Small mammal communities in an eastern Brazilian park

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Title:
Small mammal communities in an eastern Brazilian park
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ix, 200 leaves : ill. ; 28 cm.
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Stallings, Jody R., 1954-
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Subjects / Keywords:
Mammals -- Brazil -- Rio Doce State Forestry Park   ( lcsh )
Mammals -- Habitat   ( lcsh )
Habitat (Ecology) -- Brazil -- Rio Doce State Forestry Park   ( lcsh )
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bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1988.
Bibliography:
Includes bibliographical references (leaves 187-199).
Statement of Responsibility:
by Jody R. Stallings.
General Note:
Typescript.
General Note:
Vita.

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University of Florida
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All applicable rights reserved by the source institution and holding location.
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oclc - 20442537
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Full Text












SMALL MAMMAL COMMUNITIES
IN AN EASTERN BRAZILIAN PARK

















By

JODY R. STALLINGS


A THESIS 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


1988
















ACKNOWLEDGEMENTS


This project could not have been carried out without the help

of numerous people. Foremost, I thank John G. Robinson for

suggesting the research project in the Rio Doce State Forestry

Park. His perception and patience aided in all aspects of the

project and his visit to the project site in May, 1986, was a great

boost to my morale. I would also like to thank the other members

of my committee for their suggestions during the planning stage and

for helping me to interpret the data. I thank Drs. John F.

Eisenberg, Melvin E. Sunquist, Wayne R. Marion, and Nigel J. H.

Smith. John Eisenberg was a constant source of support through the

analysis and writing stages. His continued interest in the results

and concern for my welfare helped to carry me through difficult

periods. Kent H. Redford provided obscure and relevant

publications. He also visited the field site at the beginning of

the project and encouraged me to sample the eucalypt forests.

Funding for this project was provided from the Program for

Studies in Tropical Conservation at the University of Florida,

World Wildlife Fund-US, The Organization of American States, and

the Instituto Estadual de Florestas (IEF). I thank John Robinson,

Kent Redford, Russell Mittermeier, John Eisenberg, Jose Carlos










Carvalho, and Cello Valle for helping me to obtain the funds

necessary to carry out the project.

I would like to thank Jose Carlos Carvalho, president of IEF,

for allowing me to work in the Rio Doce State Forestry Park. Dr.

Cello Valle, Ilmar Bastos Santos, and Gustavo A. B. da Fonseca were

very instrumental in helping me to obtain my scientific expedition

visa to conduct research in Brazil. Celio Valle and Gustavo

Fonseca were more than helpful throughout the various stages of

fieldwork and allowed me to work in the mammalogy laboratory in

Belo Horizonte. Gustavo Fonseca was more than generous in sharing

his computers with me. Dr. Wilson Mayrink and his excellent staff

treated me in a concerned and professional manner. I thank them

for saving my nose.

The professional staff at the Rio Doce State Forestry Park

contributed to the project in several ways. Ademir Camara Lopes,

the park Administrator, helped us get settled into the Park. He

offered no cost housing for the duration of the project and

contributed a modest amount of the Park's gasoline supply for my

use in the project. He also was able to obtain funds from IEF for

the construction of arboreal platforms and 60 wire traps.

Hermogenes Ferreira S. Neto was extremely important in solving

daily problems and in handling our correspondence. Jose Lourenco

Ladeira, the park dendrologist, identified the shrub and tree

species that occurred within each trapping post. I am very

grateful for his participation and was amazed at his knowledge of

the taxonomy.










I thank Drs. Phil Myers, Mike Carleton, Guy Musser, Al

Gardner, and James Patton for identifying the voucher specimens.

Their prompt reply enabled me to begin the analysis shortly after

returning to the states.

I relied on several workers from the Rio Doce park to

implement the field project. Trails were opened in an expert

manner by Ivanil Moreira and Waldemar Queroga dos Santos. Ivanil

later became my field assistant and proved to be an extremely

valuable asset. He never once complained because of the incredible

numbers of ticks or because of all the small mammals that bit

chunks out of his fingers. I also thank Lidair Rufino for climbing

42 trees and placing the arboreal platforms.

Several students from the Departamento de Ecologia and

Zoologia participated in the fieldwork. I was aided greatly in the

data collection by 3 students. I thank Ludmilla Aguiar, Eduardo

Lima Sabato, and Luiz Paulo de Souza Pinto. I could not have

collected the appropriate data without their help. I also thank

Sonia Riquiera for her effort in helping us adjust to Minas Gerais,

and for participating in the initial stages of the fieldwork. She

was a pleasure to work with and always brought a positive attitude

to unpleasant working conditions.

My stay in Brazil was greatly facilitated by Gustavo and Ana

Fonseca. Their hospitality was more than generous and they always

opened their door to me and my family. Their hospitality was more

than "mineiro", it was more of true friendship. My wife and I will










always be grateful to all that the Fonsecas did to help us get

adjusted in Brazil.

To my wife and best friend, Cathie, I offer my deepest

gratitude for her patience, understanding, and moral support during

the 12 month field project. It was always a pleasure to come home

from the field and be met by a smiling and positive person. I am

very appreciative for Cathie's participation in the project and

wish that she could have had more freedom to pursue her own

interests.

















TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS ........................................... ii
ABSTRACT ...................................................viii

CHAPTERS

I INTRODUCTION ......................................... 1

General Background ................................... 1
Study Organization .................................. 3

II SMALL MAMMAL INVENTORIES IN AN EASTERN BRAZILIAN PARK 5

Introduction ......................................... 5
Study Site ........................ ............ .... .... 7
Methods ............................................... 11
Results ........................................... 22
Discussion .............................. .............. 48

III TEMPORAL VARIATION IN TRAPPING SUCCESS OF
DIDELPHID MARSUPIALS IN AN EASTERN BRAZILIAN PARK ..... 57

Introduction ......................................... 57
Materials and Methods ............................... 58
Results ........................................... 66
Discussion .............................. .............. 81

IV SMALL MAMMAL ASSOCIATIONS AND MICROHABITAT
SELECTION IN AN EASTERN BRAZILIAN PARK ................ 88

Introduction .......................................... 88
Materials and Methods ............................... 89
Results ........................................ ....197
Discussion ............................................ 114

V FOREST FIRE AS A DETERMINANT OF SMALL MAMMAL
DIVERSITY IN A BRAZILIAN FOREST .......................122

Introduction ..........................................122
Materials and Methods .................................126








Results ........................................ 138
Discussion .................................... 155

VI CONCLUSIONS AND SYNTHESIS ..................... 160

APPENDIX .............................................. 165
LITERATURE CITED .................................... 187
BIOGRAPHICAL SKETCH ................................... 200
















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

SMALL MAMMAL COMMUNITIES IN AN EASTERN BRAZILIAN PARK

By

JODY R. STALLINGS

August 1988

Chairman: John G. Robinson
Major Department: Wildlife and Range Sciences
Forest Resources and Conservation


This dissertation examines small mammal communities in native

and non-native habitats in one of the largest remaining forested

tracts of land in the Brazilian Atlantic Forest. Small mammals

were live-trapped over a period of 12 months in grass, eucalypt,

and native forested habitats. Eucalypt and native forested

habitats were rich in rodent species, but marsupials were

numerically higher in terms of relative densities. Grass habitats

were rich in rodent species and were dominated by one rodent

species. Trapping success for marsupials was observed to increase

during the sharp dry season. Paucity of food resources may be the

factor responsible for the observed increase in trapping success.

The Rio Doce State Forestry Park has been subjected to frequent

crown fire in the recent past, and relatively little primary forest

remains. Marsupials may dominate in terms of abundance in this

viii








Park because of the large amount of secondary forest. Small mammal

species diversity was calculated from forest stands that were

burned completely to the ground, in stands that were burned in a

mosaic fashion, and in primary stands. Species diversity was found

to be higher in intermediately fire disturbed native forested

habitats in comparison to heavily disturbed and primary forested

habitats. Mosaic habitats, composed of both secondary and primary

forest series, offer suitable habitat to more species than either

secondary or primary forest stands alone.
















CHAPTER I
INTRODUCTION





General Backaround



The Atlantic Forest of eastern Brazil is one of the most

threatened ecosystems in the World due to intense alteration of the

forested habitat (Mittermeler et al., 1982; Fonseca, 1983).

Fonseca (1983) estimates that approximately 3 5X of the native

forest remains today, with most of the remaining forest patches

occurring in protected areas and on privately owned lands. These

remaining forests are composed of mixed stands of primary, and

mostly, secondary forest series. The impact of these isolated and

heterogeneous forests on the wildlife communities has not been

studied. Only preliminary surveys have been conducted for the

primates that occur in this region and the remaining vertebrate

fauna is poorly known. This study focuses on small mammal

communities in a variety of habitats in one of the largest

remaining protected areas in the Atlantic Forest of eastern Brazil.

This study examines temporal and spatial variation in small mammal

communities in a region severely threatened by human activities.










2

The notion of prevailing stable environmental conditions in

the tropics helped to support the belief that tropical species

exhibit less temporal variation in reproduction, activity, and

feeding than temperate species. A current body of data reveals

that the tropics are much more dynamic than previously believed

(e.g., Leigh et al., 1982). This is especially true of tropical

areas that experience pronounced wet and dry seasons. The

Brazilian Atlantic region has such pronounced seasons. With this

in mind, this study investigated the effect of time on the trapping

success of small mammals.

Habitat structure has been shown to affect the species

composition and relative abundance of small mammals in forested

(Dueser and Shugart, 1978; August, 1984) as well as in non-

forested systems (August, 1984; Lacher et al., in press; Lacher and

Alho, 1988). Tropical forest small mammals form a diverse group

that has a varied diet, use of vertical space, and activity time.

In addition, South American small mammals can be composed of two

large groups, rodents and marsupials, in comparison to North

American communities. These factors will be taken into

consideration in determining how these small mammals allocate the

available space and resources in forest stands of differing

structure.

In some forest communities, disturbances can help to increase

floristic diversity (Connell, 1978; Horn, 1974). Connell (1978)

suggested that intermediate disturbances promote species diversity

in tropical forests and in coral reefs. This pattern has not been










3

observed for tropical vertebrate fauna, however, the relationship

is intuitive. Early secondary and primary forests are

characterized as spatially homogeneous, while forests disturbed in

an intermediate fashion are spatially heterogeneous. Forest series

characterized by a high degree of spatial heterogeneity should

provide more resources for more species in comparison to relatively

homogeneous environments. This study investigated small mammal

communities in a variety of forest habitats that were affected by

forest fire.



Study Ornanization



This dissertation is divided into four major chapters. Each

chapter reads as an independent paper, but all of the chapters have

a common theme. The theme is the small mammal communities in the

Rio Doce State Forestry Park in eastern Minas Gerais, Brazil. This

Park lies in the Rio Doce Valley and is part of the highly

endangered Atlantic Forest system of eastern Brazil. The primate

fauna of this region is highly endemic and very endangered

(Mittermeier et al., 1982). Inventories of other mammal species

are lacking for this region, although, preliminary species lists

indicated a highly endemic small mammal fauna.

Chapter II is concerned with intensive small mammal

Inventories in this park. This chapter describes the major habitat

types that were sampled, the sampling methodology, the effect of

trap position and type, and the small mammals that occurred in each










4

major habitat type. Chapter II sets the stage for the subsequent

chapters.

Chapter III examines the temporal variation in trapping

success of marsupials. Many species of small mammals have a

"window of vulnerability" or a period of time during the year when

they are trapped with greater frequency. This chapter addresses

this question by examining the pattern of trapping success of

didelphid marsupials through time.

The fourth chapter addresses the effect of habitat structure

on the use of space by small mammals. I sampled small mammal

communities in 5 forested habitats. Individual species were

compared by their use of vertical space, diet, and time of

activity.

Chapter V examines the effect of forest fire in structuring

the small mammal communities in the Rio Doce Park. Tropical forest

fire has not been recognized as a determinant of species diversity.

In this chapter I suggest that even a low frequency fire can set

back succession in a forest system that may require 300 years to

reach "climax" conditions. Fires in humid forests can occur

because of unseasonably dry periods that produce optimal conditions

for intense crown fires. Gaps or patches produced by fires can

affect species diversity of small mammals. Disturbances of an

intermediate fashion, such as fire mosaics, should increase species

diversity because it produces a mixture of successional series that

are suitable for a number of small mammal species.
















CHAPTER II
SMALL MAMMAL INVENTORIES IN AN EASTERN BRAZILIAN PARK



Introduction

In comparison to its geographical size, few studies have been

conducted on small mammal communities in Brazil. Most published

reports on Brazilian mammals are preliminary species lists (e.g.

Avila-Pires and Gouvea, 1977) or inventories (e.g., Vieira, 1955;

Moojen, 1952). Some Brazilian studies have focused on densities

(Emmons, 1984), others have focused on abiotic effects on small

mammals (Borchert and Hansen, 1983; Peterson, in press), while

others have addressed such diverse subjects as plantation effects

(Dietz et al., 1975) and public health needs or mammals that carry

human diseases (e.g., Laemment et al., 1946; Botelho and Linardi,

1980; Dias, 1982).

