Pale Townsend's Big-Eared Bat - Illustration by George Maleski

Pale Townsend's Big-Eared Bat
Plecotus townsendii pallescens

 

P.t. pallescens can be distinguished from all other western bats by a two-pronged, glandular lump on the nostrils, and by large, rabbit-like ears.1 This species is a medium-sized bat with buffy brown dorsal fur and paler underparts.

Habitat: P.t. pallescens roosts in caves, lava tubes, and abandoned mines.2 Shelters in which the bats have been found range from the low, arid desert, to the fir zone in upper elevations.1 In winter, the bats hibernate in cold caves and mines in the upland and mountains from the Grand Canyon to the southeastern part of Arizona.2

Range: The historic range of P.t. pallescens includes Arizona, California, Colorado, Idaho, Kansas, Montana, North Dakota, Nebraska, New Mexico, Oklahoma, South Dakota, and Mexico. The distribution of the bat seems to be determined by the availability of caves or cave-like roosting habitat.1 The bat is widespread throughout Arizona, but not common anywhere and least common in the northeastern grasslands and the southwestern desert areas.2

Diet: P.t. pallescens feeds on insects, mainly moths. The bat is a "late flyer," emerging almost an hour after sunset.1 The bat feeds near forested areas, gleaning insects off plant leaves or in flight.

Reproduction: Mating occurs from October to February. The female stores the sperm until spring when fertilization occurs. Gestation length varies from 56­100 days.1 In Arizona, pregnant females congregate in maternity colonies, usually in warmer areas of the cave. The maternity colonies are formed in March or April. Most young are born in June and are weaned and flying by mid-July.2

Status: P.t. pallescens is a U.S. Fish and Wildlife Service "Species of Concern."1 P.t. pallescens is a relatively sedentary creature, and has demonstrated a high degree of site fidelity.1 The bat typically roosts in highly visible clusters near the mouth of the roost site. Habitat loss, vandalism, and disturbance by cave explorers can cause permanent abandonment of the site.1 Low reproductive potential, high longevity, and high roost fidelity make this species populations highly sensitive to roost threats.1

Pale Townsend's Big-Eared Bat in Pima County: The Baboquivari Mountains have one of the largest summer colonies of the Pale Townsend's Big-Eared Bat in Arizona.1 The bat is also found in Colossal Cave, Tucson Mountina Park, Organ Pipe National Monument, and Saguaro National Park. Because P.t. pallescens is extremely sensitive to human disturbance and has a low reproduction rate, it is a species that requires special protection.1

References:

1. New Mexico Game and Fish Department. 1997. BISON-M Taxonomy.

2. Arizona Game and Fish Department. 1998. "Plecotus townsendii pallescens." Heritage Data Management System.


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