Southeastern Naturalist
B.B. Gregory, J.O. Whitaker, Jr., and G.D. Hartman
2014 Vol. 13, No. 4
762
2014 SOUTHEASTERN NATURALIST 13(4):762–769
Diet of Rafinesque’s Big-eared Bat (Corynorhinus
rafinesquii) in West-central Louisiana
Beau B. Gregory¹,*, John O. Whitaker, Jr.², and Gregory D. Hartman³
Abstract - We investigated the diet of Corynorhinus rafinesquii (Rafinesque’s Big-eared
Bat) in west-central Louisiana by examining fecal pellets collected from beneath 3 bridges
used by these bats as day roosts. Fresh fecal material was found under the bridges during
every month of the year. We detected 5 insect orders, including 5 families, in fecal pellets
collected from 25 August 2005 to 5 January 2007. Lepidoptera represented 93.7% of
the total volume and was the only order observed in 100% of our samples. Coleopterans,
mostly Scarabaeidae, were the second most abundant food item and represented 5.8% of
the total volume. Hemiptera, Diptera, and Hymenoptera together represented 0.4 % of the
total volume. We observed Diptera, Hemiptera, Hymenoptera, and Coleoptera in fecal pellets
collected under some, but not all bridges. No insect orders were observed that had not
previously been reported as prey of Rafinesque’s Big-eared Bats. Our results were similar
to those reported in studies conducted in Kentucky, North Carolina, and Florida, and we
concluded that Rafinesque’s Big-eared Bats primarily prey upon lepidopterans in Louisiana.
Introduction
Corynorhinus rafinesquii (Lesson) (Rafinesque’s Big-eared Bat) occurs in much
of the eastern US and is considered to be a moth specialist (Hurst and Lacki 1997,
Johnson and Lacki 2013, Lacki and Dodd 2010, Whitaker et al. 2007). This bat currently
is considered a species of concern in every state where it occurs (Bayless et
al. 2011). There are no published studies on the diet of these bats within the western
portion of their geographic range. Because life-history information can aid management
efforts, we report foods detected in feces of Rafinesque’s Big-eared Bats in
Louisiana, near the western extent of the species’ range.
Study Area
We conducted our study within a 500-km2 area of Vernon Parish in west-central
Louisiana within the boundaries of Fort Polk Military Reservation and neighboring
Vernon Unit of the Kisatchie National Forest, Leesville, LA (Fig. 1). The area
was characterized by gently rolling hills dominated by managed stands of Pinus
palustris Mill. (Longleaf Pine), Pinus taeda L. (Loblolly Pine), and Pinus elliottii
Engelm. (Slash Pine). Deciduous trees including Quercus spp. (oaks), Nyssa spp.
(black gums), and Taxodium distichum (L.) Rich. (Baldcypress) dominated riparian
areas (Carrie et al. 2002, Lance et al. 2001).
¹Coastal and Nongame Resources Division, Louisiana Department of Wildlife and Fisheries,
Baton Rouge, LA 70808. ²Department of Biology, Indiana State University, Terre Haute,
IN 47809. ³Department of Biology, Gordon State College, Barnesville, GA 30204. *Corresponding
author - bgregory@wlf.la.gov.
Manuscript Editor: Renn Tumlison
Southeastern Naturalist
763
B.B. Gregory, J.O. Whitaker, Jr., and G.D. Hartman
2014 Vol. 13, No. 4
We collected fecal pellets under 3 T-beam girder bridges hereafter referred to as
bridges I, II, and III. Bridges I and II were on paved roads and bridge III, a gravel
road. The distances between bridges I and II, I and III, and II and III were 12.5, 15,
and 5 km, respectively. Riparian habitats within a 0.25-km radius of bridges I and
II were undeveloped forest, and there was a wastewater treatment facility in a 10-ha
clearing ~0.1 km from bridge III.