Recently, work in Brazil using mark-release techniques has

addressed the use of space, longevity, diversity and social habits

of small mammals (see Alho, 1982). As Alho (1982) pointed out,

most of these studies were concentrated in the xerophitic Cerrado

and Caatinga habitats. Fewer studies have been carried out in the

humid forests. Carvalho (1965) live trapped small mammals in a

tropical humid forest in Sao Paulo. Malcolm (pers. comm.) trapped

small mammals in tropical humid forest near Manaus, Amazonia.

5










6
Fonseca (pers. comm.) worked on small mammals in a range of

habitat types in eastern Minas Gerals.

The purpose of this paper is to report on intensive small

mammal inventories in a tropical humid Brazilian forest, the Rio

Doce State Forestry Park. This Park occurs within the geographical

limits of the highly endangered Brazilian Atlantic Forest (Fonseca,

1983). Small mammal inventories are lacking from this park.

Gastal (1982) and Avila-Pires (1978) report preliminary results

from intermittent small mammal inventories in the Rio Doce park.

The Brazilian Atlantic forest has a highly diverse flora and fauna,

with many endemic species of trees (Mori et al., 1981), reptiles

(Muller, 1973), and birds (Haffer, 1974). In-depth mammal

inventories in the region are lacking. The mammalian fauna is

poorly known. Mitterme1er et al. (1982) and Klnzey (1982) report

on the high level of diversity and endemism found in the primates

of the region. Preliminary species lists for non-volant mammals in

this region suggest a very high diversity and endemism (Cabrera,

1957, 1961; Honacki et al., 1982; Moojen, 1952; and Vieira, 1955).

For this project, a preliminary checklist was prepared of the non-

volant mammal species that probably occur in the Atlantic Forest

region (Table A-1). These data indicate that for the region there

are at least 131 species, 50 of which (39X) are endemic.










7

Study Site

Small mammal trapping was carried out in the Rio Doce State

Forestry Park (19 48'18" and 19 29'24" south latitude and 42

38'30" and 42 28'18" west longitude). The Park was created in 1944

at the request of Dom Helvecio, the bishop of the region (Gilhaus,

1986). The State Forestry Institute of the state of Minas Gerais

is the present administrative body.

The climate of the Park is classified as tropical humid

(Gllhaus, 1986) with a seasonal pulse of precipitation from

November through February and a pronounced dry season from June

through August. Average annual rainfall for a 20 year period

(CETEC, 1981) was 1480 mm, although the rainfall recorded during

this year of the study was considerably less (Figure 2-1). Mean

annual temperature averages 22 C (CETEC, 1981) and mean minimum

monthly temperatures vary greatly throughout the year (Figure 2-2).

The Park boundaries on the north and the east are two rivers,

the Rio Piracicaba and the Rio Doce, respectively (Figure 2-3).

The southern and western boundaries abut plantations of Eucalyptus

spp. forests.

The predominant relief forms in the Park are hills originating

from fluvial plane dissection and valleys derived from fluvial

deposits (Gilhaus, 1986). The altitude in the Park varies from 230

to 515 m. CETEC (1981) reports that 21% of the Park is composed of

plains, 40% undulating to strongly undulating hills and 34%

strongly undulating hills to mountainous terrain.






































WALTER AND LEBTH
CUMATIC DIAGRAM
MONTHLY RAINFALL (MM) MEAN TEMPERATURE ( )
400[- *0
3 120
300 1
250
200
180



JAN FEB MAR APR MAY JUN JUL AUG SEP OOT NOV oE8
MONTHS
AVERAGE ANNUAL RAINFALL 1480 mM


OATA PRU *964-'474


:ALTER AND LEITH
CLUMATC DiA'3RAM
MONTHLY RAINFALL fMM.) MEAN TEMPERATURE O )
*C3r----------------- 0
360 120
300 100
20 80
ZOO

1 60 4"
,r, i0
AN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MONTHS
ANNUAL AVERAGE RAINFALL 804 mne
ATA PROM I086-1Oe


Figure 2-1. Walter and Leith climatic diagram characterizing
precipitation surplus and drought per month in Rio Doce State
Forestry Park, Minas Gerais, Brazil. A= data collected for a
twenty year period (1954-1974) and B= data collected during
study.














MEAN MINIMUM & MAXIMUM

TEMPERATURES


TEMPERATURE (C)


25


-I


NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP O(
MONTHS


MEAN MAXIMUM TEMP


MEAN MINIMUM TEMP


DATA FROM 1954 1974













Figure 2-2. Temperature graph showing pronounced decrease in
minimum temperature during June, July, and August in Rio Doce State
Forestry Park, Minas Gerais, Brazil.


-- I


15


I


CT






















RIO DOCE STATE
FORESTRY PARK






LEGEND
lake

0\ river
stream
road
..::i... boundary ...
sites
:::::::::::..... burned areas

"": : -: eucalyptus









0 1 2 3 4 km














Figure 2-3. Map of Rio Doce State Forestry Park, Minas Gerais,
Brazil. Numbers circled indicate trapping sites.









11
A unique feature of the Rio Doce State Forestry Park (PFERD)

is the system of Rio Doce Valley lakes that occur there. There are

approximately 40 lakes and numerous marshes in the Park (Saijo and

Tundisi, 1985). According to Saijo and Tundisi (1985) the lakes

were formed by damming the drainage river of the Rio Doce

watershed. The marshes in the Park are the result of the

sedimentation of previous lakes.

The vegetation of the park is classified as tropical semi-

deciduous (Gilhaus, 1986). Most of the emergent tree species lose

their leaves during the cool dry months (J. Stallings, per. obs.).

Forest fire has been a major threat to the vegetation and wildlife

in the park because of the litter that accumulates during the dry

season. In 1964 and 1967, major fires burned approximately 30Z of

the park (Lopes, 1982; Silva-Neto, 1984).

Gilhaus (1986) described 5 forested and 5 open/field habitats

for the Park (Table 2-1). All of the forested and open/field habitats

have been altered to some extent by fire, with the exception of the

Tall Primary Forest with Epiphytes.



Methods
I live-trapped small mammals in 4 general habitas types: (1)

homogeneous eucalypt forest, (2) eucalypt forest with native species

subcanopy, (3) wet meadow, and (4) native forested habitats. I

trapped in 5 sites within the native forested habitat type. Two of

the sites (RD/C and RD/T) were primary forests and corresponded to

the Gilhaus (1986) classification of Tall Primary Forest with










12

Epiphytes. Two other sites (RD/H and RD/M) were altered by forest

fire in 1967 and burned in an intermediate fashion which produced a

forest mosaic of short, secondary and tall forest. This habitat type

corresponded to the Medium to Tall Forest with Bamboos and

Graminoids (Gilhaus, 1986). The remaining site (RD/F) was burned

completely to the ground in 1967 and the resulting vegetation type

corresponded to the Medium Secondary Forest with Bamboos and

Graminoids (Gilhaus, 1986).

The wet meadow habitat (RD/B) corresponded to both the Low

Woodland and Low Tree and Scrub Tallgrass Savanna classified by

Gilhaus (1986). This habitat type occurs between the edge of

permanent marshes and secondary forest. Grasses from the family of

Graminae are the dominant vegetative cover and were introduced in

the region as food for cattle.

The eucalypt forest with native subcanopy habitat was planted

with Eucalyptus salina in 1954 after the original vegetative cover

was removed. The eucalypt forest was harvested selectively in 1964

and again in 1971. However, the eucalypt forest was never clear-cut

and the native species were allowed to regenerate, largely through

coppicing, and developed into a complex native subcanopy. The result

is a homogeneous eucalypt upper canopy and a native species

subcanopy or "mata su.a." Tall exotic grasses cover the ground.

Emergent eucalypt trees reach 20 m in height.

The homogeneous eucalypt forest was first planted with

Eucalyptus salina in 1954 and was harvested 3 times on a 7 year

rotation. There is no native woody herbaceous subcanopy, only










Table 2-1. Forested and open/field habitats that occur in the Rio
Doce State Forestry Park, Minas Gerais, Brazil. Definitions and
characteristics of habitats taken from Gilhaus (1986).



COMPARISON TO
HABITAT TYPE % TOTAL THIS STUDY


FORESTED

TALL PRIMARY FOREST
WITH EPIPHYTES

TALL FOREST

MEDIUM TO TALL FOREST WITH
BAMBOOS AND GRAMINOIDS

MEDIUM SECONDARY FOREST WITH
BAMBOOS AND GRAMINOIDS


LOW SECONDARY FOREST

OPEN/FIELD

LOW WOODLAND


LOW TREE AND SCRUB TALLGRASS
SAVANNA

TALLFERN FIELD

EVERGREEN TALLGRASS FIELD
WITH TYDha SD.

PARTIALLY SUBMERGED
SHORTHERB FIELD
AND
AQUATIC HABITAT


RD/C, RD/T
PRIMARY FOREST


8.4

30.0


30.6


17.2


RD/M, RD/H
MOSAIC FOREST

RD/F
LOW SECONDARY
FOREST


RD/B
WET MEADOW

RD/B
WET MEADOW


3.0




8.9
100.0









14

eucalypt trees. Tall exotic grasses are the dominant ground cover.

Eucalypt trees reach approximately 15 m In height.

Individuals were snap trapped in order to obtain voucher

specimens, dietary, and reproductive information. Snap trapping was

carried out exclusively in wet meadow and secondary succession

habitats. All specimens were either preserved in 10X formalin or

made into museum study skins with corresponding complete skulls. I

also made study skins of individuals of species of uncertain taxonomic

status that were live trapped in habitats other than those where snap

trapping was carried out.

I placed one line of terrestrial Sherman live traps in the

homogeneous eucalypt habitat. Twenty-five Shermans, baited with dry

oatmeal, pineapple chunks and cotton balls soaked with cod-liver oil,

were opened for 4 consecutive nights on 5 occasions through the

study. Trap stations were separated by 15 m.

In the wet meadow habitat, live trapping started in February,

1986, and continued at monthly intervals through January, 1987. I

used two parallel trapping lines in this habitat. Each line was 280 m

in length and subdivided into 20 trap stations separated by 15 m. All

traps were placed on the ground, with even numbered stations having

only one Sherman live trap while odd numbered stations had one

Sherman and one locally made small wire live trap. Bait was

identical to that used in the homogeneous eucalypt forest.

In the eucalypt forest with native subcanopy and the native

forested habitats, the trapping design was identical (Table 2-2). In

each area, I cut 3 parallel lines 300 m in length through the forest.










Table 2-2. Trapping design used in native forested and eucalypt
forest with native species subcanopy habitats. Trapping lines are
A, B, and C. Numbers 1 16 represent trapping posts. Terrestrial
medium sized live traps = arboreal medium sized live traps = *,
small arboreal Sherman live traps = S, small terrestrial Sherman
live trap = s, large terrestrial live trap = L. Trapping lines
were separated by 100 m.


TRAPPING
STATION TRAPPING LINES


A B C


L:S


L:S


L:s


L:s


L:S



L:s


L:S



L' s


16 L:s










16

Sixteen trapping stations were placed along the line separated by 20

m. I used Sherman live traps and locally made small (15 X 15 X 30

cm) and large (25 X 30 X 60 cm) wire live traps. All traps were

placed within 3.5 m of the trapping post. All trapping posts had a

terrestrial small live trap. Odd numbered trapping posts had a small

wire live trap placed in a tree or bush. Mean arboreal live trap

height was 1.2 m. Odd numbered trapping posts had a Sherman live

trap alternating between arboreal and terrestrial positions. The

exterior trapping lines were identical with respect to number, kind

and placement of traps. I did not use the large live traps on the

interior line. Aside from the large live traps, the exterior and

interior lines were equal in trap number. However, the positions of

the Sherman and small live wire traps were reversed for the interior

line. The Sherman live traps were introduced into each of the

forested habitats after the study was well underway in an attempt to

sample smaller bodied species. I placed Shermans in two of the

native forested sites in January, 1986, and introduced Shermans in the

remaining forested sites in May of the same year.

I also experimented with traps that were placed high in the

canopy by a pulley and platform device. This method was similar to

that developed by Malcolm (pers. comm.) for use in the Brazilian

Amazon. Mean trap height was 11.2 m. I used these arboreal traps

to sample the canopy dwelling small mammals. Traps were located at

trapping posts along the established lines. The post and exact trap

location in each tree were determined in a subjective manner. I

placed traps in trees which I thought had a high degree of canopy










17

connectivity and upper stratum vine density. Forty-two arboreal

platforms were spread across 4 native forested sites. The primary

forest sites, RD/C and RD/T, and one of the mosaic sites, RD/H,

each had 12 arboreal traps, 4 traps per line. The other mosaic site,

RD/M, had only 6 traps because I did not believe that there was

sufficient upper strata development to support canopy dwelling

species. Arboreal canopy trapping started in June, 1986, and

continued through October, 1986. Trapping coincided with the

schedule developed for the terrestrial and arboreal trapping.

