Published on: Mar 3, 2016
Transcripts - NASBR_Poster
ROOST TREES OF SOUTHEASTERN MYOTIS AND RAFINESQUE’S BIG-EARED
BATS IN THE BOTTOMLANDS OF ARKANSAS
Samuel Schratz*, V. Rolland, T.S. Risch
Department of Biological Sciences, Arkansas State University, P.O. Box 599, State University, AR 72467.
Contact: email@example.com; Presenter*
The Cache River National Wildlife Refuge holds a large continuous tract
of bottomland hardwood forest in the Mississippi Alluvial Valley (MAV).
The southeastern myotis (Myotis austroriparius, MYAU) and
Rafinesque’s big-eared bat (Corynorhinus rafinesquii, CORA) of
Arkansas are assumed to be year-round residents of the MAV and
primarily roost in trees.
Although contact with White-Nose Syndrome is unlikely to impact MYAU
or CORA in Arkansas, loss of bottomland habitat remains a threat.
Identification of roost-tree characteristics will allow for more informed
forest management practices.
Bats were captured via mist-netting
in closed-canopy flyways and over
Affixed 0.31g (2014) and 0.27g
(2015) LB-2X Holohill transmitters
to 32 bats (Fig. 1) and located by
homing. Transmitters used in 2015
had a stronger signal output than
Located diurnal roosts and
characterized trees by measuring
diameter at breast height, canopy
coverage, basal area, and tree
Random trees were located by
generating a number from 0-360
(for directionality) and 40-100 (for
distance in meters).
Characterized random trees in
same manner as roost-trees.
Data analysis conducted in
1Medlin and Risch (2008). Habitat Associations of Bottomland Bats, with Focus on Rafinesque's Big-Eared Bat and Southeastern Myotis. American Midland
Naturalist, 160, 400-412.
2Mirowsky et al. (2013). Distributional Records and Roosts of Southeastern Myotis and Rafinesque's Big-Eared Bat in Eastern Texas. Southwestern Association of
Naturalist, 49, 294-298.
3Carver and Ashley (2007). Roost Tree Use by Sympatric Rafinesque's Big-eared Bats (Corynorhinus rafinesquii) and Southeastern Myotis (Myotis austroriparius).
American Midland Naturalist, 160, 364-373.
4Dahl, T. E. 1990. Wetlands: Losses in the United States 1780’s to 1980's.
Both MYAU and CORA show affinity towards larger trees with higher basal area than random trees, however
species differ in their preferences for tree height and canopy coverage.
CORA and MYAU select for similar tree characteristics (canopy coverage, basal area and tree height).
However, selection differs between species with tree diameter.
Inability to accurately measure DBH of trees with large swellings (buttresses) may make it hard to compare
results to other studies.
Characterize roost selection of southeastern myotis and Rafinesque’s
big-eared bat in Arkansas’ bottomlands.
A special thanks to my field techs, Elizabeth Rush, Megan Wallrichs, Adam Lee, NiKayla Hughes, Alex Gurley, and Megan Buckley for their invaluable field
assistance and thanks to Tracy Klotz, Phillip Jordan, Jimmy Gore, Patrick Moore and Daniel Istvanko for their assistance and guidance during my field seasons.
An additional thanks to U.S. Fish and Wildlife for funding my project.
Fig. 3 – Roost containing over 100
We located roosts of 12
MYAU (7♂,5♀), and 8 CORA
CORA selected for larger
diameter trees than MYAU
(p=0.049), but there were no
differences in canopy
coverage (p=0.74), basal area
(p=0.75), and height (p=0.17)
56% of roost trees had basal
openings, 20.5% had
chimney openings, 12.8%
had neither chimney nor
basal openings, 2.5% had
both chimney and basal
openings, 7.6% had window
Diameter at Breast Height
Fig. 2 – Rafinesque’s big-eared bat
with aluminum band
Fig. 1 – Southeastern myotis with transmitter
Abstract: Transmitters were affixed to 23 Myotis austroriparius (13 males; 10 females) and 9
Corynorhinus rafinesquii (5 males; 4 females). Bats were tracked daily to their roost trees for the
life of the transmitter. Roosts were discovered from 20 bats with some bats using multiple
roosts. Thirty roosts were located in water tupelos (Nyssa aquatica) with large basal hollows and
chimney openings, 5 were located in bald cypress (Taxodium distichum). All roost sites were in
living trees. Roost trees for both bat species were larger in diameter and in thicker stands than
trees selected at random.
Relevance to Conservation
As wind energy continues to negatively impact tree-roosting bats and WNS continues to cause decline in
caverniculous bats, knowledge and preservation of bottomland bat habitat is critical.
Arkansas has lost over 70% of its bottomland habitat since colonization.4
Protection and conservation of large roost trees in contiguous habitat is necessary to delay the declining
population trend of MYAU and CORA.
Fig. 4 – Wilcoxon Rank-signed tests of 4 variables between roost (gray) and
random trees (white) for CORA and MYAU, with α=0.05.
Table 1 – Roost trees by