Methods
From 25 August 2005 to 5 January 2007, we collected 39 samples of fecal pellets
from Big-eared Bats; 13 samples from under each of the 3 bridges. All months
of the year were represented by at least 1 sample from each of the 3 bridges; however,
samples corresponding to a given month were not always collected on the
same date. Months represented twice in our dataset were August 2005 and 2006
for bridges I and II, and September 2005 and 2006 for bridge III. The number of
Rafinesque’s Big-eared Bats present during sampling events was variable; ranges =
1–9, 0–26, and 0–23 bats for bridges I, II, and III, respectively.
Fecal pellets were collected with forceps, deposited in 7-ml glass vials, and
stored at room temperature until we analyzed the samples. We assumed that fecal
Figure 1. Location of study area.
Southeastern Naturalist
B.B. Gregory, J.O. Whitaker, Jr., and G.D. Hartman
2014 Vol. 13, No. 4
764
pellets adhered to the concrete roosting surface were the most fresh and collected
them first; pellets located on the ground directly below roost sites were
collected next. Eptesicus fuscus (Beauvois) (Big Brown Bat), Myotis
austroriparius (Rhoads) (Southeastern Myotis), and Perimyotis subflavus
(Cuvier) (Eastern Pipistrelle) also occurred at the roosts, which could complicate
collection of fecal material. However, fecal pellets of Rafinesque’s Big-eared
Bats typically are distinctively helical (Hurst and Lacki 1997), which made it possible
to distinguish Rafinesque’s Big-eared Bat pellets from those of other
species. All samples consisted of multiple fecal pellets. After we collected fecal
pellets, we cleared the roosting surface and substrate at the collection site of any
remaining feces and foreign debris to provide a clean surface for feces to accumulate
in the future. Because collection sites were sometimes flooded by the creeks
running under the bridges, use of fecal-pellet collection sheets was not practical.
Substrate under the bridges predominately was loose sandy soil, allowing collection
sites to be easily scraped clean using a piece of lumber.
We covered fecal pellets with ethanol in a Petri dish and examined them using
a 10–70-power zoom dissecting microscope (Olympus America, SZH, Melville,
NY). We identified food items to the lowest taxonomic level possible and visually
estimated the percent volume of each food item for each pellet. Insect remains had
been chewed into pieces and thoroughly mixed; thus, it was not possible to measure
their volume directly or by water displacement. Data were summarized as percent
volume (sum of volumes in individual pellets for each item/sum of total volume x
100; see Whitaker 1988), which indicates the relative amount of each type of prey
in a sample. Percent frequency was recorded as the percentage of samples in which
a given food occurred. There were many particles that we could not identify; these
were assumed to be in similar proportion to identified foods. All fecal pellet analysis
was conducted by J.O. Whitaker, Jr.
Results
We found fresh fecal pellets during every month sampling was conducted, but
they were more abundant during warmer months. We identified representatives of
5 orders of insects (Table 1). Lepidoptera occurred in 100% of the samples, represented
93.7% of the total volume, and was the only order detected in 19 of our 39
samples. The total volume attributable to Lepidoptera ranged from 88.9 to 99.2% in
the combined samples from each of the 3 roost sites (Table 1). Coleopterans were
the second most abundant food item and represented 5.7% of the total volume; the
families Scarabaeidae and Carabidae represented 4.0% and 0.5% of the total volume,
respectively. Hemiptera, Diptera, and Hymenoptera were found in 7 samples
and together they accounted for 0.4% of the total volume. A small portion (0.1%
total volume) of the material was unidentifiable insect remains.
Among the 39 samples from the 3 bridges, the total volume attributable to Coleoptera
ranged from 0.7 to 10.1%. We detected Coleoptera in 15 samples (43.6%),
with the family Scarabaeidae representing from 40 to 47% of the total volume of
3 samples. Scarabaeidae and Diptera were detected only in samples from bridges I
Southeastern Naturalist
765
B.B. Gregory, J.O. Whitaker, Jr., and G.D. Hartman
2014 Vol. 13, No. 4
and II, and we observed Hemiptera and Hymenoptera only in fecal pellets collected
at bridge II.
