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1997 Roost Site Selection of the Red Bat (Lasiurus borealis) Kenneth J. Mager Eastern Illinois University This research is a product of the graduate program in Zoology at Eastern Illinois University. Find out more about the program.
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uthor Date Roost site selection of the red bat (Lasiurus borealis)
(TITLE)
BY
Kenneth J. Mager
THESIS
SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
Master of Science
IN THE GRADUATE SCHOOL, EASTERN ILLINOIS UNIVERSITY CHARLESTON. ILLl~OIS
1997 YEAR
I HEREBY RECOMMEND THIS THESIS BE ACCEPTED AS FULFILLING THIS PART OF THE GRADUATE DEGREE CITED ABOVE
DATE Roost site selection of the red bat (Lasiurus borealis)
Kenneth J. Mager Masters Thesis
Eastern Illinois University
Charleston, IL ll
To my Mother, Father, and Sister,
I've got it covered!
Always, Ill
ABSTRACT
I monitored the roosting activity and evaluated roost site selection of red bats
(Lasiurus borea/is) at study sites in Coles County during the summer of 1996. Red bats
were mist-netted and radio transmitters were affixed to 12 individuals. A total of 105 transmitter-days were recorded with 75 roost locations identified. The roost types consisted of eight different species of trees, prairie grass, and residential structures but the vast majority of roosts (92%) were in Jarge, deciduous trees. The height of the roosts ranged from 0.5 to 21.4 m, but 54.7% were between 5-10 m. Movement between consecutive roosts ranged from 0 to 733 m with 80% being less than 200 m. Reduced understory vegetation beneath roosts allowed for a less obstructed flight path. Red bats showed fidelity to their home ranges, but not to individual roost sites. Urban forests in central Illinois provide the essential habitat components for successful coloniz.ation by bat species and may constitute important habitat for this species. IV
ACKNOWLEDGMENTS
I would like to thank Glenn Lyons of Fox Ridge State Park, Rick Goebel of Hidden
Springs State Forest, and Angela Smith of the Douglas-Hart Nature Center for their help
in implementing this study. I am grateful for the assistance from Susan Latta and
Stephanie Kavanaugh and to everyone else who spent long hours helping me in the field each night.
I would like to thank the Biological Sciences Graduate Program and the Council for
Faculty Research for funding of this project. I would also like to thank the faculty of the
Zoology Department for their encouragement and support. I am especially indebted to
Dr. Thomas Nelson, my advisor, for his encouragement and patience in this project. I am also grateful to his ftunily for their kindness and patience while using their house as a study area. I would also like to thank my committee members, Dr. Robert Fischer and
Dr. Eric Bollinger for their guidance, advice, and constructive input on this manuscript.
Finally, I would like to thank Alan Pilch, Ann Marie Hogan, Catherine Woodworth,
Dan Lloyd, Dave Gregory, and Andy Miller for their friendship, support, and encouragement during this project. v
TABLE OF CONTENTS
Title page ...... i
Dedication...... ii
Abstract ...... iii
Acknowledgnients...... iv
Table of contents...... v
Introduction...... 1
Methods ...... 4
Resuhs and Discussion...... 9
Conclusion and Management lmplications...... 15
Literature cited...... 16
Tables...... 20
Figures...... 25 fNTRODUCTION
Bats are an integral part of many ecological communities, and can be economically
important because they consume certain insect pests. Populations of many bat species
are declining worldwide, apparently due to loss of critical habitat, pesticides, and
harassment (Hill and Smith 1984). Unlike most small mammals, bats have difficulty
recovering from population declines because they exhibit low reproductive rates and
delayed sexual maturity (Barbour and Davis 1969). Among those species which may be
declining in Illinois are the four tree roosting species: red bats (Lasiurus borealis), hoary
bats (Lasiurus cinereus), silver-haired bats (Lasionycteris noctivagans), and Indiana bats
(Myotis soda/is). The latter is federally endangered (Hoffineister 1989).