I used dry oatmeal, pineapple chunks and cotton balls soaked

with cod-liver oil for bait. Traps were set during the day and

remained open for 5 consecutive nights each month for one calendar

year.

The first occasion that an individual was trapped was considered

a first capture. The first capture plus subsequent captures of each

individual were considered total captures. Minimum known alive

(MKA) was the number of individuals actually captured each month

whether the capture was the first capture or a recapture from a

different session.

Trapping success of small mammals was calculated in the

following manner. I multiplied the number of traps by the number of

nights the traps were baited and armed per site per month to

determine the number of trap nights. Trapping success was the

number of individuals, MKA or total captures of all species divided by

the number of trap nights and expressed in percentages. For

example, if 100 individuals were trapped during 1000 trap nights, the










18

trapping success would be (100/1000) X 100 = 10X. Recapture indices

were calculated by dividing total captures by first captures and

indicated the average number of times an individual of each species

was captured.

I recorded the following information from each captured small

mammal: date, location on trapping line, position of trap, species, sex,

whether the trapped animal was a juvenile or adult, it's reproductive

condition, general condition, external parasitic load on a relative

scale, and behavior upon release. I also recorded standard body

measurements for each individual: body length, tail, ear, hind foot

and mass. I placed a numbered metal eartag in the left ear of each

individual upon the initial trapping of the individual.

Taxonomic determination of questionable species was made by

taxonomists specializing in various small mammal groups. Voucher

specimens were brought to the United States and the taxa were

distributed to the following people: cricetid rodents and marsupials of

the genus Marmosa were sent to Dr. Phil Myers, University of

Michigan; rodents of the subgenus Oecomvs were sent to Dr. Guy

Musser, American Museum of Natural History, and to Dr. Mike

Carleton, U.S. National Museum of Natural History.

I used body measurements, weight, reproductive condition and

pelage characteristics to determine the age class (juvenile or adult)

of each captured individual. An individual was considered an adult if

it was reproductively active. Female rodents were considered

reproductively active if they 1) had a perforated vulva, 2) were

pregnant, or 3) were lactating. Marsupial females were considered










19
reproductively active if they 1) were lactating or 2) had young

attached to the teat field. Male rodents were considered

reproductively active if the testes were descended. I could not

determine the reproductive status of male marsupials as the testes are

permanently descended. However, the activity state of the sternal

gland in marsupials can indicate the reproductive time of year.

Initially, I used the overall gestalt of each individual of each sex to

assign age classes. Later, I compared my initial classification with

the body measurements and mass. Body measurements and weights

were sorted for each sex of each species and plotted to determine if

recorded values could be grouped according to size. I then assigned

a body measurement value as the threshold for separating juvenile

and adult age classes. These age classes were then compared to the

initial age classes that were assigned in the field.

I used the General Linear Program (PC-SAS) ANOVA to test for

the equivalence of adult body measurements and mass means between

sexes for each species. This analysis enabled me to determine the

extent of sexual dimorphism for the external characters. Statistical

significance was set at 1 0.05.

Feeding categories were determined by stomach content analysis

(Charles-Dominique et al., 1981) and from the literature. I relied

heavily on information gleaned from the literature on food

preferences of small Neotropical mammals.

The use of vertical space (i.e., terrestrial, scansorial, or

arboreal) of each species was determined from 3 data sets. I

compared the proportion of captures in trees to that of captures on










20

the ground for each species. There were more terrestrial than

arboreal traps and this bias was corrected by adjusting the number of

total trapping opportunities. For this adjustment, I divided the

number of arboreal total captures by the total arboreal opportunities

(or total arboreal trap nights). The same was done for terrestrial

total captures. Results of these two divisions were summed and each

respective result (e.g., arboreal) was divided into the sum. The result

generated adjusted percentage success of arboreal and terrestrial

captures. The sum of total captures was multiplied by the adjusted

percentage in order to generate adjusted number of captures per

trapping stratum (on the ground or in arborescent vegetation). These

adjustments also were made for each species at each site as well as

pooled adjustments across all sites. I tested the null hypothesis that

there was no difference in the proportion of arboreal and terrestrial

captures for each species across all habitats as well as within each

trapping site. Prior to using Student's t-test, I arc-sin transformed

the proportions. I then compared the proportion of arboreal and

terrestrial responses upon release for each species across all habitat

types. These adjustments were made for all species in each habitat

type.

I used Student's t-tests to test the null hypothesis that there

was no difference in the locomotory response upon release of each

species. These 2 data sets were then compared to determine if there

were any differences between where an individual was captured and

its locomotory behavior upon release across all habitat types. These

tests also were performed for each habitat sampled. A species was










21

considered to be arboreal if that species was found to have a high

proportion of arboreal captures and a high proportion of arboreal

behavior upon release. The opposite would be true for a terrestrial

species. A species would be scansorial if there were no significant

differences in the proportion of spatial captures and no significant

differences in the proportion of behaviors exhibited upon release. I

then compared my results obtained from the trapping data to the

available literature for each species.

I also recorded the presence and relative abundance of other

vertebrates while walking the trapping lines in each sampling area.

Upon encountering an animal, I recorded the species, distance in

meters from the trail, height in trees for arboreal species, hour of

day, group size and other natural history data. I moved at a pace of

approximately 1 km. per hour and covered a distance of 1050 m per

sampling area. These walks yielded 60 km of repeat censuses per

sampling area. This method does not allow for the computation of H'

indices because it is difficult to ascertain the identity of individuals

being censused. Because of this problem, I only calculated species

richness per taxonomic group, number of encounters of each species

through time, and number of encounters of each group per linear km.

These data are presented in Table A-3.

I also superficially sampled the bat fauna of the Park. I

mounted mist nets in various habitat types (e.g., lake edge, secondary

habitat, primary habitats, and manmade structures) in order to

determine the species that occurred in the park. Nets were mounted

one hour before dusk and opened for approximately 4 hours each










22

night. Mist netting occurred on a sporadic basis. A species list of

bats obtained by these methods is presented in Table A-4.




Results
Species Accounts

I logged 1,308 captures of 17 species of small mammals in 40,490

trap nights. The small mammal fauna of the park consisted of 6

species of marsupials and 11 species of rodents. The diet, use of

vertical space and habitat requirements are presented in Table 2-3 for

each species captured during the study.

Marsupials Family Didelphidae.

Didelphis marsupialis Linne. (1758). The black-eared opossum

ranges widely in South America from the Isthmus of Panama to

southern Brazil. This species occurs sympatrically with D. albiventris

throughout much of its range (Streilein, 1982). In the Rio Doce

Valley, however, D. marsupials inhabits moister habitats, while D.

albiventris occurs in the cerrado vegetation (Valle and Varejao, 1981).

A. Gardner (pers. comm.) suggested that the form of D. marsupialis

found in eastern Brazil is distinct and should be referred to as Q.

azarae. This species inhabits brushy and forested habitats (Alho,

1982; Nowak and Paradiso, 1983). Miles et al. (1981) found this

species to be nocturnal, with a preference for nesting in tree

cavities. I captured this species in all forested habitats in the park

(Table 2-4). Adult body measurements do not indicate sexual

dimorphism (Table A-2). Females have a well developed pouch. This










Table 2-3. Ecological role played by each species captured during
this study in the Rio Doce State Forestry Park. GM= grasslands and
wet meadows, B= brushy areas, S= secondary forests, P= primary
forests, F= fossorial or semifossorial, SA= semiaquatic, T=
terrestrial, S= scansorial, A= arboreal, HG= herbivore-grazer; FG=
frugivore-granivore; FO= frugivore-omnivore; IO= insectivore-
omnivore. Taxa endemic to the Brazilian Atlantic rainforest or
the eastern coastal area of South America.


SPATIAL DIETARY
SPECIES HABITAT ADAPTATION CLASSIFICATION



MARSUPIALS
Didelphis marsupialis B, S, P T, S FO
Metachirus nudicaudatus S, P T IO/FO
Marmosa incana, B, S, P S IO
M. cinerea B, S, P A 10
M. microtarsus* S, P A IO
Caluromys philander S, P A FO

RODENTS
Oecomvs trinitatis S, P S FG
Orvzomys capito S, P T FG
Q. subflavus* GM, B, S T FG
0. nigripes* GM, B S FG
Akodon cursor* GM, B, S T IO
Calomvs laucha GM, B T FG
Nectomys sauamipes GM, B SA HG
Abrawavaomvs ruschii* S T FG?
Oxvmycterus roberti* GM, B, S F 10
Rhipidomvs mastacalis S, P A FG
Cavia fulgida* GM, B T HG
Euryzygomatomys soinosus* GM, B F HG










Table 2-4. Number of total captures and percent of total for each
species (SPP.) per habitat type. Numbers in parentheses represent
the percentage of captures per species per habitat percentages are
rounded to the nearest whole number.



SPP* HABITAT TYPES+


RD/F RD/H RD/M RD/T RD/C RD/E RD/B
DM 4 (3) 2 (1) 1 (1) 7 (6) 21(24) 7 (4)
MN 20(14) 44(16) 21(15) 30(23) 25(28) 18(11) -
MI 25(18) 75(27) 20(14) 28(22) 6 (7) 14 (9) 3 (1)
MC 74(52) 71(26) 69(49) 38(30) 31(35) 77(49) 1 (0)
MM 1 (0) -
CP 16 (6) 2 (1) 13(10) 3 (3) 15(10) 2 (1)
NS 6 (2) 9 (6) 5 (1)
RM 7 (6) -
AC 3(2) 46(17) 2(1) 1 (1) 25(16) 315(85)
OT 4 (3) 8 (3) 4 (8) 3 (2) 2 (2) -
OC 4 (1) 12 (9) 2 (2) 2 (1) 1 (0)
OS 12 (9) 1 (0) 31 (8)
ON 4 (1)
OR 1 (0) 2 (1) 4 (1)
AR 1 (0) -
CL 4 (1)
ES -2 (1)
142 276 142 128 89 158 373


+ RD/F= SECONDARY HABITAT BURNED COMPLETELY TO THE GROUND; RD/H=
SECONDARY HABITAT BURNED IN MOSAIC FASHION; RD/M= SECONDARY HABITAT
BURNED IN MOSAIC FASHION; RD/T= PRIMARY FOREST WITH LITTLE EFFECT
FROM FOREST FIRE; RD/C= PRIMARY FOREST; RD/E= EUCALYPT FOREST WITH
NATIVE SPECIES SUBCANOPY; RD/B= WET MEADOW.

* DM= DidelDhis marsupialis; MN= Metachirus nudicaudatus; MI=
Marmosa incana; MC= Marmosa cinerea: MM= Marmosa microtarsus; CP=
Caluromvs philander; NS= Nectomvs sauamipes; RM= Rhipidomys
mastacalis; AC= Akodon cursor; OT= Oecomvs trinitatis; OC=
Orvzomvs capitol; OS= Orvzomvs subflavus; ON= Orvzomvs nigripes;
OR= Oxvmvcterus roberti; AR= Abrawayaomvs ruschii; CL= Calomys
laucha; ES= Eurvzvyomatomvs spinosus.










25

species is terrestrial. There was a significant percentage of

terrestrial captures (Table 2-5) and terrestrial behavior upon release

(Table 2-6). I did observe several juvenile individuals and one adult

climb readily. Charles-Dominique (1983) reported that this species

exploits the lower stratum in forests, but can climb. This species is

basically an opportunistic feeder and feeds upon fruit and animal

matter (Charles-Dominique, 1983).



Metachirus nudicaudatus Geoffroy (1803). The brown four-eyed

opposum has a geographical distribution similar to that of 1.

marsupialis except that it is not found over much of Venezuela nor

in northeastern Brazil (Streilein, 1982). M. nudicaudatus can be

confused with Philander ODDosum as both have pale spots above the

eyes. In addition, there is considerable confusion over the taxonomy

of the two species. Nowak and Paradiso (1983) classified this species

as Philander nudicaudatus and Philander opossum as Metachirops

ODOSsum. I agree with Honacki et al. (1982) and follow their

classification. This species was captured in all forested habitats

(Table 2-4). Metachirus nudicaudatus is sexually dimorphic in its

mass and hind foot measurements (Table A-2). Females do not have

a pouch. This species is strongly terrestrial, rarely caught in

arboreal traps (Table 2-5) and rarely climbs upon release (Table 2-6).

Miles et al. (1981) found this species to be nocturnal and construct

nests on the forest floor or in ground hollows. There are very little

data on the feeding habits of this species due to the small numbers

that have been reported to be trapped. Preliminary data indicate










Table 2-5. Student's t-tests between adjusted and arcsin
transformed percentages of terrestrial and arboreal captures of
small mammals in all forest types. NS = non significant.


