Habitat use by spotted bats (Euderma maculatum, Chiroptera: Vespertilionidae): roosting and foraging behaviour

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Abstract
The purpose of this study was to collect data on the foraging and roosting behaviour of Euderma maculatum in the Okanagan Valley of southern British Columbia. The work was performed in the summer of 1981. Bats concentrated their foraging activity in open areas adjacent to ponderosa pine. None of the over 1000 attempted captures of prey we witnessed involved E. maculatum gleaning insects from ground or foliage, and we question the idea that big-eared bats are gleaners. Some attacks on flying insects involve steep dives to the ground, presumably in response to the defensive behaviour of prey. Spotted bats foraged alone, avoiding one another apparently by listening to the echolocation calls of conspecifics. Intrusion by one bat into the feeding area of another resulted in an altercation which stopped when one bat left the area. Heavy rain may have inhibited foraging flights, but there was no evidence that other meteorological factors or moonlight significantly inhibited foraging activity. The bats roosted alone in steep cliff faces and two radio-tagged individuals returned consistently to the same cliff face to roost. Departure was presumably influenced by light levels, as bats departed earlier on cloudy nights than on bright ones.