny" (as opposed to the

"whinny"-like "tyu," described above). On 6 May 1984 a male invading an

experimentally muted bird's territory repeatedly gave whinnies while he

intruded.

Zuck call

The loud, raspy "zuck" (Fig. 111-4) was an aggressive call given

during intense fights. Most of the zucks I heard were given by males,

but sometimes females and juveniles gave this call. It may have been the

same as the "Shu-shu...shu" call of Cape Sable seaside sparrows that

Werner & Woolfenden (1983) mention but do not describe. In addition to

its functioning as a general, high intensity aggressive call, "zucks"

were the vocalizations most often given by fathers when they drove their

older, almost independent fledglings off their territories (about 2-3

weeks post-fledging). Other than these father-fledgling encounters, I

never heard this call given during non-intrusion circumstances. During

intrusions both territory owners and intruders gave "zucks" (often mixed

with thisis) at the rate of 0.7 min zuck/h intrusion.

Other calls

The "Scree" (Fig. 111-5) was a harsh distress call I heard only

(with a few rare exceptions) from a few birds trapped in mist nets and

being handled. Both sexes of adults and juveniles gave this call.

The monotonous and insistent "Begging Calls" (Fig. 111-6), given by

older nestlings and fledglings, were heard most often towards the end of

the breeding season. Nestlings gave "Peep" (Werner & Woolfenden 1983)

and "Chup" (Post & Greenlaw 1975) calls.

Post & Greenlaw (1975) describe one further call I have not

mentioned--the "Chew" call. To my knowledge, I never heard this call at







52


Cedar Key. Jon Greenlaw (pers. comm.) proposes that the "Chew" call is

probably a modified "tchi-whinny" vocalization.

















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Primary song

Audiospectrogram. The seaside sparrow primary song (Fig. 111-7) is

relatively simple. The introductory portion of rapid clicks (centering

around 6.5 kHz) is immediately followed by a buzzy trill (centered

around 3.8 kHz). These frequency ranges and the song duration of about

1.0 second were characteristic for the entire population.

General description of singing behavior. During my study, only

males sang. Although Post & Greenlaw (1975) describe "female songlike

vocalization" that resembles male song, I never heard a vocalization of

this type at Cedar Key. Aales sang to delineate territories and to

attract females. Experimental evidence for these functions of song is

given in Chapter IV.

Males usually sang from elevated perches, such as tussocks of

Juncus. Most birds had 3-7 favorite singing perches within their

territories from which they gave about 35% of their songs. From

1979-1984 only two males sang from grid marker stakes, although Post &

Greenlaw (pers. comimi.) found that birds in their dense study population

often sang from grid markers.

The singing pattern of seaside sparrows is similar to that of many

song birds (Table 111-3). Birds sang in "discontinuous" patterns of song

"bouts" (songs repeated continuously without a pause), of "eventual

variety" (song type change after three or more repetitions of the same

song type) (Hartshorne 1956; 1973). An average bout throughout the

season consisted of 19.2 songs and lasted 1-5 min (mean = 1.62). Highly

variable periods of silence (mean = 7.9 min) separated song bouts. Males

changed perches during 17% of these between-bout silences, before

resuming singing. Song rate within a bout ranged from 6-9 songs/min










Table 111-3. Characteristics of solo primary singing and countersinging
of 30 mated male Scott's seaside sparrows during April and May



Primary
Song (Solo) Countersong b
Characteristics Total Total Matched Not Matched


N (bouts) 391 223 143 80

Mean bouts/h obs. 3.80 2.17 1.39 0.73

Total min sing 635 631 438 192

Mean min sing/h obs. 6.16 6.13 4.26 1.86

Mean min song/bout 1.62 2.83 3.07 2.40

Total bouts edgec 198 123 30 43

Total bouts center 117 41 26 15

Total min edge 315 369 275 94

Total min center 193 110 66 44

Mean song type <0.01 0.02 0.02 <0.01
switches/bout

Mean song type 0.32 0.33 0.47 0.29
switches/h sing

Mean perch 0.97 0.33 0.31 0.35
changes/h sing

Mean perch changes/ 0.16 0.02 0.02 0.01
bout

Mean perch changes/ <0.01 <0.01 <0.01 <0.01
bout with song switch

Mean perch changes/ 0.03 0.02 0.02 0.01
bout without switch

Mean perch changes/ 0.13 0.05 0.01 0.02
bout, song cessation







75



Table 111-3, continued.

