Recognition: Slightly larger than the western pipistrelle, the eastern pipistrelle is readily distinguished by its tri-colored dorsal hairs, dark brown at tips and bases with a band of yellow between. Measurements include: total length, 70-90, forearm, 30-35, wingspan about 210; weight 5-8 g.
Distribution: This is a bat of eastern North America, ranging from Nova Scotia and Minnesota south to Mexico, Guatemala and Belize. There is a single Colorado record, from Greeley that is indicated as a yellow dot on the map on the previous page.
Habitat and Habits: The eastern pipistrelle is an animal of open deciduous forests. The animals are not strongly migratory, typically spending the summer in the same general region as the hibernaculum.
Breeding: Adults in reproductive condition have been captured in the southeastern U. S. in winter and spring. Twin births are the rule in late spring or early summer.
Food: Eastern pipistrelles emerge early, while still light, to forage in clearings or over still water for smaller insects, including moths, flies and beetles.
Remarks: The single record of this species in Colorado is of an animal captured from the side of a building in Greeley in September 1987. This locality is nearly 500 km from the previously documented range of the species in eastern Nebraska, north-central Kansas and the Texas Panhandle. Until information to the contrary develops, the conservative course is to consider it an accidental occurrence.
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