Fluctuations in Bat-house Colony Size May Hamper Estimation of Population Changes
Robert M. R. Barclay1,*, Thiago A. Monteiro1, Erin N. Miller1, and Lara E. Hiles1
1Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1B4, Canada. *Corresponding author.
Journal of North American Bat Research, Special Issue 1 (2024): 1–10
Abstract
One method of assessing changes in bat population sizes is to count individuals emerging from roosts. Government agencies and conservation organizations use such counts. We conducted almost nightly counts at a Myotis lucifugus (Little Brown Bat) maternity colony in Calgary, Alberta, as well as 2–3 counts per week at another Little Brown Bat maternity colony in the Rocky Mountains west of Calgary. In both cases, the number of bats fluctuated widely from night to night, especially before parturition had occurred (Calgary colony, 8–154 bats; Rocky Mountains colony, 161–681 bats). After the start of parturitions, fluctuations were smaller, but still considerable (Calgary, 59–152 bats; Rocky Mountains, 197–464). This suggests that single, or even several, emergence counts conducted annually, as is often recommended, may not accurately document changes in colony size from year to year.
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Journal of North American Bat Research is valued by the academic, agency, NGO, and private-sector research community as a respected and trusted source for science related to all aspects of the biology, ecology, and conservation of bats, Order Chiroptera, and their habitats in North America, from Canada to Panama, and the West Indies (Bahamas, Greater Antilles, and Lesser Antilles). Manuscripts based on studies outside this region that provide information on species within the region may be considered at the Editor’s discretion.