Characteristics of solo primary singing and countersinging determined
from analyses of 103 h of time budget observations, when no intruders
were present on focal birds' territories. Other conditions during time
budget observations are described in the text.
bRate values calculated for Matched and Not Matched columns based on
number of bouts and minutes of Matched and Not Matched singing,
respectively. Thus the sums of rates of Matched and Not Matched values
do not add up to the Total column for Countersong.
c
Edge defined as the outer-most 10 m of the bird's territory.

dCenter defined as the area within a 25 m radius of the estimated center
of the bird's territory.










(mean = 7.7), close to the 6.6 song rate Woolfenden (1956) reported for

New Jersey birds, and slightly lower than the 10.6 song rate reported by

Post & Greenlaw (1975).

Individual males had a repertoire of two to four similar song types

(mean = 2.41). When both solo singing and countersinging, birds seldom

switched song types within or even between song bouts. The mean rate of

song type switches during a bout was about 0.01/bout. Thus their

singing was extremely "monotonous," sensu Hartshorne (1956; 1973),

because their singing pattern was both continuous and of low

"versatility" (infrequent song type changes).

Most males shared their song types with nearby territorial birds. A

few of the birds had one highly distinctive song type within their

repertoire that enabled me to recognize individuals aurally from as far

away as 150 m. I did not detect any tendency for males to have a

preferred song type from within their small song repertoire.

Seaside sparrows at Cedar Key seldom began a new song type after

moving to a new perch while singing (Table 111-3). Of a total 67

incidents of perch changes during singing, there was only one concurrent

song type change. This constrasts with Krebs's (1977a, 1978) "Beau Geste

hypothesis" that territorial birds switch song types when changing

perches, thus possibly giving potential intruders the impression that

territories are saturated.

Influence of abiotic factors on singing behavior. Singing activity

varied throughout the year. It was most intense relatively early in the

breeding season (late March through mid-April), especially before and

just after birds were mated. The average time singing of 29 males

measured 1-15 Apr 1983 was 19.4 min singing/h. In the third week of May










their song rate decreased to 12.1 min singing/h, a significant

difference (two-tailed Wilcoxon matched-pairs signed-ranks test, T=2,

P<0.01).

Weather modified the intensity of singing, on both a daily as well

as a seasonal basis. Very early in the spring (February through mid

March) birds sang more as the day warmed slightly, up to about 200 C.

During the middle and especially towards the end of the breeding season,

birds sang less as the day warmed. Virtually all singing stopped at

temperatures above 320 C, regardless of the time of day. From the middle

of the breeding season till the end, birds sang more on cloudy, cool

mornings. Light rain also enhanced singing activity at this time of the

year, and even heavy rain and thunder and lightning dampened singing

activity only slightly. Brisk winds (>25 km/h), however, greatly

reduced singing activity, especially early in the season on cool days.

The intensity of singing activity also varied throughout the day.

Peak song activity was early in the morning, from sunrise to about 3

hours after sunrise. The earliest I heard singing was 20 min before

sunrise. Birds also sang in late afternoon until about one-half hour

after sunset. Compared to seaside sparrows on Long Island, New York,

that I observed in June 1982, birds at Cedar Key sang less in the

evenings. The first morning and last evening songs were similar to

songs given during peak morning activity, except the song rate

(song/min) within the bout was lower very early and late in the day.

Influence of other birds on singing behavior. Unmated males sang

significantly more bouts than mated males, and thus their total time

singing (21.4 min/h) was greater than that of mated males (12.3 min/h),

as measured in May (two-tailed Mann-Whitney U-test, N=30 and 11,











P<0.01). Singing rate also differed significantly according to whether

an intruding male seaside sparrow was present. After territories were

well established (by mid-April), intrusions were rare (mean = 0.7 min

intrusion/hour). When an intrusion did occur an owner's first reaction

was increased singing, and this was often successful in repelling the

intruder. If the intruder was not driven off by normal primary song,

territory owners switched to short-distance and more aggressive

vocalizations and behaviors--whispering primary songs, tuck and si

twitter calls, chases, quivering wing raises, and (rarely) contact

fights.