Discussion
In west-central Louisiana, Rafinesque’s Big-eared Bats primarily consume
lepidopterans. Our findings were similar to those reported in other studies
where fecal pellets were analyzed near the northern extent of the species’ range
in southeastern Kentucky (Hurst and Lacki 1997, Johnson and Lacki 2013) and
in the southeastern extent of the range in central Florida (Whitaker et al. 2007).
West-central Louisiana is near the southwestern edge of the known range of
Rafinesque’s Big-eared Bat. Our findings further support earlier observations
of a high percentage of moths in the diet of members of the genus Corynorhinus
(Clark 1991; Hurst and Lacki 1997; Lacki and Dodd 2010; Ober and Hayes 2008;
Sample and Whitmore 1993; Whitaker et al. 1977, 1981, 2007).
Dietary percentage volumes reported in our study and the Kentucky and
Florida investigations were similar (Table 2). However, though trace amounts
of Trichoptera were recorded by Hurst and Lacki (1997), and small amounts of
Trichoptera and Orthoptera were reported by Whitaker et al. (2007), we did not
observe trichopteran or orthopteran remains in any fecal pellets we analyzed.
Arachnids and vegetation also were present in the fecal pellets of Rafinesque’s
Big-eared Bats from Florida, but these taxa were not detected in fecal pellets
from Kentucky or Louisiana. Seasonal differences in sampling regime, regional
variation in prey availability, and differences in the numbers of fecal pellets
Table 1. Mean percentage volume and frequency of insects observed from fecal pellets of Rafinesque’s
Big-eared Bats collected throughout the year at 3 bridge roosts in Louisiana. Some of the columns
with values for volume in the table do not sum to exactly 100 percent due to rounding. All = All roosts
combined.
Bridge I Bridge II Bridge III All
Taxon Volume Freq. Volume Freq. Volume Freq. Volume Freq.
Lepidoptera 93.2 100.0 88.9 100.0 99.2 100.0 93.7 100.0
Coleoptera
Unknown Coleoptera 2.0 23.1 1.1 30.8 0.5 15.4 1.2 23.1
Scarabaeidae 4.2 15.4 7.9 23.1 0.0 0.0 4.0 12.8
Carabidae 0.2 7.7 1.2 7.7 0.2 7.7 0.5 7.7
Hemiptera
Unknown Hemiptera 0.0 0.0 0.5 15.4 0.0 0.0 0.2 5.1
Cercopidae 0.0 0.0 0.2 7.7 0.0 0.0 0.1 2.6
Diptera
Unknown Diptera 0.2 15.4 0.0 0.0 0.0 0.0 0.1 5.1
Tipulidae 0.0 0.0 0.2 2.6 0.0 0.0 0.1 0.9
Hymenoptera
Formicidae 0.0 0.0 0.1 2.6 0.0 0.0 0.03 0.9
Unidentified insect 0.2 7.7 0.0 0.00 0.2 7.7 0.1 5.1
Southeastern Naturalist
B.B. Gregory, J.O. Whitaker, Jr., and G.D. Hartman
2014 Vol. 13, No. 4
766
analyzed may account for some of the differences among the findings reported in
the 3 studies (Table 2).
We observed Diptera, Scarabaeidae, Hemiptera, and Hymenoptera in fecal
pellets from some but not all of our sampling sites. Hurst and Lacki (1997) reported
a similar pattern for Homoptera, Hemiptera, Hymenoptera, and Trichoptera.
The availability of moths (Dodd et al. 2008, Johnson and Lacki 2013) and other
Table 2. Comparison of percentage volume and frequency of insects observed from fecal pellets of
Rafinesque’s Big-eared Bats in Louisiana with results reported in Florida and Kentucky. Some of the
columns with values for volume do not sum to exactly 100 percent due to rounding. Blank cell = not
reported or not detected, * = this study, ** = Whitaker et al. 2007, *** = Hurst and Lacki 1997.
Louisiana* Florida** Kentucky***
Mean
Volume Freq. Volume Freq. Volume freq.A
Taxon
Lepidoptera 93.70 100.00 93.70 99.40 93.90 100.00
.
