Utilization of cave swallow nests by the cave myotis, Myotis velifer, in central Texas

Utilization of cave swallow nests by the cave Myotis, Myotis velifer, in central Texas. Print Title Annotation: GENERAL NOTES Author: Ritzi, Christopher M.; Walker, Christopher W.; Honeycutt, Rodney L. Geographic Code:1U7TX Date: May 1, 1998 Words: 591 Publication: The Texas Journal of Science ISSN: 0040-4403 It is known that Myotis velifer utilize the nests of cliff swallows, Petrochelidon pyrrhonota (cf. Buchanan 1958) and occasionally barn swallows, Hirundo rustica (cf. Jackson et al. 1982). However, there has been no record of this bat species using cave swallow, Petrochelidon fulva, nests as roosting sites. Buchanan (1958) attributed the use of cliff swallow nests by M. velifer to be prompted by a decrease in air temperature, especially when air mass direction was from the northwest. Recent studies of M. velifer roosting habits (Pitts & Scharninghausen 1986) suggest utilization of swallow nests by this species all year, except when temperatures are below freezing. This observation by Pitts & Scharninghausen is contrary to the previous explanation provided by Buchanan (1958). In December 1995, several specimens of Myotis velifer were found occupying two types of swallow nests (cliff and cave) located 5.1 miles N of Georgetown in Williamson County, Texas. These nestdwelling bats were discovered inside several boxed culverts along Interstate 35. This is the first record of M. velifer using cave swallow nests. Nests of cave swallows are similar to those of barn swallows, being cup-shaped but having a heavy protruding lip with higher sides. The higher sides and heavier lip associated with the cave swallow nest may provide protection against the wind currents that traverse the underground culverts, thus stabilizing the micro-environment around the bat. Not all observed nests were structurally identical and considerable variation in terms of bat occupancy was observed even when multiple nests were only a few feet apart. In many cases, two to three bats were found in a single nest. Observations also revealed that all nests were occupied by male bats. This sex bias may be seasonal in that more males were found in the culverts at this time. Extensive surveys of bats occupying similar box culverts along Interstate 45 in Leon and Madison counties, Texas, revealed several nests of barn, cave, and cliff swallows. Although M. velifer was not observed in these culverts, two other vespertilionid bats (Pipistrellus subflavus and Myotis austroriparius) were common (Walker et al. 1996). During the entire time that these two species were being studied, there was no record of either species utilizing swallow nests. From these observations, it appears that unlike these two species, M. velifer demonstrates a preference for swallow nests when roosting in culverts. Therefore, the use of swallow nests by M. velifer may provide a means of controlling micro-environment requirements not important to the other two species. ACKNOWLEDGMENTS We would like to thank Dr. Keith Arnold for identifying the swallow nests. Thanks also go to Jody K. Sandel for helping the senior author become familiar with bat culvert studies in the field. LITERATURE CITED Buchanan, O. M. 1958. Tadarida and Myotis occupying cliff swallow nests. J. Mammal., 39:434-435. Jackson, J. A., B. J. Schardien, D. Cooly & B. E. Rowe. 1982. Cave Myotis Roosting in Barn Swallow Nests. Southwest. Nat., 27(4): 463-464. Pitts, R. M. & J. J. Scharninghausen. 1986. Use of Cliff Swallow and Barn Swallow Nests by the Cave Bat, Myotis velifer, and the Free-tailed Bat, Tadarida brasiliensis. Texas J. Sci., 38(3): 265-266. Walker, C. W., J. K. Sandel, R. L. Honeycutt & C. Adams. 1996. Winter Utilization of Box Culverts by Vespertilionid Bats in Southeast Texas. Texas J. Sci., 48(2):166-168. Christopher M. Ritzi*, Christopher W. Walker and Rodney L. Honeycutt Department of Wildlife and Fishery Sciences Texas A & M University, College Station, Texas 77840 *Present address: Department of Biology, Sul Ross State University Alpine, Texas 79832 CMR at: [email protected] COPYRIGHT 1998 Texas Academy of Science Copyright 1998 Gale, Cengage Learning. All rights reserved.