It is difficult to monitor population status of tree-roosting bat species because they
are solitary, widely dispersed, and difficult to observe. However, it is reasonable to assume that habitat changes such as loss of forest due to urbanization and agriculture, forest fragmentation, and removal of mature trees, cavity trees, and snags (Kurta and
Teramino 1992) may have caused declines in these species in the Midwest. The potential impact of these activities on red bats is difficult to discern because relatively little is known about roost site selection by this species. To properly conserve red bats, a more detailed understanding of their habitat requirements is needed.
Tree-roosting bats typically roost in foliage, tree cavities or under loose bark. Red bats have been observed roosting in trees and shrubs (Hall and Kelson 1959). Daytime roosts generally include forest edge habitats adjacent to streams, open fields or urban areas. However, it has also been reported that red bats occasionally roost on or near the ground (Hall and Kelson 1959). Early studies suggested that tree-roosting bats select 2
roosts that provide deep shade, are visible from below, lack branches from which
predators might detect and attack them, are 1-3 m above the ground and are located
over ground cover that reduces reflected light (Constantine 1958, 1966). Further, roosts
may be selected because they provide thermal cover by reducing a bat's exposure to
light and wind or because they are located close to preferred foraging areas.
Selection of a suitable roost is vital for the survival of a migratory species since it is
essential for bats to locate roosts in unfamiliar territory. Constantine (1966) suggests
that an attracting odor remains with the roost after its use, or perhaps foraging bats
observe roost use by another bat and consider it acceptable for future use. This
hypothesis is supported by Downes' (1964) observations of five different red bats
selecting one sunflower as the preferred roost site over the other flowers in the row.
Therefore, it might be expected that these cues are used to reduce the time and energy
required to locate roosts. The ability of a red bat to switch and locate a new suitable
roost gives the bat access to a wider range of habitats. This in turn will reduce its
dependence on a particular area. Bats with alternative roosts are more likely to survive
possible destruction of their roosts (ie. environmental or human factors) compared to those species which rely on a single roost (Barclay et al. 1988).
Research has shown that red bats preferred forest edge habitat to dense, mature deciduous forests for roosting (Constantine 1966, Kunz 1973). Furlonger et al. (1987) found red bats more often in terrestrial edge habitats than similar edges associated with water. The reduced amount of canopy cover and understory which is provided by edge habitat reduces impediments for flight and foraging (Campbell et al. 1996). Intensive 3
agriculture and urbanization has lead to increased forest fragmentation in the Midwest
and has increased the amount of urban edge habitat available to bats. In the intensively
farmed "combelt" region of central Indiana, Illinois and Iowa, I speculated that these
islands of urban forests may constitute important roost habitat for tree roosting bats.
Therefore, I conducted a telemetry study to gather descriptive information on roost site
selection by red bats in Illinois. The purpose of the study was to describe habitat
requirements of this species so that proper conservation of the species can proceed. The
specific objectives were to: (1) find and describe daytime roosts of red bats, (2) estimate
distances between roosts used on successive days, (3) estimate proximity of roosts to
foraging sites, (4) conduct a dietary analysis, and (5) evaluate the importance of urban
forests as roosting habitat for red bats. My null hypothesis for this study was that roost
selection is random with no consideration to tree type or home range fidelity. Our
alternative research hypotheses were: (1) red bats will preferentially roost in large,
deciduous trees, (2) red bats will show site fidelity by occupying home ranges < 1 km2 , and (3) red bats will occupy urban forests because they provide mature trees for roosting and extensive forest edge habitat. 4
METHODS
Study Sites
The study was conducted at four study sites in east-central Illinois. Sites included
Hidden Springs State Experimental Forest in Shelby County, and Fox Ridge State Park,
Douglas-Hart Nature Center, and Sister City Park in Coles County (Fig. 1). Hidden
Springs and Fox Ridge contain predominately mature, deciduous, second-growth forests.