Coleoptera (5.70) (43.60) (1.30) UnknownB 5.10 83.55
Unknown Coleoptera 1.20 23.10 0.80 2.30
Scarabaeidae 4.00 12.80 0.40 0.80
Carabidae 0.50 7.70 0.08 0.10
Circulionidae 0.02 0.20
Hemiptera (0.20) (5.10) (0.09) (0.50) 0.10 11.70
Unknown HemipteraC 0.20 5.10 0.09 0.50
Hemiptera (formerly Homoptera) (0.10) (2.60) (0.28) (0.60) 0.38 28.10
Cercopidae 0.10 2.60
Cicadellidae 0.08 0.50
Cicadidae 0.20 0.10
Diptera (0.20) (7.70) (2.96) UnknownB 0.23 16.90
Unknown Diptera 0.10 5.10 0.70 2.00
Calliphoridae 2.20 5.50
Tipulidae 0.10 2.60 0.03 0.10
Chironomidae 0.03 0.01
Hymenoptera (0.03) (0.90) (0.10) (0.30) 0.10 7.50
Formicidae 0.03 0.90 0.03 0.10
Ichneumonidae 0.07 0.30
Trichoptera 0.2 0.50 Trace 2.88
Orthoptera (0.04) (0.30)
Gryllidae 0.04 0.30
Unidentified insect 0.10 5.10 0.80 2.10 0.23 13.38
Acarina Trace 0.20
Araneae 0.40 0.20
Vegetation 0.02 0.10
ATotal percentage frequency not reported, average of individual r oosts.
BCannot be calculated from data provided.
CMay include unidentifiable insects formerly included in the orde r Homoptera.
Southeastern Naturalist
767
B.B. Gregory, J.O. Whitaker, Jr., and G.D. Hartman
2014 Vol. 13, No. 4
arthropods can vary with habitat, and Rafinesque’s Big-eared Bats forage in more
than 1 type of habitat (Johnson and Lacki 2013). In our study, there appeared to be
differences in the diet of bats roosting at different bridges; however, our samples
were not all collected during the same day within a month, and we were unable to
determine if the availability of prey varied across time and space.
The remains of arthropods in the fecal pellets of bats usually can be identified
only to the level of order or family. Moth-wing culls found beneath roosts of members
of Corynorhinus have been used to identify lepidopteran prey of the bats at the
level of genus or species, and to estimate the sizes of the prey (Burford and Lacki
1998, Hurst and Lacki 1997, Lacki and LaDeur 2001, Sample and Whitmore 1993,
Whitaker et al. 2007). We encountered only 1 moth-wing cull during our study, and
were not able to identify the species.
In west-central Louisiana, at least some Rafinesque’s Big-eared Bats forage
year-round. Bats in the genus Corynorhinus possess a suite of characteristics that
allows them to be effective at gleaning (Lacki and Dodd 2010, and references
therein), they are, however, capable of capturing moths during flight (Lacki and
LaDeur 2001). Gleaning is a behavior that allows bats to forage later into the night
and during cooler weather than is possible for those that forage primarily by aerial
hawking (Barclay 1991, Swift 1998). We observed lesser amounts of guano at the
roosting sites during cooler months; a pattern that could have been caused by reduced
foraging activity or use of alternate roost sites during those times (Johnson
et al. 2012, Jones 1977). Some moths in the families Noctuidae and Geometridae
are known to fly during any month of the winter when air temperatures are at least
0 °C (Heinrich 1987, 1993), a behavioral capability that may result in reduced
predation pressure on the moths by bats and birds (Heinrich 1993). Moths in these
2 families commonly are consumed by Rafinesque’s Big-eared Bats (Johnson and
Lacki 2013).