TERRESTRIAL
SPECIES CAPTURES


Didelphis marsupialis
Metachirus nudicaudatus
Marmosa incana
Marmosa cinerea
Caluromvs philander
Nectomvs sauamipes
Rhipidomvs mastacalis
Akodon cursor
Oecomys trinitatis
Oryzomys capito
Orvzomvs subflavus


66.6
76.3
43.9
27.8
16.3
69.6
28.8
83.5
31.2
62.9
58.0


X ARBOREAL
CAPTURES


23.5
3.9
46.1
62.2
73.8
21.0
61.1
6.3
58.8
27.0
32.5


V P<


40
156
169
356
49
17
5
390
19
19
46


.001
.001
NS
.001
.001
.05
NS
.001
NS
.05
.01










Table 2-6. Results of Student's t-tests between terrestrial and
arboreal behavior upon release of small mammals captured in all


habitats.
explained in


NS= non significant.
Table 2-4.


Species abbreviations


are


X TERRESTRIAL % ARBOREAL
SPECIES N BEHAVIOR N BEHAVIOR V T P <


DM 33 73.2 3 16.7 34 3.265 0.01
MN 150 80.7 4 9.1 152 4.934 0.001
MI 95 53.5 52 36.5 145 3.448 0.001
MC 11 10.8 294 78.9 303 7.743 0.001
CP 2 18.4 18 71.6 18 2.488 0.05
NS 12 90.0 0 0.0 10 10.882 0.001
RM 1 24.0 5 67.8 4 1.393 NS
AC 70 90.0 0 0.0 68 26.282 0.001
OT 9 64.8 2 25.3 9 1.763 NS
OC 13 90.0 0 0.0 11 11.326 0.001
OS 10 90.0 0 0.0 8 9.933 0.001









28

that this species is an insectivore-omnivore (Robinson and Redford,

1986) or frugivore-omnivore (Hunsaker, 1977).




Marmosa incana Lund 1840. This mouse opposum is endemic to the

Brazilian Atlantic Rainforest (Streilein, 1982). M. incana occurs in

both secondary and primary forest habitat. This species is small in

size (adults, average weight = 62 g) and strongly sexually dimorphic

in body size and color. Males tend to have larger ears and hind feet

(Table A-2) while females tend to have a more rose colored venter

and less pronounced face mask (P. Myers, pers. litt.). Females do not

have a true pouch. This species tends to use both the ground and

arborescent vegetation. I classify the spatial adaptation of this

species as scansorial (Table 2-3). There was no significant difference

in the proportion of terrestrial and arboreal captures (Table 2-5, p >

.90, df=169), however; individuals tended to remain on the ground

upon release (Table 2-6, p < 0.001, df=145). No data exist on the

feeding category of this species. Other species of Marmosa which

have similar body mass are classified as insectivore-omnivores.

Stomach content analysis (n=3) showed 100% insects from two orders,

Coleoptera and Orthoptera (Table 2-7). I classify this species as an

insectivore-omnivore based on the relationship found between body

mass and dietary classification (Robinson and Redford, 1986).








29

Table 2-7. Stomach content analysis of small mammals captured in
Rio Doce State Forestry Park, Minas Gerais, Brazil (N= number of
stomachs analyzed).



SPECIES FRUIT SEEDS GRASS INSECTS


Marmosa incana (n=3) 100%

Akodon cursor (n=23) 19% 19% 8% 52%

Orvzomys subflavus (n=1) 5% 95% -

Orvzomys nigripes (n=5) 34% 11% 21% 34%

Oxvmvcterus roberti (n=2) 100%

Calomys laucha (n=1) 100% -

Nectomvs squamipes (n=2) 50% 50 -









30

Marmosa cinerea Temminck (1824). M. cinerea has a disjunct

geographical distribution in South America; it occurs in northern

Venezuela through the Guianas, and It occurs In the Brazilian

Atlantic Rainforest extending into Paraguay (Streillen, 1982). M.

cinerea occurs in brushy and forested habitat, ranging from secondary

to primary. This species is a large bodied Marmosa (Table A-2,

average weight= 105g) and is highly sexually dimorphic based on

external body measurements. Males tended to have larger body, tail,

ear and foot (Table A-2). Females do not have a pouch. This

species is strongly arboreal and exploits the high forest stratum

(Charles-Dominique, 1983; Miles et al., 1981). Miles et al. (1981)

found this species to be nocturnal and to construct open arboreal

nests rather than use cavities. M. cnerea tended to be caught a

greater proportion of the time in arboreal traps (Table 2-5, p <0.001,

df=356) and tended to exhibit arboreal rather than terrestrial behavior

upon release (Table 2-6, p < 0.001, df=303). This species is primarily

an insectivore-omnivore (Robinson and Redford, 1986).



Marmosa microtarsus Wagner (1842). This species is restricted to the

Brazilian Atlantic Rainforest (Streilein, 1982). M. microtarsus differs

from its congener M. agilis by possessing a pure colored white patch

of hairs on the throat and chin (Tate, 1933). There are insufficient

data in the literature to determine if this species is terrestrial,

scansorial, or arboreal. I only recorded one capture during the study,

in an intermediately disturbed habitat (Table 2-4). However, the

species has a long prehensile tail and short wide feet which suggest










31
an arboreal lifestyle. This species is probably an insectivore-

omnivore.



Caluromys philander Linne (1758). This species has a disjunct

geographical distribution with populations in Venezuela, the Guianas

and northern Brazil and in southeastern Brazil (Streilein, 1982). The

woolly opossum is classified as a forest dwelling species (Nowak and

Paradise, 1983). This species was present in the eucalypt, mosaic,

and primary forested habitats (Table 2-4). Based upon the external

body measurements, there was no sexual dimorphism in adults (Table

A-2). Females lack a true pouch. According to Charles-Dominique

(1983) and Miles et al. (1981) this species exploits the high forest

stratum and is nocturnal. My data showed that there was a higher

proportion of arboreal captures (Table 2-5, p< 0.001, df=49) and that

this species tended to climb more than remain on the ground upon

release (Table 2-6, p < 0.05, df=18). Fruit makes up a large portion

of this species' diet (Charles-Dominique, 1983; Robinson and Redford,

1986).



Rodents Family Cricetidae

Oecomys (Oryzomys) trinitatus = (Q. concolor) Wagner (1845). This

genus is in need of revision and the subgenus Oecomys is currently

being revised (P. Myers, pers. comm.). This species was previously

called Orvzomvs concolor and was known, within Brazil, as an

Amazonian species (Alho, 1982). However, Nitikman and Mares (1987)

reported trapping this species in gallery forest in the Brazilian









32

cerrado. I captured this species in all native forested habitats (Table

2-4). The species is not sexually dimorphic (Table A-2).

Gyldenstolpe (1932) and Moojen (1952) stated that this species is

"more or less adapted for arboreal life." My data suggest that this

rat is scansorial; there were no significant differences in the

proportion of terrestrial and arboreal captures (Table 2-5, p < .10,

df=19) and no significant differences in terrestrial and arboreal

behavior upon release (Table 2-6, p < .20, df= 9). Most species of

the genus Orvzomvs are frugivore-granivores (Robinson and Redford,

1986).



Orvzomvs subflavus Wagner (1842). This species is distributed

throughout the Gulanas, southeastern Brazil and eastern Paraguay

(Honacki et al., 1982; Alho, 1982). In Brazil, it occurs in the

cerrado, caatinga and Atlantic Rainforest (Alho, 1982). This species

was captured in wet meadow and heavily disturbed secondary habitat

(Table 2-4). There were no differences in body measurements

between sexes in adult individuals (Table A-2). I classify this species

as terrestrial. This species tended to be captured more on the

ground than in the trees (Table 2-5, p < 0.01, df=46) and was never

observed to climb upon release (Table 2-6). Stomach content analysis

(n=1) showed 95% grass and 5% fruit (Table 2-7).


Oryzomys capitol Olfers (1818) = Q. goeldi, laticeos and intermedius.

This species has a wide distribution throughout the Neotropics and

occurs in a variety of habitats ranging from agricultural fields









33

(Moojen, 1952) to humid forests (Alho, 1982). Orvzomvs capitol was

primarily captured in humid forests ranging from intermediate levels

of disturbance to primary forests in the park (Table 2-4). There

were no significant differences in body measurements between sexes

for adults (Table A-2). My capture and release data are in

accordance with Alho's (1982) classification for this species. Q.

capito tended to be caught more on the ground than in trees (Table

2-5, p < 0.05, df=19) and tended to remain on the ground upon

release (Table 2-6, p < 0.001, df=11).


Orvzomvs (Oliiorvzomvs) niarioes (eliurus) Wagner (1845). This

small-bodied rodent (Table A-2) occurs in grassland, wet meadow and

secondary forest habitat in northern Argentina, eastern Paraguay,

southern Brazil and the Bolivian Beni (Honacki et al., 1982). In the

park, all captures were made in the wet meadow habitat (Table 2-4).

All captures were made on the ground (n=4), however; the individuals

climbed readily in captivity (J. Stallings, pers. obs.). The results

from the stomach analysis (n=5) revealed a wide range of foodstuffs

(Table 2-7).




Abrawavaomys ruschii Cunha and Cruz (1979). This species is only

known from the type locality in Espirito Santo, eastern Brazil. It is

endemic to the Brazilian Atlantic Rainforest. The single capture of

this species was recorded in an intermediately disturbed forest (Table

2-4). There is very little information available regarding the ecology










34

of this species and there are only three study skins found in

museums (A. Gardner, pers. comm.).



RhiDidomvs mastacalls Lund (1840). Climbing mice range south from

Margarita and Tobago Islands to Venezuela and Gulanas to

northeastern and east central Brazil (Honacki et al., 1982). This

species was only captured in a relatively undisturbed primary forest

(Table 2-4). Sample size was too small to detect any differences

between terrestrial and arboreal captures and behavior upon release.

However, as the common name implies, this species climbs readily. I

captured two individuals in my house in the park, a commonly cited

"exotic" habitat for this species (Nowak and Paradiso, 1983).



Nectomvs sauamipes Brants (1827). The neotropical water rat occurs

in aquatic habitats either in grasslands and wet meadows or in

forests. This species distribution ranges from the Gulanas to

Colombia to Peru and in Brazil, Paraguay and northeastern Argentina

(Honacki et al., 1982). This species tended to be caught more on the

ground (Table 2-5, p < 0.05, df=17) and exhibited a significant

tendency to remain on the ground upon release (Table 2-6, p < 0.001,

df=10). Stomach content analysis (n=2) showed 50% grass and stems

and 50X fruit (Table 2-7).



Akodon cursor Winge (1887). This species occurs in several habitat

types from southeastern and central Brazil to Uruguay, Paraguay and

northern Argentina. The wet meadow habitat in the park was the










35

primary habitat to capture this species (Table 2-4). A. cursor was

formerly included in A. arviculoides (Honackiet al., 1982). This

species is sexually dimorphic in tail (p < 0.01) and body (p < 0.008)

length (Table A-2). A. cursor is strongly terrestrial (Table 2-5 and

Table 2-6). Analysis of stomach contents (n=23) revealed a high

proportion of insects, seeds and fruit (Table 2-7).



Calomys laucha Olfers (1818).. This species occurs in grassland and

wet meadows in southern Bolivia, southeastern Brazil, Paraguay,

central Argentina and Uruguay. I only captured this species in the

wet meadow habitat in the Park (Table 2-4). The results from one

stomach sample revealed 100% seeds (Table 2-7).



Oxvmvcterus roberti Thomas (1901). The burrowing mouse occurs in

a variety of habitats but is usually associated with moist substrate in

open or brushy habitats. I captured this species in wet meadow and

secondary habitats in the Park (Table 2-4). This species is endemic

to eastern Brazil. This semifossorial mouse is described as an

insectivore (Nowak and Paradisio, 1983). Stomach analysis (n=2)

revealed 100% insects (Table 2-7).


Family Caviidae

Cavia fulaida Wagler (1831). This species of cavy is endemic to the

open grasslands and wet meadows of the Atlantic Rainforest of

eastern Brazil (Honacki et al., 1982; Nowak and Paradiso, 1983). I

captured this species in grassland and wet meadow habitats in the










36

Park, however; it was not trapped in site RD/B. For this reason this

species does not appear in Table 2-4. Cavies are terrestrial and are

herbivore-grazers (Nowak and Paradiso, 1983).



Family Echimvidae

Eurvzvqomatomvs soinosus Fischer (1814). The single species of

guiara is endemic to southeastern Brazil, Parguay and northeastern

Argentina (Honacki et al., 1982). I captured this species in the wet

meadow habitat (Table 2-4). This species inhabits open grasslands

and wet meadows, is considered terrestrial or semifossorial (Alho,

1982), and is most probably a herbivore-grazer.



Trapping results

Tables 2-8, A-5, and A-6 present the capture results by species

for the three main habitat types: native forested, eucalypt with

native species subcanopy and wet meadow habitats, respectively. As

a group, marsupials represented 79.2% and 83.3X of first and total

captures, respectively, in native forested sites, and 67.7% and 82.9% in

eucalypt forest with native species subcanopy. Rodents represented

97.3% and 98.4% of the first and total captures, respectively, in the

wet meadow habitat.