These sites are 486 ha and 686 ha in size, respectively. In contrast, the Douglas-Hart
and Sister City sites contain mixed deciduous and pine forests and open fields and are
only 14 ha and 7 ha in size, respectively. Sister City Park, which is a residential urban
park, was created with the expansion of Charleston's subdivisions into the surrounding
agricultural fields. The creation of this wooded area, along with the additional trees of
the neighborhood, has created an island of potential habitat suitable for small mammals
over the past 20 years.
Capture and Marking
All four sample sites were surveyed weekly for 1-2 hours after sunset to determine
the presence or absence of red bats. Areas sampled were usually chosen because they
appear to provided suitable foraging habitat, including open fields and streams or ponds
adjacent to forests. Surveys were conducted using a Mini-2 Bat Detector (Summit,
Inc.) set at 40 kHz to detect characteristic echolocation activity of foraging red bats
(Salcedo et al. 1995). Mist netting was conducted over 80 nights between May 20 and
September 30 1996, for a total of 192 net-nights. A net-night is defined as the number 5
of nets erected multiplied by the number of nights each net was erec t e d . I nc Iement
weather prevented netting on 17 nights. Nets were erected approximately o.s hr before
sunset and were monitored for at least 2.5 hrs to coincide with the period of greatest
foraging activity by red bats. A total of 432 hours were spent monitoring these nets.
Each net was 2 x 6 m in size and was suspended between poles in a flagpole manner
on lines suspended from pulleys at the top of each pole. Usually 2 nets were stacked
from 1.5 to 5.5 m above the ground. Nets were stretched across potential foraging
flyways, typically open fields, powerlines, wooded streams, or perpendicular to the edges
of ponds or forests (Kunz and Kurta 1988). A portable ultra-violet light was used on
some evenings to concentrate insects near the nets (Wilson 1965).
Once netted, bats were removed and identified to species. Red bats were
immediately processed, while other species were recorded and released. Red bats were
sexed based on the appearance of external genitalia (Anthony 1988), weighed using
spring scales accurate to 0.2 g, and aged based on epiphyseal-diaphyseal fusion (Anthony
1988). Individuals were marked for identification with distinctively colored, split-ringed
plastic bands (Land M Bird Bands, Inc.). In addition, radio-transmitters (Holohil
Systems Ltd; 150-151 Mhz) weighing 0.75 g were attached to 12 bats. Transmitters were glued to the back between the wings using Skin-Bond adhesive (Smith and Nephew
United, Inc.; Hickey 1992). Each transmitter had an expected transmission period lasting 21 days prior to battery failure. Bats were monitored and released once the transmitters were secured. The size and weight of transmitters used in this study were below what is usually considered to be acceptable for red bats (Bradbury et al. 1979, 6
Aldridge and Brigham 1988). All statistical calculations were conducted at an a. level
=0.05.
Radio-tracking and Roost Descriptions
Bats carrying radio-transmitters were tracked daily by progressively triangulating
their positions using a telemetry receiver and 3-element yagi antenna until each individual
was sighted (Wildlife Materials, Inc.). At each roost site, the tree species, tree diameter,
roost height, and roost orientation were recorded. Height of the roosting bat was
estimated with a clinometer, and tree diameter was measured with a steel diameter tape.
Roost locations were recorded using a OPS receiver (Trimble, Inc.) accurate to
approximately 10 m and then transferred to aerial photographs. A metric grid pattern
was overlaid on each aerial photograph so that each roost location could be recorded
using a coordinate system. These coordinates were used then to estimate linear distances
between roosts, and the home range size of each bat.