Foraging activity of Rafinesque’s Big-eared Bats in Kentucky was positively associated
with distribution and availability of moths (Johnson and Lacki 2013), and
bats may consume individuals of some moth species disproportionately to the moth
species’ abundance (Lacki and LaDeur 2001). Because arthropod remains in fecal
pellets of bats usually can be identified only to order or family, it has been difficult
for researchers to rigorously test some hypotheses about the diet of Rafinesque’s
Big-eared and other bats. DNA recovered from bat feces has been used to successfully
identify prey items, often to the species level (Bohmann et al. 2011; Clare et
al. 2009, 2011; Dodd et al. 2012). Use of visual analyses coupled with DNA-based
techniques will help researchers better identify remains of prey items in fecal pellets,
and allow testing of hypotheses about diet of Rafinesque’s Big-eared Bats as it
relates to habitat, season, and the distribution and abundance of prey.
Because Rafinesque’s Big-eared Bat is considered a species of concern
throughout its range, it is important to obtain detailed knowledge of diet from
different geographic locations. More data are needed to understand diet in relation
to season, locality, and habitat type, and to know if any beneficial or pest
lepidopteran species of economic importance are being consumed. Forest and
Southeastern Naturalist
B.B. Gregory, J.O. Whitaker, Jr., and G.D. Hartman
2014 Vol. 13, No. 4
768
land-management practices potentially affect the suitability of a habitat for
roosting and foraging by bats (Hayes and Loeb 2007, Johnson and Lacki 2013).
Knowledge of the diet of Rafinesque’s Big-eared Bat at a finer taxonomic scale is
important for the development of land-management practices suitable to sustain
populations of these animals.
Acknowledgments
We thank the Conservation Branch at Fort Polk Military Reservation, Vernon Parish,
LA, for funding part of this study, and Fort Polk biologists for assistance in data collection.
M.J. Bender critically reviewed the manuscript and provided numerous suggestions that
helped to improve it.
Literature Cited
Barclay, R.M.R. 1991. Population structure of temperate zone insectivorous bats in relation
to foraging behavior and energy demand. Journal of Animal Ecology 60:165–178.
Bayless, M.L., M.K. Clark, R.C. Stark, B.S. Douglas, and S.M. Ginger. 2011. Distribution
and status of eastern big-eared bats (Corynorhinus spp.). Pp. 13−25, In S.C. Loeb, M.J.
Lacki, and D.A. Miller (Eds.). Conservation and Management of Eastern Big-eared
Bats: A Symposium. US Department of Agriculture, Forest Service, Southern Research
Station, Asheville, NC. General Technical Report SRS-145. 157 pp.
Bohmann, K., A. Monadjem, C.L. Noer, M. Rasmussen, M.R.K. Zeale, E. Clare, G. Jones,
E. Willerslev, and M.T.P. Gilbert. 2011. Molecular diet-analysis of two African freetailed
bats (Molossidae) using high throughput sequencing. PLoS ONE 6(6):e21441.
doi:10.1371/journal.pone.0021441
Burford, L.S., and M.J. Lacki. 1998. Moths consumed by Corynorhinus townsendii virginianus
in eastern Kentucky. American Midland Naturalist 139:141–146.
Carrie, N.R., R.O. Wagner, K.R. Moore, J.C. Sparks, E.L. Keith, and C.A. Melder. 2002.
Winter abundance of and habitat use by Henslow’s Sparrows in Louisiana. Wilson Bulletin
114:221–226.
Clare, E.L., E.E. Fraser, H.E. Braid, M.B. Fenton, and P.D.N. Hebert. 2009. Species on the
menu of a generalist predator, the Eastern Red Bat (Lasiurus borealis): Using a molecular
approach to detect arthropod prey. Molecular Ecology 18:2532–2542.
Clare, E.L., B.R. Barber, B.W. Sweeney, P.D.N. Hebert, and M.B. Fenton. 2011. Eating local:
Influences of habitat on the diet of Little Brown Bats (Myotis lucifugus). Molecular
Ecology 20:1772–1780.
Clark, M.K. 1991. Foraging ecology of Rafinesque’s Big-eared Bat, Plecotus rafinesquii,
in North Carolina. Bat Research News 32:68.
Dodd, L.E., M.J. Lacki, and L.K. Rieske. 2008. Variation in moth occurrence and implications
for foraging habitat in Ozark Big-eared Bats. Forest Ecology and Management
255:3866–3872.
