Activity patterns of California leaf-nosed and other bats at wildlife water developments in the Sonoran Desert

Abstract

I studied bat use of 3 isolated water developments on the Cabeza Prieta National Wildlife Refuge in southwestern Arizona between May 1995 and August 1997. I recorded bat echolocation calls to measure overall activity, videotaped bat behavior and identified aquatic insects to determine whether bats were feeding or drinking, mist netted to assess visitation patterns with respect to season, sex, and reproductive condition for each of 4 species captured, studied movements of banded individuals, and monitored roosts of the California leaf-nosed bat (Macrotus californicus) in nearby mines. Echolocation activity was much higher at water than in nearby dry desert washes and was greater in dry washes than at random sites away from water. Bats visited water in all seasons, visiting primarily to drink, not to feed on insects. The California leaf-nosed bat constituted 41% of more than 1,000 captures. I concluded that in my study area this species made extensive use of water developments for drinking, particularly during lactation.