Home Range Analysis
For the purpose of this study, I defined a bat's home range as the area
encompassing all known roosting sites for an individual. Home range calculations were
conducted using McPAAL computer software for the analysis of animal location data
(Stuwe and Blohowiak 1986). Estimates were obtained using two methods: the
Minimum Convex Polygon (Eddy 1977) and Harmonic Mean Transformation (Dixon and Chapman 1980). I estimated home range first using the minimum convex polygon 7
because it creates an estimate for the entire range covered by the bat and because it is the
method most commonly reported in the literature. A range polygon is created with the
outer roost points acting as the vertices. The area is then calculated for the entire
polygon. However, most animals do not use their home ranges with equal intensity.
Therefore, we used the harmonic mean transformation to adjust for this occurrence. The
harmonic mean creates the smallest possible polygon around 90% of the roost locations
for each bat. This locates the center of activity and does not include areas used
infrequently
Dietary Analysis
A dietary analysis of red bats captured during this study was conducted by
identifying the contents of their feces (Whitaker 1988). The examination of red bat feces
provided by bats held briefly for processing is possible due to the rapid digestion,
processing and elimination of foods. Upon capture, each bat was placed in a holding
bag for 3-5 minutes before being processed and released. Feces eliminated by each
individual were removed and stored for analysis. The hardened exoskeletons of most insects, comprised of protein and chitin, will pass undigested through the digestive tract permitting identification of insect food items to Order. However, foods that are entirely consumed will be underrepresented in fecal analyses (Kunz and Whitaker 1983). Fecal pellets were softened by placing them in petri dishes of warm water. The individual pellets were teased apart with dissecting pins and were sorted into piles for identification
(Whitaker 1988). Two values can be calculated from this data: I) percent frequency, 8 the percentage of bats eating each food type, and 2) average percent volume, the percent volume of each food type in the total sample (Whitaker 1988). 9
RESULTS AND DISCUSSION
Bats Captured
During the study 275 individual red bats were detected and observed using the bat
detector. Four species were netted including 17 red bats, 2 hoary bats, 1 big brown bat
(Eptesicusfuscus), and 11 little brown bats (Myotis /ucifugus). Of the 31captures,30
occurred at Sister City Park, in a residential section of Charleston, and 1 red bat was
captured at Fox Ridge State Park. In addition, 20 bats at Fox Ridge were recorded
echolocating at 50 kHz. This is the typical frequency use by foraging Indiana bats
(Fenton and Bell 1981), and suggests that a small colony of this endangered species may
inhabit the Park.
The 17 red bats included 10 adult males (59%), 1 juvenile male (6%), 2 adult
females (12%), and 4 juvenile females (24%) (Fig. 2). The low frequency of capture of
adult females may be because adult females give birth in early June and carry their young
until they are too heavy to be supported in flight, thus restricting their foraging (Barbour and Davis 1969). Juvenile males tend to be captured less frequently because they are more nomadic and have a more erratic foraging pattern (Barbour and Davis 1969).
Although red bats were observed throughout the summer, 94% of our captures occurred between July 16 and July 31, with the remaining 6% between August 1 and
August 15. Red bats are usually solitary, decreasing the probability of multiple captures in one night. The temporal pattern of captures in our study was consistent with
Ho:ffineister's (1989) report that captures ofred bats statewide begin to increase in mid
June and continue towards a peak in August and early September. McClure (1939), 10
studying this species in a small Iowa town, reported that the greatest abundance of red
bats occurred between July 24 and August 7, and that none were observed in town after
August 20.
Capture rates were lowest in the largest forest tracts. The forested areas of Hidden
Springs and Fox Ridge required 120 net-nights per captured red bat. However, capture
rates were much higher (1 capture/2.4 net-nights) in the urban forest habitat represented
in this study by Sister City Park, perhaps because of increased forest edge. The
increased edge allows for a greater diversity and number of insect prey for these bats
(Lewis 1995).
Daytime Roosts
During the study, nine transmitters were available for attachment to bats. Twelve of the 17 captured red bats had a transmitter attached for some period of time. Two bats died during the study, and two others removed the transmitter after several days. These recovered transmitters were cleaned and attached to new bats. A total of 105 transmitter-days and 75 roost locations were recorded prior to September 30.