Dodd, L.E., E.G. Chapman, J.D. Harwood, M.J. Lacki, and L.K. Rieske. 2012. Identification
of prey of Myotis septentrionalis using DNA-based techniques. Journal of Mammalogy
93:1119–1128.
Hayes, J.P., and S.C. Loeb. 2007. The influence of forest management on bats in North
America. Pp. 207–236 In M.J. Lacki, J.P. Hayes, and A. Kurta (Eds.). Bats in Forests:
Conservation and Management. Johns Hopkins University Press, Baltimore,
MD. 329 pp.
Southeastern Naturalist
769
B.B. Gregory, J.O. Whitaker, Jr., and G.D. Hartman
2014 Vol. 13, No. 4
Heinrich, B. 1987. Thermoregulation by winter-flying endothermic moths. The Journal of
Experimental Biology 127:313–332.
Heinrich, B. 1993. The Hot-blooded Insects: Strategies and Mechanisms of Thermoregulation.
Harvard University Press, Cambridge, MA. 607 pp.
Hurst, T.E., and M.J. Lacki. 1997. Food habits of Rafinesque’s Big-eared Bat in southeastern
Kentucky. Journal of Mammalogy 78:525–528.
Johnson, J.S., and M.J. Lacki. 2013. Habitat associations of Rafinesque’s Big-eared Bats
(Corynorhinus rafinesquii) and their lepidopteran prey in bottomland hardwood forests.
Canadian Journal of Zoology 91:94–101.
Johnson, J.S., M.J. Lacki, S.C. Thomas, and J.F. Grider. 2012. Frequent arousals from
winter torpor in Rafinesque’s Big-eared Bat (Corynorhinus rafinesquii). PLoS ONE
7(11):e49754. doi:10.1371/journal.pone.0049754.
Jones, C. 1977. Plecotus rafinesquii. Mammalian Species 69:1–4.
Lacki, M.J., and L.E. Dodd. 2010. Diet and foraging behavior of Corynorhinus in eastern
North America). Pp. 39−52, In S.C. Loeb, M.J. Lacki, and D.A. Miller (Eds.). Conservation
and Management of Eastern Big-eared Bats: A Symposium. US Department of
Agriculture, Forest Service, Southern Research Station, Asheville, NC. General Technical
Report SRS-145. 157 pp.
Lacki, M.J., and K.M. LaDeur. 2001. Seasonal use of lepidopteran prey by Rafinesque’s
Big-eared Bats (Corynorhinus rafinesquii). American Midland Naturalist 145:213–217.
Lance, R.F., B.T. Hardcastle, A. Talley, and P.L. Leberg. 2001. Day-roost selection by
Rafinesque’s Big-eared Bat (Corynorhinus rafinesquii) in Louisiana forests. Journal of
Mammalogy 82:166–172.
Ober, H.K., and J.P. Hayes. 2008. Prey selection by bats in forests of western Oregon. Journal
of Mammalogy 89:1191–1200.
Sample, B.E., and R.C. Whitmore. 1993. Food habits of the endangered Virginia Big-eared
Bat in West Virginia. Journal of Mammalogy 74:428–435.
Swift, S.M. 1998. Long-eared Bats. Cambridge University Press, Cambridge, UK. 182 pp.
Whitaker, J.O., Jr. 1988. Food-habits analysis of insectivorous bats. Pp. 171–189 In T.H.
Kunz (Ed.). Ecological and Behavioral Methods for the Study of Bats. Smithsonian Institution
Press, Washington, DC. 533 pp.
Whitaker, J.O., Jr., C. Maser, and L.E. Keller. 1977. Food habits of bats of western Oregon.
Northwest Science 51:46–55.
Whitaker, J.O., Jr., C. Maser, and S.P. Cross. 1981. Food habits of eastern Oregon bats,
based on stomach and scat analyses. Northwest Science 55:281–292.
Whitaker, J.O., Jr., M. Brooks, L. Scott, L.S. Finn, and C.L. Smith. 2007. Food habits of
Rafinesque’s Big-eared Bat from Florida. Florida Scientist 70:202–206.