In the native forested habitat, Marmosa cinerea represented over

40% of the marsupial captures (Table 2-8), while in the eucalypt

forest, this species represented more than 58% of the marsupial

captures (Table A-5). Akodon cursor was the major contributor to

the rodent captures in all three habitats. This species only









Table 2-8. Capture results from native forested plots in Rio Doce
State Forestry Park, Minas Gerais, Brazil. RECAP INDEX= total
captures/first captures, and represents the average number of times
that an individual of species X is captured. Numbers in
parentheses represents percent of contribution of capture per
species per taxonomic group. Species abbreviations are explained
in Table 2-4.



TOTAL FIRST RECAP
SPECIES CAPTURES % TOTAL CAPTURES % TOTAL INDEX


MARSUPIALS

DM 35 4.5 ( 5.4) 32 7.8 ( 9.9) 1.1
MN 140 18.0 (21.6) 91 22.3 (28.1) 1.5
MI 154 19.8 (23.8) 90 22.1 (27.8) 1.7
MC 283 36.4 (43.7) 92 22.5 (28.4) 3.1
MM 1 0.1 ( 0.2) 1 0.2 ( 0.3) 1.0
CP 34 0.4 ( 5.3) 18 4.4 ( 5.5) 1.9
647 83.2(100.0) 324 79.4(100.0)

RODENTS

NS 15 1.9 (11.5) 9 2.2 (10.7) 1.7
RM 7 0.9 ( 5.4) 3 0.7 ( 3.6) 2.3
AC 52 6.7 (40.0) 27 6.6 (32.1) 1.9
OT 21 2.7 (13.8) 19 4.7 (22.6) 1.1
OC 18 2.3 (13.8) 15 3.7 (17.9) 1.2
OS 13 1.7 (10.0) 7 1.7 ( 8.3) 1.9
OR 3 0.4 ( 2.3) 3 0.7 ( 3.6) 1.0
AR 1 0.1 ( 0.8) 1 0.2 ( 1.2) 1.0
130 16.8(100.0) 84 20.6(100.0)










Table 2-9. Trapping success of
type in Rio Doce State Forestry


small mammals calculated by habitat
Park, Minas Gerais, Brazil.


NUMBER OF NUMBER OF
HABITAT TYPE TRAP NIGHTS CAPTURES % SUCCESS


NATIVE FOREST
(EXCLUDING PLATFORMS)
30,960


NATIVE FOREST
PLATFORMS ONLY

WET MEADOW

EUCALYPT FOREST
W/NATIVE SPECIES
SUBCANOPY

EUCALYPT FOREST
W/NO SUBCANOPY
TOTALS


710


66


1,050

1,980



6,000


500
40,490


373



158


1
1,308


2.3


6.3

18.8



2.6


0.0










39

represented about 7X of the total captures in the native forested

habitat, but 40% of the rodent captures (Table 2-8). In the eucalypt

forest, A. cursor represented about 16X of the total captures and 93%

of the rodent captures (Table A-5). This rodent was the dominant

species captured in the wet meadow habitat, representing about 85%

of both the total and of the rodent captures.

In both the native and eucalypt forested habitats, marsupials in

general were recaptured at a high rate. Didelphis marsupialis and

Marmosa microtarsus both showed low recapture rates and reflect the

small sample size. Especially noteworthy was the relatively high

recapture rate of Marmosa cinerea (Tables 2-8 and A-5). No

individuals of other species, neither rodent nor marsupial, were

recaptured as frequently as individuals of this species. In the native

forested habitat, individuals of M. cinerea were recaptured on the

average 3.1 times, while in the eucalypt forest, individuals of this

species were recaptured on the average 7.7 times.

Akodon cursor was the only rodent that had a relatively high

number of captures and recapture rate (Tables A-5 and A-6). This

species had a recapture rate of 1.6 and 3.0 in the eucalypt and wet

meadow habitats, respectively.

Trapping success

Table 2-9 presents the trapping success by habitat type.

Trapping success was calculated for small mammals in the native

forested habitat. The platform trapping data was excluded. It must

be kept in mind that the sampling effort in each general habitat

category was different, however, comparisons of trapping success are











COMPARISON OF TRAPPING
SUCCESS IN THREE HABITATS
PERCENT SUCCESS


40 F


20f


/ L


^-^-^\7


NOV DEC JAN FEB MAR APR MAY
MONTHS


JUN JUL AUG SEP OCT


- EUCALYPT


SWET MEADOW


-- NATIVE FOREST


Figure 2-4.
three habitat
forest in the


Comparison of trapping success of small mammals in
types: eucalypt forest, wet meadow, and native
Rio Doce State Forestry Park, Minas Gerais, Brazil.


4>










41

the result of the number of captures relative to the number of

trapping opportunities or nights. Overall, the wet meadow habitat

yielded the highest trapping success (18.8X) while the homogeneous

eucalypt habitat generated the lowest trapping success (0.02%).

Figure 2-4 compares the progression of the trapping successes of

the native forested habitat (without the platform data), the wet

meadow habitat and the eucalypt forest with subcanopy habitat.

Although these three habitats have unequal sampling effort and

trapping design, these habitats were sampled for the period of one

year and show important temporal trends. From the overall gross

comparison portrayed in Figure 2-4 and the percent success presented

in Table 2-9, in contrast to the wet meadow habitat, it appears that

the forested habitats, both native and exotic, were quite similar in

overall percent success and monthly trapping success. The wet

meadow trapping success fluctuated greatly throughout time, from a

high approaching 45% in March and April, to a crash lower than 10X

in May, October, and November.

I plotted the total captures, minimum known alive and first

captures through time for each of the three habitats. Figure 2-5

shows the capture curves for the native forested sites. Trapping

success was relatively low and stable from November through April,

with a noticeable increase in June, July and the early part of August.

This peak in trapping success dropped back to the levels observed

prior to the increase. Figures 2-6 and 2-7 compare the trapping

success of the eucalypt forest and the wet meadow habitat,

respectively. The highest number of captures at any one time in the



















CAPTURE CURVES FOR ALL
FORESTED SOTES


NUMBER OF CAPTURES


NOV DEC JAN FEB MAR APR MAY JU JUL A SEP
NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP


OCT


MONTHS
-TOTAL CAPTURES MKA CAPTURES -*-FIRST CAPTURES






Figure 2-5. Small mammal capture curves for all native forested
sites in Rio Doce State Forestry Park, Minas Gerais, Brazil.
Capture curves include total captures, minimum known alive (MKA),
and first captures.

















CAPTURE CURVES FOR
RD/E EUCALYPT SITE


NUMBER OF CAPTURES


0 --1-- 1--1---1- '1------:44-- -- --
NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT
MONTHS
TOTAL CAPTURES MKA CAPTURES +- FIRST CAPTURES








Figure 2-6. Small mammal capture curves for eucalypt forest in
the Rio Doce State Forestry Park, Minas Gerals, Brazil. Capture
curves include total captures, minimum known alive (MKA), and
first captures.














CAPTURE


RD/B WET MEADOW S1TE


NUMBER OF CAPTURES


DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT
MONTHS


TOTAL CAPTURES


-- MKA CAPTURES


* FIRST CAPTURES


Figure 2-7. Small mammal capture curves for wet meadow habitat
in the Rio Doce State Forestry Park, Minas Gerais, Brazil.
Capture curves include total captures, minimum known alive (MKA),
and first captures.


0O
NOV


CURVES


FOR










Table 2-10. Trapping success by trap type for all species in all
habitat types. Trap types are arranged according to trapping
location: terrestrial or arboreal. Trap types are as follows: 1ST=
small terrestrial Sherman live trap; 3MT= medium sized terrestrial
live trap; 5LT= large terrestrial live trap; 2SA= small arboreal
Sherman live trap; 4MA= medium sized arboreal live trap; 6PA=
arboreal platform trap.



NO. NO. PERCENT
TRAP TYPE CAPTURES TRAP NIGHTS SUCCESS


TERRESTRIAL
1ST 370 4080 9.1
3MT 553 18000 3.1
5LT 42 5760 0.7
965 30480 3.2

ARBOREAL
2SA 48 2640 1.8
4MA 228 8640 2.6
6PA 66 1050 6.3
342 12330 2.8










46

wet meadow habitat was double the highest in the eucalypt forest.

However, the trends were similar. Both habitats showed two

pronounced peaks in their respective capture curves that corresponded

to the same months throughout the year. There was a peak in

February, March, and April followed by a crash, and another peak in

June, July, and August followed by another crash.



Trap Types

Overall, trapping success was higher with terrestrial traps than

with arboreal ones (Table 2-10). Caution should be used in these

comparisons as the number of trap nights are unequal; almost three

times the number of terrestrial trap nights as the number of arboreal

ones. However, I feel that some degree of comparison can be drawn

from this analysis based upon the number of captures relative to the

number of trap nights.

Trapping success by trap type varied considerably (Table 2-10).

Small terrestrial Sherman live traps were the most successful (9.1%),

medium terrestrial traps represented the trap with the greatest

number of captures and trapping opportunities. and large terrestrial

live traps were relatively unproductive.

Arboreal trap type success varied. Small arboreal Shermans

were the least productive arboreal trap type with only 1.8% success.

The arboreal platform traps had a trapping success of 6.3%.

Table 2-11 reports the number of total captures of each species

and the number of captures per trap type. Odd numbered traps

represent terrestrial traps and even numbered ones represent arboreal










Table 2-11. Trap response by species across all habitat types.
Trap types are explained in Table 2-10. Species abbreviations are
explained in Table 2-4.


SPECIES


TRAP TYPES


DM
MN
MI
MC
CP
MM
NS
RM
AC
OT
OC
OR
AR
OS
CL
ON
EG
TOTALS
PERCENTAGES


TOTAL 1ST 2SA 3MT 4MA 5LT 6AP

42 0 0 24 2 15 1
158 0 0 129 3 26 0
171 13 14 106 38 0 0
361 2 29 145 150 0 35
51 0 0 9 13 0 29
1 0 0 0 1 0 0
19 4 0 13 1 1 0
7 0 0 3 3 0 1
392 312 2 78 0 0 0
21 1 3 9 8 0 0
21 8 0 11 2 0 0
10 7 0 3 0 0 0
1 0 0 0 1 0 0
44 18 0 20 6 0 0
2 2 0 0 0 0 0
4 3 0 1 0 0 0
2 0 0 2 0 0 0
1307 370 48 553 228 42 66
28.3 3.7 42.3 17.4 3.2 5.0









48

traps. In general, the number of captures per species in terrestrial

and arboreal traps represented the spatial adaptation for each species.

For marsupials, Didelphis marsupialis and Metachirus nudicaudatus

were captured principally in terrestrial medium live traps (3MT),

while Marmosa incana was captured in all trap types except for the

large terrestrial and arboreal platform traps. Marmosa cinerea was

captured in all trap types except the large terrestrial traps.

Caluromys philander was trapped principally in arboreal medium live

traps and arboreal platform traps. The sample size for rodents was

too small to allow for a clear trapping trend. Akodon cursor is the

clear exception. The small terrestrial Sherman live trap was most

effective for this species. This was mostly a consequence of the

approximately 80X of all Akodon captures made in the wet meadow

habitat (Table 2-10). Orvzomvs subflavus was trapped principally in

terrestrial small shermans and medium live traps.



Discussion

The trapping success realized in this study for neotropical humid

forests falls within the range of observed success rates (Table 2-12).

However, one striking difference between this and other neotropical

small mammal studies was the high number of marsupial captures

relative to rodent captures (Table 2-12). All reported studies show

rodent biases, and usually high captures of rodents relative to

marsupials. Only Emmons (1984) reported a marsupial to rodent

capture ratio approaching equality (Table 2-12). Fonseca (pers.

comm.) reported marsupial biased trapping results from a variety of










Table 2-12. Percent capture by taxonomic group, trapping success
and number of trap nights by habitat type for this study compared
to other Neotropical field studies. % M= percent of total
marsupial captures; X R= percent of total rodent captures; % T.S.=
percent trapping success; # T.N.= number of trap nights.



STUDY SITE % M % R % T.S. # T.N.


