Emergence and foraging behavior in small populations of Idaho bats [thesis]

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In summer and fall 1966, bats belonging to the general Myotis and Eptesicus were investigated at five roosts near Moscow, Idaho. The threshold of illumination at which bats of the genus Myotis began their foraging was shown to be 0.8 foot-candle or less. Eptesicus fuscus emerged at 1.6 foot-candles. The illumination at which bats of the genus Myotis emerged appeared to decrease slightly from August through September 1966. Temperature, relative humidity, and barometric pressure were found to play little or no role in determining the time of evening emergence. On the nights of highest temperature, the greatest number of bats were seen. All roosts were associated with high relative humidity and running or standing water. Foraging was intermittent on the part of individual bats. Bats foraged primarily in flyways immediately adjacent to the roosts. The flight of Myotis was very erratic. These bats flew from 10 to 25 feet high. Eptesicus flew more directly and at an altitude of 100 to 200 feet. Territoriality and investigative behavior appeared to be present. Collection of discarded insect wings beneath the roost revealed the use of Lepidoptera and Hymenoptera as food. Light sampling behavior was observed on two occasions in Myotis evotis. Similar behavior was induced well after foraging had begun by directing bright light sources on a mine entrance. Bats of different species were never seen to roost less than ten feet apart.

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ELECTRONIC FILE - Zoology: Mammals

Citation: Bonnell ML. 1967. Emergence and foraging behavior in small populations of Idaho bats [thesis]. Moscow (ID): University of Idaho. 64 pp.