Red bats monitored during our study used a diverse array of roost sites including mature trees, dense grass, and the shingles of residential structures (Fig. 3). The majority of roosts (89%) were in large deciduous trees, but a preference for sweetgum trees was evident. Sweetgums were selected as roost trees 19% of the time, but they were less than 1% of the tree population. Oaks and hickories were used proportional to their occurrence, constituting 51 % of the roosts and 44% of the available roost trees I I
(Table 1). There was a significant influence of tree type on roost site selection (X.2
=285.5; d.f.=19). These results are generally consistent with McClure's (1942) observations that red bats seem to prefer trees which provide large, rough leaves and broad protective crowns. Red bats showed a preference for larger trees; nearly 80% of the roosts were in trees exceeding 30 cm in diameter, but this size group comprised only
34% of the available trees (Fig. 4). There was a significant influence of d.b.h. on roost site selection (X.2 =164.9; d.f.=6). These may provide greater roost cover. Roost heights ranged from 0.5 m to 21.4 m with 54.7% between 5 and 10 m above the ground, again emphasizing the importance of large trees as roost sites for red bats (Table 2).
In the majority (75%) of tree roosts, the bat hung within 1.5 m of the end of a branch with an open area beneath the roost (Table 3). This location may provide both thermal cover and protective concealment from predators. Thicker foliage towards the end of the branch provides the greater concealment, however this location may be more costly energetically due to increased convective heat loss (Hayward and Garton 1984).
The majority ofroost sites (59%) were located on Nor E aspects. The former are generally cooler and shaded from the direct rays of the summer sun. Wind velocity within the covered roosts may be 18-30% of the velocity outside of the roost with only a slight difference in air temperature between the inside and outside (Walsberg 1986). The apparent shielding from the wind is a major thermal benefit in selecting covered roosts.
These locations provide overhead cover from predators and precipitation, while allowing bats to take flight by dropping straight down from the roost. 12
Spatial Distribution of Roost Sites
Individual bats rarely used the same roost site on successive nights, but successive
roosts generally were within 300 m of each other. In this study, six bats (35%) reused 12
roost trees at later dates. Of the 61 movements 46% were less than 25m, while only 8%
were greater than 400 m (Table 4). The short distances between most roosts suggest
that red bats have a preference for a small roosting area or that suitable roosts occurred
in discrete patches. Switching roosts may be a response to changing environmental
conditions, since different microclimates are provided at different trees (Kunz 1982,
Kurta et al. 1993).
Home range size was calculated for 10 bats. Home range was calculated based on
an average of9 successive roost locations (range= 3-19). The average area calculated
by the minimum convex polygon was 0.9 km2, but 60% were less than 0.5 km2• Home
range size calculated using the harmonic mean transformation averaged less than 0.1 km2
(Table 5).
The small home ranges exhibited by red bats in this study are consistent with those
reported for other small bats. This may be because these species have precise habitat requirements that are met only in specific locations. Furlonger et al. (1987) suggested that urban bats may feed longer and over larger areas because feeding rates are lower due to lower insect densities. However, street lamps may concentrate insects offsetting this trend.
Red bats in this study showed a greater fidelity to their home range than to specific roost sites. Two studies of tree-roosting bats in the tropics reported that bats using tree 13
cavities showed fidelity to particular roost sites, while those using foliage roosts (which
are temporary and abundant) showed fidelity to their home range, but not to individual
roost sites. Morrison (1978, 1980) reported that the two tree-roosting species he
studied (Artibeus lituratus and Vampyrodes caraccioli) rarely used the same roost for
more than two consecutive days. However, Morrison (1980) stated that by remaining
faithful to a particular group of trees, the foliage roosting bats are more familiar with the
locations of roosts in dark recesses in foliage that are particularly well protected from
predators.
Jackson (1961) noted that individuals seemed to cover the same area each evening.