The "whispering primary song" (Werner & Woolfenden 1983) was a

slowly delivered (mean=3.5 song/min), low amplitude, and slightly lower

pitched modified primary song. It was usually given by a male perched

near the ground and confronting an intruder at 1-5 m. The whispering

primary song was delivered with an almost closed beak, in contrast to

the normal primary song where the bird threw back his head and opened

his beak wide as he sang. I do not have data describing reactions of

males that heard these whispering songs. Because I only heard it during

agonistic encounters, this vocalization may have functioned to transmit

a message of threat and likelihood of attack. Jarvi et al. (1980)

described a similar use of modified primary song in the willow warbler

(Phylloscopus trochilus) that transmitted a message that the singer was

likely to attack his opponent.

Because short-distance encounters were more often accompanied by

calls and displays, the combined normal and whispering primary song rate

during intrusions (2.4 min song/h intrusion) was much lower than the

song rate when no intruder was present (12.3 min song/h non-intrusion).










Calls of most other marsh birds, including the raucous clapper

rails, seemingly had no effect on the seaside sparrows' vocalizations or

other behaviors. Seaside sparrows did respond antagonistically toward

vocalizing sharp-tailed sparrows (Ammodramus c. caudacuta) when these

wintering migratory birds began singing prior to their departure the

first week in May.

Subsong

Young males sang rudimentary subsong late in July and in August

(Fig. 111-8). These songs consisted of garbled warbles and parts

(usually the terminal trill) of the adult primary song. Subsong was not

as loud as the primary song and was sung only sporadically instead of in

bouts. These first song attempts improved and came to resemble the

adult's primary song by late fall, when virtually all singing activity

stopped. Both yearling and adult males began to sing again in late

February, and songs of the first year birds could still be

differentiated from those of older birds. By mid-March, however, songs

given by first-year and older birds could no longer be distinguished.

Countersinging and Repertoire Use

Introduction and comments

Countersinging occurs when two, three, and sometimes four male birds

alternate their songs in a regular pattern. Countersinging is described

as "matched" when the same song type or types are sung by the

participating birds. The behavioral and evolutionary significance of

song repertoire sharing in general, and of song matching during

countersinging in particular, has been the subject of recent stimulating

studies (Krebs & Kroodsma 1980; McGregor et al. 1981; Payne 1982; Kramer

et al. 1985; Searcy et al. 1985).










Many relatively simple explanations for song matching exist:

Matching indicates high-intensity interactions (Lemon 1968b). Birds

match in order to monitor the positions of their neighbors (Lemon

1968a). Relative dominance between countersinging birds influences the

degree of matching (Kroodsma 1979). Time intervals between songs of

countersinging birds indicate which of the participants is dominant

(Smith & Norman 1979). Matching functions as a vocal threat that

regulates distance between birds (Todt 1981). Matching is a graded

signal used in territorial encounters (Krebs et al. 1981). Finally,

matching indicates readiness to interact aggressively (Horn & Falls

1986).

Further interpretations of song sharing that deal more generally

with repertoires and repertoire sharing (which may or may not involve

matched countersinging) are: Larger song repertoires make recognition

of neighbors more difficult (Falls & d'Agincourt 1981; Searcy et al.

1981). Larger repertoires are more attractive and stimulating to

females (Howard 1974; Searcy et al. 1982). Larger repertoires allow

resident birds to fool potential intruders through increasing the

perceived density of singing birds (Krebs 1976), and, young indigo

buntings (Passerina cyanea) mimic the repertoires of older territorial

males and thus deceive other males through mistaken identity (Payne

1982). Searcy et al. (1985) found no correlation between song repertoire

size and male "quality" in song sparrows (Melospiza melodia).

While these may or may not be adequate explanations for song sharing

in birds, some recent experiments on song sharing have become

increasingly sophisticated. These studies have incorporated more

objective methods of determining song similarity, the possible effect of










sound degradation from sender to receiver influencing behavior, the

birds' natural use of their repertoire, and their familiarity with

neighboring males (Falls et al. 1982; Schroeder & Wiley 1983b; Whitney &

Miller 1983).