NATIVE FOREST


THIS STUDY
DIETZ ET AL., 1975
CARVALHO, 1965
EMMONS, 1984
EMMONS, 1984
EMMONS, 1984
DIAS, 1982
NITIKMAN & MARES,
1987
LAEMMENT ET AL.,
1946
AUGUST, 1984
DAVIS, 1945
FLEMING, 1972
1974
O'CONNELL, 1979


BRAZIL
BRAZIL
BRAZIL
PERU
PERU
BRAZIL
BRAZIL

BRAZIL

BRAZIL
VENEZUELA
BRAZIL

PANAMA
VENEZUELA


WET MEADOW/SAVANNA/PANTANAL


THIS STUDY
AUGUST, 1984
AUGUST, 1984
LACHER & ALHO,
IN PRESS
BORCHERT & HANSON,
1983
O'CONNELL, 1981


BRAZIL
VENEZUELA
VENEZUELA

BRAZIL

BRAZIL
VENEZUELA


2.0
0.0
25.0


98.0
100.0
75.0


0.0 100.0

0.0 100.0
10.0 90.0


HOMOGENEOUS EUCALYPT FOREST


DIETZ ET AL., 1975
THIS STUDY


BRAZIL 83.0 17.0


83.2
9.3
0.3
48.0


2.3


16.8
90.7
99.7
52.0


97.7


30.7 69.3


2.3

3.6
6.9
7.0
0.8


6.0

10.0
0.9


16.0


30,960

10,080
2,987
4,390
434


12,170

30,000
30,269


24,732


31.0
25.0
17.0


69.0
75.0
83.0


19.0 81.0
12.0 88.0


18.8
1.9
0.1

4.2

3.5


1,980
3,660
4,400

3,582

4,173


BRAZIL
BRAZIL


EUCALYPT FOREST WITH NATIVE SUBCANOPY


0.0 100.0
0.0 100.0


0.2


500
500


THIS STUDY


2.6 6,000










50

native forest sites in eastern Minas Gerais. Avila-Pires (1978)

captured 245 rodents and 40 marsupials from the Rio Doce Park.

Gastal (1982) reported that 5 species of marsupials were captured in

the Park but gave no comparative data for rodents. Dias (1982)

trapped more rodents than marsupials in the Rio Doce Valley in

Minas Gerais.

Hunsaker (1977) stated that marsupials require considerable

effort to trap. Perhaps one explanation for the observed high

marsupial/rodent capture ratio could be due to the habitat type found

in the Park. There is very little primary habitat in the Park relative

to secondary habitat (Table 2-1). Most of the forest habitat in the

Park has been altered by fire in the recent past (Lopes, 1982). The

primary forest plots that I sampled yielded the lowest species

richness and absolute captures of didelphid marsupials relative to the

other secondary forested habitats (J. Stallings, in prep.). Charles-

Dominique (1983) suggested that didelphid marsupials can reach high

local densities in areas of abundant food resources. He postulated

that these species are r-strategists and are adapted to the "unstable

environment of secondary forests." In Panama, Didelphis marsupialis

tended to occur at higher densities in primary forest, while

Caluromvs and Philander were found at higher densities in secondary

forest than primary forest (Fleming, 1972).

Marsupials were recaptured with great frequency in this study,

especially Metachirus nudicaudatus, Marmosa incana and Marmosa

cinerea. My recapture data on marsupials agree with data reported

by Fleming (1972, 1973), August (1984) and to some degree with that










51

found by O'Connell (1979). My data do not agree with Hunsaker

(1977) who stated that didelphid marsupials are difficult to recapture.

For example, individuals of Marmosa cinerea were captured on the

average 7.7 times in the eucalypt forest with native subcanopy

habitat. This high recapture rate could be explained by the fact that

this habitat in effect was surrounded by habitat unsuitable for

arboreal species. In essence, this habitat was a forested island. On

one side there was a monoculture of Eucalyptus salina with no

subcanopy, on another a marsh turned into a rice field, and the other

two sides of the forest were bounded by pasture. Arboreal species

should spend more time in arborescent vegetation than on the ground.

These species should be more hesitant to disperse than terrestrial

ones.

Another obvious difference between this study and other

inventories conducted in neotropical native forests was the absence of

echymid rodents. Species of the genus Proechimvs are the most

widespread taxa of the family Echymidae in the neotropics

(Hershkovitz, 1969). These forest species are terrestrial and usually

appear on species lists from forest inventories. In Panama,

Proechimvs was a common forest capture (Glanz, 1982; Eisenberg and

Thorington, 1973). Handley (1976) reported Proechimvs as a common

species in Venezuela. Emmons (1984) and Terborgh et al. (1986)

reported captures of Proechimvs from forested sites in Peru and

Ecuador. There are several reports of Proechimvs captures in

Brazilian tropical moist forests. Laemmert et al. (1946), Emmons

(1984), Carvalho (1965), Miles et al. (1981) and Malcolm (pers. comm.)










52

reported Proechimvs in their inventories from the Brazilian Amazon.

In the Atlantic Forest, Davis (1945) and Fonseca (pers. comm.)

reported two species of Proechimvs from their studies in the states

of Rio de Janeiro and Minas Gerais, respectively. Dias (1982) trapped

one species of Proechimvs in 3 study areas in the Rio Doce Valley.

I did not capture one individual of Proechimvs from the Park in

approximately 35,000 trap nights from 1985-86, nor from an additional

30,000 trap nights from 1986-87 (J. Stallings, in prep.). One

explanation could be the presence of predators in the Park.

Eisenberg (1980) speculated that the abundance of rodents in some

neotropical sites and the paucity of rodents in other sites could be

the result of the presence or absence of top predators. Hershkovitz

(1969) stated that species of the genus Proechimys "are the basic

source of protein for lowland predators in the Brazilian subregion."

The felid community in the Park is intact. All of the felids have

been observed by field workers in the recent past. I saw spoor from

jaguar, puma, ocelot, Geoffroy's cat, and jaguarundi.

In the wet meadow habitat my findings were consistent with the

literature (Table 2-12). In every other study, rodent captures were

higher than marsupial captures. In this study, Akodon cursor was the

dominant species in terms of absolute numbers and captures.

O'Connell (1981) reported that Zvgodontomvs was the dominant rodent

in grass habitat in Venezuela and represented 85X of the total rodent

captures. One difference between this study and others was the

observed high trapping success. As can be observed from Table 2-4,










53

Akodon cursor made up 85% of the captures and was responsible for

the high trapping success.

The eucalypt forest with native subcanopy habitat yielded

surprising results. I did not expect to find many small mammals in

this habitat because of "plantation effects." However, I captured 7

species of small mammals, most of these being marsupials. In fact,

the marsupial/rodent capture ratio was similar to that observed in the

native forested habitat (Table 2-12). I could not find any studies in

the literature to compare to the results from this habitat. Perhaps

the study that sampled homogeneous eucalypt forest would be the

most appropriate (Dietz et al., 1975). Dietz et al. (1975) captured

two species of terrestrial rodents, Orizomvs nigripes and Akodon

cursor, in the homogeneous plantations with grass/bamboo

undergrowth. The authors caught a total of 5 species, only one of

which was not strictly terrestrial, in the two native forested habitats.

The plantation habitats in this and my study are similar in that they

both were eucalypt plantations of similar age and that the terrestrial

substrate of both was covered by grass. The major difference was

the native species subcanopy. I captured a relatively high number of

terrestrial rodents and marsupials and a high number of arboreal

marsupials. I did not capture any arboreal rodents. The native

species subcanopy could be considered a secondary forest sere, if the

emergent eucalypt stratum is ignored. Following Charles-Dominique's

(1983) hypothesis of increased didelphid marsupial abundances in

secondary habitat, it is not surprising that I captured marsupials at a

rate consistent with the native forested habitat.










54

The temporal capture results suggested that there were two

systems operating in the Park. The trapping data showed a

pronounced peak in the total number of captures, mka and first

captures for the native forested habitat during the cool, dry winter.

Davis (1945) reported a similar trend in the trapping results and

suggested that this trend was the result of more younger individuals

present in the trapping pool or because of a paucity of natural food

items during this time of year. My data do not support the

hypothesis that more younger individuals explain the pronounced

increase; rather it appears that food resource paucity results in the

increase (Chapter III).

The eucalypt and wet meadow habitats showed similar trapping

trends with a peak in the cool, dry winter, and a peak in late

summer. These two habitats might have yielded similar capture curves

because of the grass substrate. Akodon cursor was an important

component of both habitats and is an insectivore/omnivore that is

reported to use a high proportion of grass and grass seed in its diet

(Nowak and Paradiso, 1983). Marmosa incana and Metachirus

nudicaudatus are insectivore/omnivores and frugivore/omnivores,

respectively, and perhaps track insect availability in grass substrate.

The grass species did not produce seeds until late May. Thus,

perhaps the peak observed in February, March and April can

be explained by the lack of food for both rodents and marsupials.

The second peak, which occurred in June, July, and August, could

also be explained in terms of a decrease in food availability. Insect

and fruit availability are usually low during the hibernal period in










55

seasonal neotropical forests (e.g., Janzen and Schonener, 1968). The

marsupial species rely heavily on these food resources. The results

of a preliminary stomach content analysis on Akodon, suggest that

insects are important items in this species diet (Stallings, in prep.).

Graminoids in this habitat were dry and seeds were not as readily

available as they were during April and May.

The trap type data analysis revealed that terrestrial small

Sherman live traps were very productive in the wet meadow habitat

but yielded relatively few captures in the forested habitats. The

same results were obtained for arboreal small Shermans in the

forested habitats. Large terrestrial live traps were unproductive in

the forested habitats. The most productive trap types were the

medium sized terrestrial and arboreal traps and the arboreal platform

traps. Some individuals of species that are considered terrestrial

were captured in arboreal traps. This can be explained by some low

arboreal traps that were connected to the ground by either a vine or

log.

The use of the arboreal platform traps did not allow me to trap

additional species that were not already trapped using the terrestrial

and low arboreal traps. However, I was able to increase the

frequency of capture of the highly arboreal marsupial Caluromvs.

Malcolm (per. comm.) obtained similar results with platform traps in

Manaus. Perhaps the first use of arboreal platforms for trapping

small mammals were in the studies described by Davis (1945) and

Laemmert et al. (1946). Unfortunately, I could not determine the

success of these traps nor the species captured from these studies.










56
In total, I logged 49 captures of this Caluromvs in both the eucalypt

with native species subcanopy and the native forested habitats. In

the latter habitat, I only trapped this species 5 times in the

terrestrial and low arboreal traps. I trapped 29 Caluromvs in the

native forested habitat by using the arboreal platforms. I would have

underestimated the presence of this species had I not used the

platform traps. Marmosa cinerea was trapped also with relative high

frequency in this trap type.

I was surprised to find such a high trapping frequency of

Caluromvs in the eucalypt forest with native species subcanopy.

Although this species can be quite common in native species forested

habitats, I found it unusual that this highly arboreal frugivore would

be inhabiting an exotic monoculture plantation. There obviously was

sufficient-food resources available from the native species subcanopy.

The fact that this species was captured in terrestrial and low

arboreal traps, without using platforms, suggests that this species was

using the subcanopy.

The results of this small mammal inventory suggest that

marsupials play an important role in the community structure of small

mammals in one of the largest remaining native tracts of Atlantic

forest in Brazil. Wet meadow habitat in this region is speciose in

rodents, and perhaps dominated by one or two species. Eucalypt

forests with native species subcanopy can play an important role in

the conservation of small mammal communities in a region greatly

altered by monocultural plantations.
















CHAPTER III
TEMPORAL VARIATION IN TRAPPING SUCCESS OF
DIDELPHID MARSUPIALS IN AN EASTERN BRAZILIAN PARK


Introduction

Tropical rainforests are classified as stable and evergreen, with

little seasonal change in the flora and fauna (Richards, 1952; Smith,

1974). However, tropical seasonal and semideciduous forests exhibit

seasonal changes in floral phenology (e.g., Augspurger, 1982; Foster,

1982; Garwood, 1982) and consequently variation in faunal populations

and activities (e.g., Howe, 1982; Worthington, 1982; Smythe et al.,

1982; Glanz et al., 1982). These changes have been related to

variation in the abiotic environment, such as changes in photoperiod,

precipitation, and temperature (Sinclair and Norton-Griffiths, 1979;

Leigh et al., 1982).

Tropical forests that exhibit a pronounced dry season seem to

have a peak of fruiting at the onset of the wet season immediately

following the dry season (Foster, 1980). While the reasons for this

peak in the fruiting period are not clear, the result is that fruit is

more abundant at certain times of the year. This increase in the

availability of fruit drastically affects the animals that use these

resources for food.

Population fluctuations interpreted by trapping results of small

mammals must be carefully analyzed to determine if the population is

57










58

actually fluctuating or if animals are responding to trap bait during

periods when food is available (Hunsaker, 1977). Previous research

on didelphid marsupials in the neotropics (Davis, 1945; O'Connell,

1979; Fleming, 1972, 1973; August, 1984) have found that trapping

success of marsupials increased during the hibernal and prevernal

months. This increase in trapping success has been attributed to the

paucity of food resources during this period. Another interpretation

of the results could be linked to reproduction, such as greater

movements of males or a large number of immatures. These might be

related to the initiation or the cessation of reproductive activity.

One objective of this paper is to test the null hypothesis that

trapping success of marsupials does not vary with season in the

Atlantic Forest of eastern Brazil. Another objective is to test the

null hypothesis that any peak in trapping success was a consequence

of an increase in the population or reproductive activities.