He found that they often foraged 600 to 1,000 m from their day roosts. Remaining faithful to a particular area allows the bats to benefit from site familiarity. The disk winged bats (Thyroptera tricolor) return to the same roosting area each day, even though the condition of their roosts (unfurling leaves) is such that they must find a new leaf nearly everyday (Findley and Wilson 1974). Individuals using cavities traveled nearly twice the distance to foraging sites compared to foliage roosting individuals. The trade-off for these bats appears to be reduced higher energetic costs for commuting to foraging areas versus increased security from predators and safe for developing offspring
(Lewis 1995).
Dietary Analysis
Fecal samples were collected from 16 of the 17 red bats captured, and these were examined for moth (Lepidoptera) and beetle (Coleoptera) remains. Moth remains were found in 63% (10/16) of these samples, whereas beetle remains were found in 44% 14
(7/16). The mean percent volume was 41.2% moths and 15.3 % beetles. A portion of each sample was too fine to be unidentifiable. These results are similar to Whitaker's
(1972) study of red bats in Indiana. He found that both Lepidoptera and Coleoptera were major components of the diet. Whitaker identified the fecal remains to taxonomic
Family, but his combined percentages for the Orders were equivalent to those found in this study. 15
CONCLUSIONS AND MANAGEMENT IMPLICATIONS
Previous authors have reported that the most important factors governing bat distribution are the availability of roosts, prey, and perhaps water. All of these habitat components can be found in most forested urban settings. While this study was limited in duration, my results suggest that urban forests in the intensively-farmed regions of the
Midwest may provide important habitat for foliage-roosting bats. Maintenance of mature shaded trees with dense canopies and open understories in these urban forests appears to be particularly important. Finally, wooded corridors in towns and residential areas provide protective roost sites in close proximity to foraging sites. These are particularly beneficial to red bats and many other wildlife species and should be maintained and/or established when possible. 16
LITERATURE CITED
Aldridge, H. D. J. N., and R. M. Brigham. 1988. Load carrying and maneuverability in an insectivorous bat: a test of the 5% "rule" of radio-telemetry. J. Mammal. 69:379- 382.
Anthony, E. L. 1988. Age determination in bats. Pages 47-58 in T.H Kunz, ed. Ecological and behavioral methods for the study of bats. Smithsonian Institution. Washington D.C.
Barbour, R. W. and W. H. Davis. 1969. Bats of America. Univ. Press of Kentucky, Lexington. 286pp.
Barclay, R. M., P.A. Faure, and D.R. Farr. 1988. Roosting behavior and roost selection by migrating silver-haired bats (Lasionycteris noctivagans). J. Mammal. 69:821-825.
Bradbury, J., D. Morrison, E. Stashko, and R. Heithaus. 1979. Radiotracking methods for bats. Bat Research News 20:9-17.
Campbell, L.A., J. G. Hallett, and M.A. O'Connell. 1996. Conservation of bats in managed forests: use ofroosts by Lasionycteris noctivagans. J. Mammal. 77:976-984.
Constantine, D. G. 1958. Ecological observations on lasiurine bats in Georgia. J. Mammal. 39:64-70.
__. 1966. Ecological observations on lasiurine bats in Iowa. J. Mammal. 47:34-41.
Dixon, K. R. and J. A. Chapman. 1980. Harmonic mean measure of animal activity areas. Ecology 61 : 1040-1044.
Downes, W. L. 1964. Unusual roosting behavior in red bats. J. Mammal. 45:143-14.
Eddy, W. F. 1977. A new convex hull algorithm for planar sets. ACM Transactions on Mathematical Software 3:398-403. 17
Fenton, M. B. and G. P. Bell. 1981. Recognition of species of insectivorous bats by their echolocation calls. J. Mammal. 62:233-243.
Findley, J. S. and D. E. Wilson. 1974. Observations on the neotropical disk-winged bat, Thyroptera tricolor. J. Mammal. 55:562-571.