Almost all investigations of song matching and repertoire use have

involved playback experiments and measures of response strength to the

tape recorded songs. Ideally, field studies to determine the occurrence

and significance of song sharing (without using controlled playback

experiments) would be on birds with only one or two songs in their

repertoires. Usually, though, this is not the case. Therefore a major

design consideration in natural observational investigations is first to

make comprehensive studies of normal singing behavior of undisturbed

birds. That is, the song repertoires (and the possible differential use

of songs from within the repertoires) of all subjects must be thoroughly

analyzed, and the probabilities that each bird will sing a given song in

different circumstances determined. Simply describing the composition of

the bird's repertoire is not adequate.

Studies of the birds' natural use of song types are complicated by

additional considerations. The observer's method of determining degree

of song similarity may greatly influence the results. Also, some birds

are known to use different song types according to: location within

their territory (Lemon 1968b; Lein 1978; Schroeder & Wiley 1983a),

whether a male or female is present (Smith et al. 1978; Schroeder &

Wiley 1983b), distance from rival conspecifics (Simpson 1985);

familiarity with the neighboring male (Wunderle 1973; Falls et al.

1982); similarity of rival male's song to self song (McArthur 1986),

rate of song type switching (Simpson 1985), acoustic degradation over











distance (Morton 1982; McGregor et al. 1983); overall aggressive

motivation (Lein 1978; Schroeder & Wiley 1983a); and stage in breeding

(Falls & Brooks 1975; Petronovitch et al. 1976). Furthermore, three

recent studies have shown that the intensities of agonistic interactions

were not correlated with the choice of song types per se, but rather

with the rate of song type switching alone (Kramer et al. 1985; Simpson

1985) or together with the degree of matching (Horn & Falls 1986).

Thus, what may appear to be unambiguous results from studies of how

birds use their repertoires, including song matching during

countersinging, should be carefully evaluated. Some recent studies

have, however, more scrupulously investigated countersinging and song

type use in general based on detailed analyses of repertoire composition

and contextual use (McGregor & Krebs 1982; Schroeder & Wiley 1983a,

1983b; Simpson 1984, 1985.; Lemon et al. 1985).

The purpose of these introductory remarks is several-fold. First, a

field study seeking to describe and interpret the function of repertoire

sharing and countersinging is likely to be more complicated than is

intuitively obvious. The design must consider many variables that may

be difficult, if not impossible to control. Secondly, I introduce this

section on the countersinging of Scott's seaside sparrows with these

remarks in order that the reader may realize why I present only

descriptive summaries rather than the testing of the significance of

repertoire sharing and matched countersinging.

Methods of investigating repertoires

When birds countersang during time budget observations, I noted

whether they matched or not, in addition to taking my standard singing

behavior measurements (bird's identity, presence or absence of










intruders, time singing, perch changes while singing, and incidence of

song type switching). As described in the "General Methods," I

tabulated in detail 103 time budgets (selected for comparability of

date, weather, absence of intruder, etc.) for 30 mated males observed

Apr-May 1981-1984.

Results and discussion of repertoire use

I measured parameters of solo primary and countersinging activity of

Scott's seaside sparrows (Table 111-3). The mean total singing activity

(solo singing and countersinging) for males was 12.29 min song/h.

Two to four males often participated in bouts of countersinging, the

alternation of songs separated by 3-8 sec (Fig. 111-9). The pattern of

song alternation was usually regular, but in 3% of the countersingng

bouts the alternating songs drifted out of phase and began to overlap.

Countersinging comprised about half of the total singing time.

Approximately two-thirds of the total countersinging time was matched

countersong (Table 111-3).

The mean song repertoire size of the 30 males was 2.41

songs/bird/season. I did not measure the proportional use of song types

within repertoires, nor did I measure the degree of repertoire sharing

within the population.

Some conclusions are apparent from the data presented in Table

111-3, even without statistical testing. First, apparently neither solo

singing nor countersinging was preferred in the several contexts

analyzed. That is, countersinging did not seem to be used

proportionately more often than solo singing at territory edge, nor did

perch and song type switches seem to be correlated more or less strongly

with countersinging. The same lack of differential patterns according










to context seemed to exist when comparing matched to non-matched

countersinging. A possible exception is that birds may have sung more

minutes of matched song than non-matched song at territory edges.

