Use of abandoned mines by a community of temperate bats in Durango, Mexico

The Guanaceví region has been actively mined at least for the last 500 years. Mining activity has resulted in a large number of abandoned mines, which may represent important refuges for the chiropteran fauna of the region. I surveyed a sample of 25 abandoned mines during an annual cycle to determine which species use the mines, how they use it, and whether occupation is significantly related to a set of environmental variables measured from the mines. Simultaneously I carried out an inventory of the chiropteran fauna in the area, to determine what portion of the assemblage use the mines. I recorded 13 species for the region (12 vespertilionids and 1 molossid), out of 18 that are likely to occur. Five species were never found in mines; the remaining use them as feeding roosts, temporary roosts, or hibernacula, and only Corynorhinus mexicanus was found forming a maternity colony. Bats were significantly (P < 0.05) more frequent in mines with winter temperature < 10°C, adits > 50 m, and less than 3°C temperature oscillation throughout the year. Results suggest that bats are more likely to occur in undisturbed mines, although the relationship was not significant (P = 0.09).