Furlonger, C. L., H.J. Dewar, and M. B. Fenton. 1987. Habitat use by foraging insectivorous bats. Can. J. Zool. 65:284-288.
Hall, E. Rand K. R Kelson. 1959. The mammals ofNorthAmerica Vol. 1. Ronald Press, New York. 546 pp.
Hayward, G.D. and E. 0. Garton. 1984. Roost habitat selection by three small forest owls. Wilson Bull. 96:690-692.
Hill, J.E. and J. D. Smith. 1984. Bats: a natural history. Univ. of Texas Press, Austin. 243pp.
Hickey, M. B. 1992. Effects ofradiotransmitters on the attack success of hoary bats, Lasiurus cinereus. J. Mammal. 73 :344-346.
Hoffineister, D. 1989. Mammals oflllinois. Univ. oflllinois Press, Champaign. 348pp.
Jackson, H. H. 1961. The mammals ofWisconsin. Univ. ofWisconsinPress, Madison. 504pp.
Kunz, T. H .. 1973. Resource utilization: temporal and spatial components of bat activity in central Iowa. J. Mammal. 54:14-32.
__. 1982. Roosting ecology of bats. Pages 1-55 in T.H. Kunz, ed. Ecology of bats Plenum Press. New York. 425pp. 18
__ and A. Kurta. 1988. Capture methods and holding devices. Pages 1-30 in T.H Kunz, ed. Ecological and behavioral methods for the study of bats. Smithsonian Institution. Washington D.C.
__ and J. Whitaker. 1983. An evaluation of fecal analysis for determining food habits of insectivorous bats. Can. J. Zool. 61:1317-1321.
Kurta, A. and J. Teramino. 1992. Bat community structure in an urban park. Ecography 15:257-261.
_ _.. D. King, J. Teramino, J. Stnbley, and K. Wtlliams. 1993. Sunnner roosts of the endangered Indiana bat (Myotis soda/is) on the northern edge of its range. Am. Midi. Nat. 129:132-138.
Lewis, S. E. 1995. Roost fidelity of bats: a review. J. Mammal. 76:481-496.
McClure, H. E .. 1939. Red bats at Lewis, Iowa J. Mammal. 20:501-502.
__. 1942. Summer activities of bats (Genus Lasiurus) in Iowa. J. MammaJ. 23:430-434.
Morrison, D. W. 1978. Foraging ecology and energetics of the frugivorous bat Artibeus jamaicensis. Ecology 59:716-723.
__. 1980. Foraging and day-roosting dynamics of canopy fruit bats in Panama. J. Mammal. 61:20-29.
Salcedo, H. D. L. C., M. B. Fenton, M. B. Hickey, and R W. Blake. 1995. Energetic consequences of flight speeds of foraging red and hoary bats (Lasiurus borealis and Lasiurus cinereus; Chiroptera: Vespertilionidae). J. Exper. Biology 198:2245-2251.
Stuwe, M and C. Blohowiak. 1986. McPAAL Micro-computer programs for the analysis of animal locations. Smithsonian Institution, Washington D.C. 20 pp. 19
Walsberg, G. E. 1986. Thermal consequences of roost-site selection: the relative importance of three modes ofheat conservation. The Auk 103:1-7.
Whitaker, J. 0. 1972. Food habits of bats from Indiana. Can. J. Zool. 50:877-883.
___. 1988. Food habits analysis of insectivorous bats. Pages 171-190 in T. H. Kunz, ed. Ecological and behavioral methods for the study of bats. Smithsonian Institution. Washington D.C.
Wilson, N. 1965. Red bats attracted to insect light traps. J. Mammal. 46:704-705. 20
Table 1. Composition of tree species available for roosts, and species selected as roost sites in Charleston, IL. There was a significant influence of tree type on roost site selection (x.,2 =285.5; d.£=19).