Materials and Methods

Small mammals were trapped from October, 1985, through

September, 1986, in the Rio Doce State Forestry Park, Minas Gerais

state, Brazil. The Park lies between the coordinates 19 48'18" and 19

29'24" south latitude and 42 38'30" and 42 28'18" west longitude. The

climate of the Park is classified as tropical humid with a rainy season

between the months of November and February and drought during

the months of June, July, and August. Mean annual temperature is

approximately 22 C, with mean minimum monthly temperatures

fluctuating greatly throughout the year (Figure 3-1). Both the mean

















MEAN MINIMUM & MAXIMUM

TEMPERATURES
TEMPERATURE (C)
35
30'
25 -
20
15 -
10 -













Figure 3-1. Temperature graph showing both minimum and maximum
mean temperatures per month in the Rio Doce State Forestry Park,
Minas Gerais, Brazil. Winter and summer seasons are indicated
along the X axis.










60
maximum and minimum monthly temperatures reach their respective

lows during the drought season.

For the purposes of this paper, I divided the year into two

seasonal periods. This division is based on the monthly mean

minimum temperature. If the mean monthly minimum temperature was

above 17 C. the month was classified as summer, otherwise it was

considered the winter period. A comparison of my seasonal

classifications and those of Davis (1945) shows thermal and intuitive

consistencies (Figure 3-1). My winter season corresponds to the

period from April September and the summer season from October -

March. My classification corresponds to those of Davis in the

following manner: my winter season includes the autumnal, hibernal

and prevernal seasons, while my summer season includes the vernal,

aestival and serotinal seasons.

The phytogeographical domain of the Park has been classified by

several authors. For example, according to Ab Saber (1977, in

Gilhaus, 1986), the Park occurs within the Tropical Atlantic Domain.

Rizzini's (1963, in Gilhaus, 1986) classification defines the Park's

domain as the Atlantic Province, Austro-Oriental sub-province,

Cordilheira sector. Gilhuis (1986) correctly pointed out that both

classification schemes locate the Park in a transitional zone bordering

the more humid Tropical Atlantic Domain and the drier Cerrados

Domain. I found tree species from both domains to be present in the

Rio Doce Park. Trees are more deciduous than would be expected in

Tropical Atlantic Domain forest. Most of the emergent tree species

and some others in the upper strata lose their leaves during the cool










61

and dry hibernal and prevernal seasons (Gilhuis, 1986; Stallings, pers.

obs.). The forest of the park is classified as Tropical Semideciduous

by Alonso (1977, in Gilhaus, 1986), Tropical Broadleaved by Azevedo

(1969, in Gilhaus, 1986) and Tropical Pluvial Seasonal by Lima (1966,

in Gilhaus, 1986).

Small mammals were live-trapped at 5 forested sites within the

Park boundary. Additional trapping was conducted in and around the

Park and the methodology is described in Chapter II. For the

purposes of testing the above mentioned hypotheses, I recorded the

following observations on each captured individual. The initial

capture of each individual was a first capture and a numbered ear tag

was placed on the left ear of all animals to identify individuals that

were captured previously. Total captures were first captures plus

subsequent captures of the same individual. The minimum known

alive (MKA) were the number of individuals captured on the first

occasion and those individuals recaptured only on one occasion during

each trapping period. Sex, age and reproductive information was also

recorded.

The probability of capturing a small mammal is affected by 3

factors: 1) temporal effects, 2) behavorial effects, and 3)

heterogeneity effects (White et al., 1982). The effects of

heterogeneity (e.g., number and placement of traps in an animal's

home range or variation due to social dominance) vary among animals,

but capture probabilities for each animal remain constant per

occasion. In contrast, temporal (e.g., variation over time because of

environmental conditions or trapping effort) and behavior (e.g., trap










62

avoidance or fascination) effects can alter capture probabilities after

the initial capture of an individual.

First capture data are more affected by heterogeneity and

temporal effects than behavioral effects (White et al., 1982). An

increase in the number of juveniles in first capture data through time

suggests that the population is increasing. However, if young

individuals do not account for an increase in first capture data, then

an alternative explanation is that the increase reflects individuals

present in the population that were not previously captured.

Total capture and minimum known alive data are influenced by

temporal, behavioral, and heterogeneity effects. Total capture data

are the result of all captures per occasion or through time, inclusive

of first captures, successive recaptures, and recapture of individuals

separated by time. These data should not be interpreted as a good

estimator of population abundance because they are strongly affected

by behavioral and temporal factors. An increase in recapture data

through time can be interpreted as a change in the capture

probabilities of marked individuals due to trap fascination, rather

than trap shyness which would reduce capture probabilities.

The minimum known alive data are the best population estimator

of the three. These data incorporate first captures and only the first

recapture of an individual captured in a previous occasion for each

trapping period. This estimator, in effect, uses the number of new

captures plus survivorship of animals captured previously to obtain an

estimate of abundance.










63

I only used marsupial capture data to test the null hypotheses

that trapping success does not vary by season and that any expected

increase is due to reproduction. Marsupials comprised 83X of the

total small mammal captures and 80% of the first captures (Chapter

II). Marsupial species included in the analysis were Didelohis

marsupialis (azarae), Metachirus nudicaudatus, Marmosa incana,

Marmosa cinerea, and Caluromvs philander. Fruit and insects are

important components of this group's diet (Chapter II).

I used correlation analysis and simple regression to determine if

there was any association between trapping success and mean

minimum monthly temperature. I quantified trapping success of first

captures, minimum known alive and total captures for each season.

Chi-square tests for goodness of fit were then used to test for

significant deviation from expected capture frequencies between

seasons.

I looked at (1) an increase in the number of juveniles during

the winter season, (2) an increase in the number of males between

seasons, (3) a male biased sex-ratio during the winter season, and (4)

an increase in the number of lactating/pregnant females during the

winter season to test the null hypothesis of an expected increase due

to reproduction. For this analysis I used Chi-square tests goodness

of fit to test for significant deviation from the above expected

results.

Individuals were placed into either juvenile or adult subjective

age classes. Initially, the age class placement was based on the

overall morphological gestalt of each individual per species. I then










64
used the recorded body measurements (Chapter II) to determine the

threshold between the two age classes and I compared field

determined ages to ages derived from body measurements. Body mass

and hind foot measurements were relied on heavily to determine age

class.

Age class categories of the 5 species of marsupials are presented

in Table 3-1 and are taken from Chapter III. For Didelphis

marsupialis. juvenile and adult age categories were based on the hind

foot size. This species can attain a body mass of 2 kg. The hind

foot would grow slower in comparison to smaller bodied species and

body mass would provide a better indicator of age. Animals with a

hind foot of 51 mm or smaller were classified as juveniles (average

weight 417 gm). Lengths greater than 51 mm (average weight 1049

gm) were classified as adults. I used body mass to determine the

threshold for Metachirus nudicaudatus, Marmosa incana, and Marmosa

cincera. These species are relatively small and foot size reaches its

maximum at an early age. Body mass provided the better estimator

because mass increased as the individuals grew older. Metachirus

nudicaudatus was placed into age categories based upon a threshold

weight of 90 gms. Age class placement was determined by a weight

of 35 gm and 50 gm for Marmosa incana and M. cinerea, respectively.

All Caluromvs philander that were captured were considered adults.

The number of individuals of each sex were sorted for first,

MKA, and total capture data between and within seasons.

Comparisons were made for sex biased trapping success between










Table 3-1. Criteria used to place marsupials into either juvenile
or adult age categories. Individuals per species were classified
as juveniles if designated measurements were less than cut-of
measurements used in table. Species were not sexually dimorphic
based on body measurements listed.



BODY CUT-OFF
SPECIES MEASUREMENT USED MEASUREMENT


Didelphis marsupialis HIND FOOT 51 MM

Metachirus nudicaudatus MASS 90 G

Marmosa incana MASS 35 G

Marmosa cinerea MASS 50 G










66

seasons for all capture data. In addition, comparisons were made for

sex biased trapping success within seasons.

Female marsupials were examined to determine if they were

lactating and for the presence of young attached to the teat field.

Females with young attached were considered pregnant. Frequencies

of lactating/pregnant females were compared on a seasonal basis.



Results

There was a significant negative association observed between

mean monthly temperature and trapping success through time. This

association is significant only if we look at the number of total

captures (f=28.444, p < .0003) (Figure 3-2) or the minimum known

alive (f=9.939, p < .007) (Figure 3-3). First capture data did not

show a significant association (Figure 3-4).

The first capture data (0.05
0.001) and total captures (p< 0.001) of marsupials were greater than

expected in the winter season than in the summer season (Table 3-2).

Juveniles were observed throughout the year. Juveniles were

represented from four of the five species of marsupials (Table 3-3).

There was no significant difference in the minimum known alive or

first captures of juveniles between seasons. A significant difference

(p < .001) was observed in the total captures of juveniles between

seasons. More total captures of juveniles were observed in the

winter season than expected.

The number of juveniles captured per species between seasons

was fairly constant (Table 3-3) from minimum known alive and first




















RELATIONSHIP BETWEEN
TEMPERATURE AND TOTAL CAPTURES

NUMBER OF CAPTURES
100
r'= .74
80

60 *

40

20

0 I-I I
0 5 10 15 20
TEMPERATURE (C )


Figure 3-2. Relationship between temperature and total captures
of didelphid marsupials in the Rio Doce State Forestry Park,
Minas Gerais, Brazil.













RELATIONSHIP BETWEEN
TEMPERATURE AND MKA CAPTURES
NUMBER OF CAPTURES


5 10 15 20
TEMPERATURE (C )


Figure 3-3. Relationship between temperature and
alive captures (MKA) of didelphid marsupials in
State Forestry Park, Minas Gerais, Brazil.


minimum known
the Rio Doce


















RELATIONSHIP BETWEEN
TEMPERATURE AND FIRST CAPTURES

NUMBER OF CAPTURES
"i-----------------------


40

30


20

10


10
TEMPERATURES )


Figure 3-4. Relationship between temperature and first captures of
didelphid marsupials in the Rio Doce State Forestry Park, Minas
Gerais, Brazil.


r2' .16

^----










Table 3-2. Comparison of the first captures, minimum known alive
(MKA) and total captures of five species of didelphid marsupials
between seasons in the Rio Doce State Forestry Park, Minas Gerais,
Brazil. Significant at 0.05-0.01. ** Significant at 0.01-
0.001.


SEASONS


WINTER SUMMER CHI-SQUARE



FIRST CAPTURES 206 151 4.23*

MKA CAPTURES 276 157 16.35**

TOTAL CAPTURES 392 190 35.05**








71

Table 3-3. The number of first captures (FIRST), minimum known
alive (MKA) and total captures (TOTAL) of juvenile didelphid
marsupials per season. N.S= Non significant.


SUMMER SEASON


WINTER SEASON


FIRST MKA TOTAL FIRST MKA TOTAL


SPECIES

Q. marsupialis 3

M. nudicaudatus 7

M. incana 15

8. cinerea _
TOTALS 33


FIRST CAPTURES

MKA CAPTURES

TOTAL CAPTURES


= 0.00,

= 0.55,

=14.38,


14


33


N.S.

N.S.

P < 0.001










72

capture data. The total capture data per species indicated that there

was a recapture bias during the winter season, although the

difference was not significant. Figure 3-5 shows that first captures

of adults, not juveniles, clearly represented the majority of captures

during May, June, and July.

The number of captures of each sex between seasons is

presented in Table 3-4. There were no significant differences

between the number of males captured between seasons or the number

of females captured between seasons using the first capture data.

Minimum known alive and total captures data showed significant

differences in the expected number of males or females between

seasons. More males and more females were captured during the

winter season than during the summer season, with a higher

proportion of males being captured during the winter season. For the

first capture data, minimum known alive and total capture data there

were no significant differences in the male/female sex ratio within

each season (Table 3-5).

More lactating females, whether carrying young or not, were

captured during the summer season than the winter season (Table

3-6). However, this difference, although approaching significance,

was not statistically significant (x2 =2.89; .10 < p <.05). One

striking observation was the obvious decrease in the occurrence of

lactating/pregnant females during the months of June, July and

August (Figure 3-6). This decrease is also observed when comparing

number of juveniles and lactating females per species through time

(Figures 3-7, 3-8, and 3-9).

















FiRST CAPTURES
OF ADULTS AND YOUNG BY MONTH
NUMBER OF CAPTURES


NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT
MONTHS


i NO. YOUNG


SNO. ADULT


Figure 3-5. Comparison of first captures of adult and young
didelphid marsupials per month in the Rio Doce State Forestry Park,
Minas Gerais, Brazil.










Table 3-4. Between season comparisons of the number of first
captures (FIRST), minimum known alive (MKA) and total captures
(TOTAL) of didelphid marsupials per sex. Significant at 0.05-
0.01. ** Significant at 0.01-0.001.


BETWEEN SEASON COMPARISON


SUMMER SEASON WINTER SEASON X2


NUMBER OF MALES

FIRST CAPTURES 62 83 1.52

MKA CAPTURES 78 152 11.90**

TOTAL CAPTURES 97 215 22.30**


NUMBER OF FEMALES

FIRST CAPTURES 66 70 0.05

MKA CAPTURES 79 124 4.98*

TOTAL CAPTURES 92 174 12.63**








75

Table 3-5. Within season comparison of the number of first
captures, minimum known alive captures (MKA) and total captures of
didelphid marsupials per sex. N.S.= Non significant. Significance
level set at p < 0.05.


