Pallid Bat (Antrozous pallidus)

Photograph of the Pallid Bat


Protection Status Notes
A. pallidus is not listed by the U.S. Fish and Wildlife Service. It has undergone a major decline in some areas, especially in coastal California, however, its status and population trends in Texas are unknown.
Antrozous pallidus is a large (forearm 48‑60 mm), pale bat with large ears, blunt snout (with ridge across the top), and a distinctive skunk‑like odor.
Life History
Pallid bats are gregarious, and often roost in colonies of between 20 and several hundred individuals. Pregnant females gather in summer maternity colonies within warm rock crevices, abandoned mines, caves, hollow trees and in cavern‑like building features (e.g. attics). Copulation takes place between October and February, with parturition generally occurring between May and July depending on local climatic variables. Females can give birth to a single pup, twins and sometimes triplets, with twins being most common. Young are generally weaned in mid to late August. Maternity colonies disband between August and October. The bats are relatively inactive during the winter. They are not known to migrate, and are believed to hibernate as solitary individuals or in small numbers. Occasional winter activity has been reported in southern portions of its range.

Pallid bats roost in rock crevices, tree hollows, mines, caves, and a variety of anthropogenic structures, including vacant and occupied buildings. Tree roosting has been documented in large conifer snags (e.g. ponderosa pine), inside basal hollows of redwoods and giant sequoias, and bole cavities in oaks. They have also been reported roosting in stacks of burlap sacks and stone piles.

They are primarily insectivorous, feeding on large prey that are taken on the ground, or sometimes in flight. Prey items also include flightless arthropods such as scorpions, ground crickets, and cicadas.
A. pallidus is distributed from southern British Columbia and Montana to central Mexico, and east to Texas, Oklahoma and Kansas. An isolated population also occurs on Cuba. A. pallidus occurs in a number of habitats ranging form rocky arid deserts to grasslands into higher elevation coniferous forests. They are most abundant in the arid Sonoran life zones below 6,000 feet, but have been found up to 10,000 feet in the Sierra Nevada.

The pallid bat is a common resident of the western one-half of Texas where two distinct races are known: A. p. bunkeri in the northern Panhandle and A. p. pallidus in the west and south.
Threats and Reasons for Decline
Use of mines places this species in jeopardy with regards to mine closure projects. Additional threats include human vandalism within roost sites, roost site destruction, extermination in buildings and pesticide use. Loss of tree roosts could occur through commercial timber harvest (including selective hardwood removal), and loss of oaks to suburban expansion, and/or vineyard development.
Ongoing Recovery
Pallid bats consume large numbers of a wide variety of crop pests, and in areas where they are still abundant, must have substantial economic, as well as ecological impact. Since pallid bats often live in buildings, human harassment and needless killing rank among their greatest threats. Those that cause a nuisance by night roosting in open porches often can be persuaded to leave for several months at a time by spraying roosting surfaces with squirrel or dog repellent. They can be excluded from day-roosting in buildings, though their small colonies do not often cause substantial nuisances and may, in many cases, be worth tolerating.
Data is lacking regarding seasonal movements (it is currently believed that they do not migrate long distances between summer and wintering sites). Additional information is required regarding winter activity patterns (i.e. roost sites, activity levels etc.). More information is needed on roosting requirements in natural roosts (e.g. rock crevices and tree hollows).
For more information

Additional details can be found in the online version of The Mammals of Texas for the Pallid Bat