Of course more comprehensively analyzed data are needed before

statistically valid statements regarding repertoires and countersinging

in seaside sparrows can be made. I do, however, conclude the following

at this time. First, countersinging is a form of vocal "duelling" that

indicates a slightly elevated aggressive or aroused state. That is,

countersinging is a graded signal in seaside sparrows, but probably a

less strongly graded signal than in most birds. Second, song matching

while countersinging and repertoire sharing in general in these birds

are probably chance events, analogous to the "epiphenomena" of song

pattern variety suggested by Wiens (1982) for sage sparrows (Amphispiza

belli). Songs of seaside sparrows may be observed to match simply as a

consequence of their small repertoires of simple and similar songs,

their low population turnover rates, and their sedentary habits.

Flight Songs: Description and Comparison to Perch Songs

Description

An early Florida naturalist, Donald J. Nicholson aptly

characterized seaside sparrow singing: "Towards the end of March the

marshes are fairly buzzing with the purring, wheezing songs...He tries

one perch and seeks another fifty or seventy-five yards away flying low

over the rank growth. Every so often he fairly 'explodes' with passion

leaving his concealment to rise on fluttering wings sixty or seventy

feet above the marsh uttering his erratic little song as he goes up and

down dropping out of sight in the salicornia" (Nicholson 1946, p. 41).











The flight song (Fig. III-10), accompanying the flight song display,

is a combination of preliminary calls followed by the primary song. This

vocalization and display of about 3-4 sec is sporadically given by males

throughout the breeding season. It begins with introductory

high-pitched "si" calls, followed by lower-pitched "tuck" calls, and

ends with one or two condensed versions of the primary song. The buzzy

trill of the primary song portion is about 0.4 sec shorter than the

trill of the normal primary song. The introductory calls vary in

duration and type, but are always given on the ground and during the

bird's ascent to about 10-15 m. The primary song is uttered as the bird

descends. Woolfenden (1956), Trost (1968), Post & Greenlaw (1975), and

Werner & Woolfenden (1983) also describe singing and flight songs of

seaside sparrows.

Methods of investigating flight song activity

My observations of Scott's seaside sparrows during the breeding

seasons of 1981-1982 suggested that overall song activity seemed to be

affected by whether the birds were mated, and by time of day, time of

year, and weather. In most Passerines these factors do influence the

intensity of primary song singing from a perch (hereafter designated in

this section as "perch singing"). I measured and compared perch song

and flight song activities of my study population during the early

breeding season of 1982. Then I tested whether the above factors

differentially affected flight song activity (as compared to perch

singing) by comparing the relative frequencies of flight songs to perch

singing under specified conditions described below.

I sampled the overall singing activity of 28 males during 31 field

days from 12 Feb-26 Apr 1983. Throughout the day I monitored flight










song and perch song activity within one hour time blocks from pre-dawn

through mid-afternoon. The time blocks were designated in hours

relative to sunrise: the first hour block of a day began 15 min before

sunrise, the second hour block began 45 min after sunrise, and so on. I

randomly chose and timed the perch singing of a different male during

each hour block. Simultaneously, I counted all flight songs heard within

100 m during the hour. As I counted and timed songs during each hour

block, I also noted wind velocity, temperature, the singing bird's

location, and identity and mated status (if known).

In summarizing my data, I defined an hour's "flight song activity"

as the average number of flight songs heard within the 100 m radius

during the hour. I defined "perch song activity" as the average number

of minutes the randomly chosen birds sang during the hour within the

same 100 m. Then, for every level of increment of the variables being

investigated (e.g. for temperature category 5-9 C), I tabulated flight

song activity (FS), perch song activity (PS), and a calculated FS/PS

ratio. A statistical analysis using multiple regression would have been

the ideal method of exploring these data. Yet because some data were

ordinal rather than interval and normality was not assumed,

non-parametric statistical analyses were required. In order to validly

consider the effect of only one variable at a time, I chose subsets of

data, as described below for each analysis. I used Spearman rank

correlation (Siegel 1956) to determine if PS, FS, and FS/PS ratios were

correlated with day of year, time of day, temperature, and wind

velocity. I tested significance of the correlation coefficient at the

two-tailed P<0.05 level. I also compared FS and PS activities of mated
2
and unmated birds with a two-tailed X one-sample test (Siegel 1956).










