Vesper Bat - Characteristics

Characteristics

Almost all vesper bats are insectivores, exceptions being some Myotis and Pizonyx species that catch fish and the larger Nyctalus species that have been known on occasion to catch small passerine birds in flight. The dental formula of vesper bats varies between species:

They rely mainly on echolocation, but they lack the enlarged noses some microbats have to improve the ultrasound beam, and instead "shout" through their open mouths to project their ultrasound beams. In compensation, many species have relatively large ears.

As a group, vesper bats cover the full gamut of flight ability, with the relatively weak-flying Pipistrellus that have fluttery, almost insect-like flight to the long-winged and fast-flying genera such as Lasiurus and Nyctalus. The family size range is from 3 to 13 cm (1.2 to 5.1 in) in length, excluding the tail, which is itself quite long in most species. They are generally brown or grey in color, but some have brightly colored fur, with reds, oranges, and yellows all being known, and many having white patches or stripes.

Most species roost in caves, although some make use of hollow trees, rocky crevices, animal burrows, or other forms of shelter. Colony sizes also vary greatly, with some roosting alone, and others in groups up to a million individuals. Species native to temperate latitudes typically hibernate, while a few of the tropical species aestivate.