BAT RESEARCH NEWS Volume 55: Number 2
Summer 2014
Sasse, D.B., and D.A. Saugey. 2014. Protection of water wells used as winter roosts by Rafinesque’s big-eared bats. Bat Research News, 55(2): 17–20.
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Protection of Water Wells Used as Winter Roosts by Rafinesque’s Big-eared Bats D. Blake Sasse1 and David A. Saugey2 1
Arkansas Game and Fish Commission, 213A Highway 89 South, Mayflower, AR 72106 and 2 Nightwing Consulting, P.O. Box 52, Jessieville, AR 71949 Email:
[email protected]
Old, large-diameter water wells have been known as winter roosting sites for Rafinesque’s big-eared bats (Corynorhinus rafinesquii) since the 1930s (Blair, 1939). Open wells, however, pose a safety hazard to humans and animals, which could accidentally fall into wells without adequate protective covers. Beginning in the late 1980s, biologists constructed well covers using tin or wooden grids that allowed access for bats, but these materials deteriorated over time (Sasse et al., 2011). In this paper, we describe installation of a new type of cover made from steel that appears to be well tolerated by the bats. Steel tops were placed on seven wells (Table 1) in southwestern Arkansas in September–December of 2008–2012 (Fig. 1). Covers were constructed from 3.2-mm-thick steel strap and 6.4-mm-thick steel plate and ranged in size from 79 to 127 cm2. Covers included access hatches (61–76 cm2) that allowed for researchers to observe bats and made it possible for landowners to draw water from these sites if necessary. The steel tops were secured to the sides of each well with four T-shaped legs that locked into sliding channels on the underside of the cover to allow for proper fit to the well. To maintain access for the bats, a gap of 7–11 cm was left between the top of the casing and the underside of the cover, although damage to one well (Willisville 1) resulted in a gap of 23 cm on one side. Counts of bats were performed multiple times, between October and March, at each site following installation. Bats continued to use all wells following construction and the
number of bats was equal to or higher than recent and/or historic counts with few exceptions (Table 1). Known historic summer roosts linked to the Stagecoach and Oak Grove Church wells were destroyed prior to 2004, perhaps accounting for lower population counts since 2004. In addition, the casing of Willisville 1 was destroyed during timber management operations on 11 November 2013; bats flew out of the well immediately after this occurred, and other bats may have been injured or killed by debris falling into the well, thus accounting for the apparent decrease in bats observed the following year. Use of steel covers apparently keeps these sites available for use as roosts for bats and a source of water for people, while removing human safety concerns. Funding for construction and installation was provided by Bat Conservation International and the Arkansas Game and Fish Commission. G. Humphreys of Deltic Timber assisted in installation of several covers. We thank Deltic Timber and other landowners for authorization to conduct this project on their property. Literature Cited Blair, W.F. 1939. Faunal relationships and geographic distribution of mammals in Oklahoma. American Midland Naturalist, 22:85–133. Sasse, D.B., D.A. Saugey, and D.R. England 2011. Winter roosting behavior of Rafinesque’s big-eared bats in southwestern Arkansas. Pp. 123–128, in Conservation and management of eastern big-eared bats: a symposium (S.C. Loeb,
© 2014 Bat Research News. All rights reserved.
18
Bat Research News
Volume 55: No. 2
B
A
C
D
E Figure 1. A) Typical uncovered well. B) Well cover showing hatch. C) Channel for leg. D) Leg. E) Well with installed cover.
9 5 32 60 33 -
Willisville 2
Oak Grove Church
Stagecoach
Sullivan
Brushy Branch
Mt. Holly
Pre-2004
Willisville 1
Name of well
-
-
1
6
2
1
2
2004
-
-
-
65
5
-
-
2005
-
-
-
15
-
-
-
2006
-
2
2
-
-
0
0
2007
-
-
15
-
9
-
-
2008
-
0
7
5
18
5
9
2009
Maximum number of bats
-
1
1
6
13
2
2
2010
-
2
1
42
11
0
1
2011
1
12
16
13
19
0
7
2012
1
13
20
3
25
1
12
2013
4
22
31
4
11
3
1
2014
Table 1. Maximum winter counts of bats at wells in southern Arkansas, before and after (indicated by bold) installation of steel covers.
Summer 2014 Bat Research News 19
20
Bat Research News M.J. Lacki, and D.A. Millers, eds.). General Technical Report SRS-145. U.S. Department of Agriculture, Forest
Volume 55: No. 2
Service, Southern Research Asheville, North Carolina.
Station,