Results of singing activity analysis

Males sang perch songs at an overall rate of 17.1 (SE=5.9) min

song/h. Flight song rate varied considerably among males. The mean rate

was 0.15 flight songs/male/h. The rates of perch songs, flight songs,

and FS/PS ratios did, however, vary significantly as detailed below.

Four variables correlated significantly with both perch singing and

FS/PS ratios: day of year, time of day, temperature, and wind velocity.

Mated and unmated birds differed significantly in the number of flight

songs given.

Day of year. I analyzed the following subset of data to determine

the correlation of singing activity with day of year: 88 h of

measurements for unmated birds taken on 19 days when the temperature was

15-24o C and the wind was <24km/h. I found that perch song activity

increased significantly (r=0.72), and FS/PS ratios (r=-0.81) decreased

significantly as the breeding season progressed, up until the last week

of April. Flight song activity considered alone, however, did not

correlate significantly with day of year (r=-0.01).

Time of day. I determined the effect of time of day by considering

the same subset of observations: 88 hours of measurements for unmated

birds noted when the temperature was 15-24 C and the wind was <24km/h.

I found perch song rate was greatest just after sunrise and declined

significantly (r=-0.95) as the day progressed (excluding evening

singing). Flight song activity remained about the same all day,

although the FS/PS ratio increased significantly (r=0.33) through the

day (Fig. III-ll).

Wind. I analyzed the following subset of data to determine the

effect of wind: 79 morning hours (hour blocks 1-5) of measurements for










unmated birds noted when temperatures were 15-24 C. I found that brisk

winds had a definite dampening effect on perch song activity (r=-0.97)

but no significant effect on flight song activity. The FS/PS ratio

increased significantly (r=0.88) as wind velocity increased (Fig.

111-12).

Temperature. To determine the influence of temperature, I

considered 77 hours of observations made on unmated birds, during hour

blocks 1-4, and when the wind was <24km/h. I found that cooler

temperatures significantly (r=0.88) decreased perch song activity but

had no significant effect on flight song activity. The FS/PS ratio did

significantly decrease (r=-0.83) as temperature rose (Fig. 111-13). In

other words, as with high winds, birds gave proportionally more flight

songs in cooler weather.

Mated status. I considered the singing activity of 23 males before

and after they were mated. The time elapsed between measurements was

8-19 days. I observed birds for 73 h during hour blocks 1-4, when

temperatures were 15-24o C and the wind was <24km/h. Males sang less

(14.9 min/h) after they were mated than before mated (19.7 min/h), but

this decrease in singing may have been at least partially due to the

seasonal decline in singing activity described above, or vice versa.

From a sample of 122 flight songs, 74 were given by birds of known

mated status. Unmated birds sang 84% of these 74 flight songs (Fig.

111-14). This difference was highly significant (two-tailed X2

one-sample test, X2=33.8, df=1, P<0.001).

Discussion of flight songs

Flight songs are characteristic of birds that live in open

grasslands or tundra. Many emberizine sparrows, including the







89


congeneric seaside, sharptail, Baird's (A. bairdii), and Le Conte's

sparrows (A. leconteii), have well-developed flight songs.

Why do seaside sparrows give flight songs? Although the flight song

is a highly conspicuous vocalization, obviously its energetic cost is

greater than that of perch singing. Post & Greenlaw (1975) report that

in their migratory northern seaside sparrows, flight songs are much

more common soon after females arrive on their male's territories. This,

as well as my findings that unmated Scott's seaside sparrows gave more

flight songs than mated birds, suggests that flight songs may be used in

mate attraction. All seaside sparrows, however, continue to give these

vocalizations throughout the breeding season.

A major portion of the flight song vocalization is the uttering of

one or two modified primary songs. Elsewhere (Chapter IV) I have shown

experimentally that the primary song is essential for both mate

attraction/retention and territory establishment/retention. Thus, it is

reasonable to assume that flight songs can effect the same critical

functions. I have presented evidence that birds give relatively more

flight songs (and sometimes they give only flight songs) during

inclement weather and when unmated. I therefore suggest that even

though they may be energetically costly, flight songs so effectively

magnify the message of the primary song that they are worth more to the

male, especially under otherwise adverse singing conditions.