Species Available Used N % N % Oaks (Quercus spp.) 57 27.8 31 36.0 Maples (Acer spp.) 49 23.9 15 17.0 Hickories (~ spp.) 34 16.6 13 15.0 Elms (1!lmus spp.) 16 7.8 1 1.0 Sweetgum (Liquidambar spp.) 1 0.5 17 19.0 Black Walnut (Juglans spp.) 0 0.0 5 6.0 Yellowwood (Cladrastis spp.) 0 0.0 3 3.0 Snags 8 3.9 Ash (Eraxinus spp.) 8 3.9 Dogwood (Comus spp.) 7 3.4 Ironwood (Ostrya spp.) 6 2.9 Hackberry (Celtis spp.) 4 2.0 Birch (Betula spp.) 3 1.5 Pines ~inus spp.) 3 1.5 Musclewood (Carpinus spp.) 3 1.5 Sycamores ~latanus spp.) 2 0.9 Black Cherry (Prunus spp.) 1 0.5 Cottonwood (Populus spp.) 1 0.5 Tulip (Liriodendron spp.) 1 0.5 Persimmon (Diospyros spp.) _1_ 0.5
Total 205 100.0 85 100.0 21
Table 2. Height (m) distribution ofroosts used by red bats.
Height Number Mean Height %
<5.0m 9 2.4 12.0 5 -10 41 6.3 54.7 10- 15 19 11.8 25.3 15 -20 5 17.2 6.7 >20m 1 21.4 1.3 Total 75 -- 100.0 22
Table 3. Distance (m) from the tree crown edge ofroost sites used by red bats.
Roost distance N % < 1.5 m 56 75 1.5 - 2.5 m 13 17 >2.5m 6 8
Total 75 100 23
Table 4. Distance (m) travelled between consecutive roosts by red bats.
Distance No. of movements Avg. Distance (m) % of movements <25m 28 3.5 46.0 25 < 50 5 38.9 8.2 50 < 75 7 62.2 11.5 75 < 100 1 77.6 1.6 100 < 150 6 122.l 9.8 150 < 200 3 181.9 4.9 200 <250 I 220.0 1.6 250 < 300 3 269.6 4.9 300 < 350 1 317.3 1.6 350 < 400 1 399.7 1.6 >400 5 555.5 8.2
Total 61 100.0 24
Table 5. Home range estimates (km2 ) for red bats equipped with radio-transmitters in Charleston, Illinois
Home Range Size (km2 ) Number Minimum Harmonic of Convex Mean Bat Locations Polygon Transformation Barney 9 0.30 0.16 Charlie 8 0.55 0.01 Diane 17 0.02 0.04 Ernie 5 6.29 0.01 Fred 19 0.07 0.21 George 4 0.06 0.03 Harriet 3 1.35 0.01 Izzy 3 0.02 0.01 Otis 9 0.10 0.24 Pat 13 0.17 0.10
Mean 9 0.89 0.08 25
Douglas-Hart Nature Center
;sumption
Hidden Springs State Forest
Figure 1. Location and vicinity maps of study sites sampled for red bats in central Illinois, May - September, 1996. 26
24%
6%
•Adult Male
12% •Adult Female
CJuvenile Male
•Juvenile Female
59%
Figure 2. Sex and age composition of red bats captured by mist-netting in Coles County Illinois, swnmer 1996. 27
7% 4% 10%
•Tree crowns •Grass CShlngles •Tree trunks
79%
Figure 3. Percentage ofroost types used by red bats in central Illinois, summer 1996. 28
40
DAvallable •Selected %
<15cm 15. 30 30.45 45-60 60-75 75 · 105 > 105 cm
Tree Diameter (dbh)
Figure 4.Diameter (dbh) distribution of trees available for roosting versus those actually used by red bats in Coles County Illinois, Summer 1996. There was a significant influence of d.b.h. on roost site selection ex: =164.9; d.f.=6).