SEX


SUMMER SEASON


FIRST CAPTURES

MKA CAPTURES

TOTAL CAPTURES


FIRST CAPTURES

MKA CAPTURES

TOTAL CAPTURES


MALES

62

78

97





MALES

83

152

215


FEMALES

66

79

92





FEMALES

70

124

174


0.06 N.S.

0.003 N.S.

0.06 N.S.







0.55 N.S.

1.42 N.S.

2.16 N.S.








76

Table 3-6. The frequency of lactating/pregnant didelphid
marsupials trapped per season in the Rio Doce State Forestry Park,
Minas Gerais, Brazil. N.S.= Non Significant.



SPECIES SEASONS


SUMMER WINTER


D. marsupialis 4 1

M. nudicaudatus 11 12

M. incana 9 0

M. cinerea 12 3

Caluromvs philander 1 3

TOTALS 37 19


















FREQUENCY


OF LACTATING


FEMALE MARSUPIALS


NUMBER


NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT
MONTHS


E Didelphis
P M. cinerea


E Metachirus
I O Caluromys


Figure 3-6. Comparison of lactating females of five species of
didelphid marsupials per month in the Rio Doce State Forestry Park,
Minas Gerais, Brazil.


= M. incana














FREQUENCY OF YOUNG,
AND LACTATING FEMALES
NUMBER


NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT
MONTHS


=- YOUNG


LACTATING FEMALES


M. nudicaudatus





Figure 3-7. Comparison of the number of captures of young and
lactating females of the didelphid marsupial Metachirus
nudicaudatus in the Rio Doce State Forestry, Minas Gerais, Brazil.

















FREQUENCY OF YOUNG
AND LACTATING FEMALES

NUMBER


NOV DEC JAN FEB MAR APR MAY JUN
MONTHS


! I YOUNG


JUL AUG SEP OCT
JUL AUG SEP OCT


= LACTATING FEMALES


M. Incana


Figure 3-8. Comparison of the number of captures of young and
lactating females of the didelphid marsupial Marmosa incana in the
Rio Doce State Forestry Park, Minas Gerais, Brazil.

















FREQUENCY


AND LACTATDNG FEMALES


NUMBER


NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT
MONTHS


] YOUNG


= LACTATING FEMALES


M. cinerea


Figure 3-9. Comparison of the number of captures of young and
lactating females of the didelphid marsupial Marmosa cinerea in the
Rio Doce State Forestry Park, Minas Gerais, Brazil.


OF YOUNhG














Discussion

There is obviously a connection between animal population

numbers and the availability of food resources (Leigh et al; 1982).

An intuitive model is that population increases should track and peak

with maximum production of food resources. By timing reproduction

prior to the peak of available food resources, individuals maximize

their opportunities for the survival of their offspring.

There was a clear peak in the trapping success of marsupials

during the winter months in the Rio Doce State Forestry Park.

There was a significant negative association between the number of

total captures or minimum known alive each month and mean

minimum monthly temperature. However, the first capture data did

not support these previous findings. These data suggest that the

recapture of individuals plays an important role in the trapping

success numbers and that the numbers of new individuals did not

increase during the winter season.

August (1984) found an increase in the capture success of

Marmosa robinsoni during the dry season in Venezuela, while

O'Connell (1979) reported an increase in the minimum known alive for

Marmosa robinsoni, M. fuscata, and DidelDhis marsupialis during the

same period in Venezuela. Fleming (1972) observed an increase in

the number of captures of three species of marsupials during the dry

season in Panama. Davis (1945) reported more captures and

recaptures of two species of didelphid marsupials, Didelphis










82

marsuDialls and Caluromvs philander, during the dry, cold season in

Teresopolis, Brazil.

Research on neotropical marsupial mating behavior suggests that

typically males are more active prior to and during the reproductive

or mating season (Atramentowicz, 1982; Hunsaker, 1977). This may be

a consequence of the polygynous mating systems observed for these

small mammals (Eisenberg, 1981). There was no significant difference

between seasons in the number of first captures of male marsupials.

The same results were obtained for female first captures. There were

more male and female minimum known alive captures during the

winter season than the summer season. The same results were

obtained for the total captures of male and female marsupials during

the winter season, but at a higher level of significance. These data

again suggest that there is a recapture bias in the trapping data, and

that observed and significant differences in the number of captures

and individuals of each sex between seasons is a function of being

recaptured and not related directly to reproduction. However, the

minimum known alive and total capture data show male captures in

the winter season to be more significant than females captures during

the same period. These findings could be interpreted as increased

male activity over female activity at the onset of the reproductive

season.

A direct measure of population growth is the number of young

observed at any point in time. My results indicate that during the

winter season the number of young individuals captured was not

greater than in the summer season, but more young individuals were










83

recaptured during the this season than in the summer season.

O'Connell (1979) reported an increase in the number of individuals of

Didelphis marsupia1is during the wet season in Venezuela. She

attributed this increase to the first captures of juveniles.

The last measure that was used to determine population growth

was that of the occurrence of lactating/pregnant females through

time. Statistically, there was no difference in the occurrence of

reproductively active females between seasons, although there was a

suggestion of more reproductively active females in the summer

season than in the winter season. O'Connell (1979) found that most

of the species she studied to be sexually inactive during the dry

season.

It is clear from the previous analyses that there was a

pronounced increase in the number of animals known to be alive and

the overall trapping success during the hibernal and prevernal seasons

(Figure 3-10). However, the data do not support the hypothesis that

this significant increase is due to more juveniles present in the

population, nor does it result from increased male activity or more

lactating/pregnant females. I conclude that population growth of

marsupials was constant if we consider only first capture data.

Clearly, the trapping success curve was being driven by adult

individuals; individuals that were being recaptured more during a

certain period in time than at another.

I did not measure the availability of fruit or insects during the

study. Phenological studies (CETEC, 1981) in the park from 1977-

1981 found that trees were in flower and fruit throughout the year,














FREQUENCY OF CAPTURES
BY SEASON
NO. CAPTURES
200


100

50


OCT-NOV DEC-JAN


FEB-MAR


APR-MAY JUN-JUL AUG-SEP


MONTHS GROUPED ACCORDING TO SEASON


SEASONS GROUPED BY MONTHS (DAVIS, 1945)




Figure 3-10. Frequency of captures of didelphid marsupials by
season in the Rio Doce State Forestry Park, Minas Gerais, Brazil.


1.....


150










85

with a noticeable, but not statistically significant increase from

October through December (Figure 3-11). These studies also Indicated

that the months of June, July and August represented the lowest

incidence of tree species with flowers and fruits. There was also a

low incidence of tree species with flower and fruits in January.

There are no quantitative data available on the seasonality of insect

density in the park. However, studies in other Neotropical areas

report a positive association between increased insect abundance and

precipitation and temperature (Janzen and Schonener, 1968; Wolda,

1978, in August, 1984; Davis, 1945). It is possible that such a trend

occurs in the park due to the high seasonality of rainfall and

temperature.

In other areas were neotropical didephids have been studied

(Fleming, 1972; O'Connell, 1979; August, 1984; Charles-Dominque,

1983), the dry season represented the period of the year when food

resources were scarce. In contrast, the three month period from

October December in the park showed more species in fruit and

flower than any other three month period. These trends are

interesting when compared to the low and peak three month trapping

success periods. The highest trapping success coincides with the

lowest number of tree species in fruit and flower and likewise the

lowest period of trapping success coincides with the maximum period

of fruit and flower production.

However, it must be stated that trapping success remained

relatively constant for the period of December and January when the

number of tree species with fruit and flower were observed to be
















FREQUENCY OF FRUIT
AND FLOWERS


NO. SPECIES IN FRUIT


OCT-NOV DEC-JAN FEB-MAR APR-MAY JUN-AUG AUG-SEP
SEASONAL PERIODS IN MONTHS


Figure 3-11. Frequency of species of trees and shrubs in fruit and
flower per seasonal period in the Rio Doce State Forestry Park,
Minas Gerais, Brazil.










87
low. This two month period has the highest mean temperature and

precipitation of the year. If insect density is high at this time, then

perhaps marsupials are able to switch to insect prey or other foods

in response to the unavailability of fruit.

I would interpret my results of a significant increase in total

trap success as a response to the lack of fruit during the subtropical

winter and not due to (1) greater movement of males (i.e., more

captures of males than females during this period) nor (2) a

significant increase in the number of juveniles captured nor (3)

because of more reproductively active females during this period.

Marsupials fell into traps easier during this period because they were

searching for food. This interpretation is consistent with the

findings of Atramentowicz (1982), Charles-Dominique et al. (1981),

Charles-Dominique (1983), O'Connell (1979), Fleming (1972, 1973),

Davis (1945) and August (1984) and suggests that reproduction and

weaning of young marsupials occur at the end or after the dry season

when food resources are more abundant.
















CHAPTER IV
SMALL MAMMAL ASSOCIATION AND MICROHABITAT
SELECTION IN AN EASTERN BRAZILIAN PARK

Introduction

There are several studies on small mammal habitat selection in

temperate zones (e.g., Dueser and Porter, 1986; Dueser and Shugart,

1978, 1979; Hallett, 1982; Rosenzweig and Winakur, 1969), but there

are relatively few small mammal habitat studies conducted in the

neotropics. August (1983, 1984) studied the relationship between

small mammals and habitat structure in Venezuela. Lacher and Alho

(in press) and Lacher et al. (1988) reported habitat selection by small

mammals in grassland habitats in southern Brazil. Nitikman and

Mares (1987) reported microhabitat preferences of small mammals in a

gallery forest in central Brazil. The purpose of this paper is to

examine the effect of habitat structure on habitat use by small

mammals in an eastern Brazilian forest, the Rio Doce State Forestry

Park.

Preliminary analysis of the habitat in this Park suggested that

there are distinct differences in the forest structure across several

forested habitats (Gilhaus, 1986). Forest fire, in the form of intense

crown fire, has played an important role, at least in the recent past,

in structuring the forest. This study tested the hypothesis that small










89

mammal abundances vary with habitat and that species select

microhabitats within each habitat.

Materials and Methods

This study was conducted in the Rio Doce State Forestry Park

(Rio Doce), Minas Gerais, Brazil (19 48' 18" and 19 29' 24" south

latitude and 42 38' 30" and 42 28' 18" west longitude). The Park

contains over 35,000 ha and elevation ranges from 230 to 515 m. The

mean annual precipitation for the Park was 1480 mm. from 1954 to

1974, however annual precipitation during the study amounted to 947

mm. (Figure 4-1). Mean monthly maximum and minimum temperatures

vary appreciably throughout the year (Figure 4-2).

Study Sites

There are several distinct forested and open/field habitats in the

Park (Gilhaus, 1986). Slope, soil quality and moisture, and elevation

all affect habitat type. However, forest fire has played the major

role affecting the forested habitat in this Park. The vegetation of

the Park is classified as tropical semi-deciduous and most of the

emergent tree species lose their leaves during the cool dry months.

In 1964 and 1967, major forest fires burned approximately 30X of the

forest (Lopes, 1982; Silva-Neto, 1984). Fire is important because leaf

litter accumulates during the dry season.

During the course of this study, I surveyed small mammal

communities in 5 distinct forested sites which represent 3 habitat

types in the Park (Figure 4-3). The following is a brief description

of each study site.












































WALTER AND LEITH
CUMATIC DIAGRAM
MONTHLY RAINFALL (MM) MEAN TEMPERATURE (0) 14
400 140
360 120

250 so
200 I O
180

00 20
00
JAN FEB MAR AP MAY JUN JUL AUG SEP OOT NO OE
MONTHS
AVERAGE ANNUAL RAINFALL U8O mm
a5 RnM ta-1SI" 4


WALTER AND LEITH
CUMATIC DIAGRAM


MONTHLY RAINALL (MMt)


MEAN TEMPERATURE (C


3o0 120
0100
ANNUAL
200
80
100

a 1
JAN FEB MA APO uA JUN JULL AUG SEP OCT it0 OE-.
MONTHS
ANNUAL AWEMAGE RAINFALL 80 mn
am FROM a101u-au


A. 5.










Figure 4-1. Walter and Leith climatic diagram characterizing
surplus precipitation and drought by month in the Rio Doce State
Forestry Park, Minas Gerais, Brazil.



















MEAN MINIMUM


& MAXIMUM


TEMPERATURES


TEMPERATURE (C )


DEC JAN FEB MAR APR MAY JUN JUL AUG SEP


NOV


OCT


MONTHS
MEAN MAXIMUM TEMP MEAN MINIMUM TEMP

DATA FROM 1954 1974



Figure 4-2. Mean minimum and maximum monthly temperatures in the
Rio Doce State Forestry Park, Minas Gerais, Brazil.


25
20
15


I I I-


()