RANGE:

A map of the state-by-state distribution of this species showing maternity sites, hibernacula, mist-net capture sites and museum voucher specimen sites was prepared in 1995 and is referenced below. This bat is found in British Columbia, east through Montana, south into western south Dakota, Nebraska, Kansas, Oklahoma and Texas, south into Mexico and along the Pacific Coastal States of California, Oregon, and Washington. In Idaho, it has been collected or observed in hibernal sites in 17 counties. Four maternity sites have been found in Boundary, Bonner, and Butte Counties. Many abandoned mine sites, often extremely dangerous to enter, are used by nonbreeding females and males for roosting in summer.

DESCRIPTION:

The dorsal fur is brownish to grayish brown. The ears, which may be curled like ram horns during torpor and hibernation, are brown and long (30-39mm); the tragus is about one-half the length of the ear. Glandular lumps occur on the face between the nostrils and eyes.

HABITAT:

Townsend's bats occur in a variety of habitats from desert shrub to deciduous and coniferous forests at a wide range of elevations. In Idaho, some individuals likely migrate to hibernal sites to overwinter and disperse to forested areas during summer when the sexes separate. Other individuals found near Lake Pend Oreille seem use the same mine during both summer and winter. This species is captured or observed in abandoned mines and both unoccupied and actively used old buildings where it may be considered a pest as a result of deposition of guano and urine. In California, two radiotagged females have been relocated in tree cavities where they remained for several days. It is probable that hollow cavities in large trees or snags may constitute an important undocumented resource for maternity colonies of this species, a condition that may be displacing some nursery colonies to man-made structures.

DIET:

C. townsendii are moth specialists. Their diet consists mostly of moths in the family Noctuidae. Beetles and flies and lesser amounts of other insects may also be consumed.

ECOLOGY:

The winter ecology and summer distribution of this species is under intensive investigation in Idaho as a result of concern about declining numbers observed at winter hibernal sites. Mines and caves that have been surveyed by netting during summers usually yield from one to six individuals. In northern Idaho, winter hibernal sites contain fewer than a dozen individuals. The largest maternity colony, containing a total of 50 females and pups, occurs in a actively used outbuilding in Bonner County. Thermal profiles for this structure suggest pups are delivered in cooler conditions that documented in other states. In southern Idaho, several lava tube caves exist that contained from 150 to 400 overwintering individuals. The larger population has declined significantly, but it is unclear whether the decline resulted through human induced mortality as a result of disturbance, displacement, or as a result of a natural tendency for this species to shift site locations.

REPRODUCTION:

Mating takes place during the fall, and ovulation and implantation in spring. A single pup is produced by each female in June in northern Idaho. Maternity colonies may require warmer temperatures to speed pup development, but more research is needed on the variation in temperatures required for successful rearing and recruitment throughout the range of this species.

IMPORTANT STATE REFERENCES:

Pierson, E.D., M.C. Wackenhut, J.S. Autenbach, P. Bradley, P. Call, D.L. Genter, C.E. Harris, B.L. Keller, B. Lengus, L. Lewis, B. Luce, K.W. Navo, J.M. Perkins, S. Smith, and L. Welch. 1999. Species conservation assessment and strategy for Townsend's big-eared bat (Corynorhinus townsendii townsendii and Corynorhinus townsendii pallescens). Idaho Conservation Effort, Idaho Department of Fish and Game, Boise, Idaho. 42pp.+ appendices. Available from P.O. Box 25, Boise, ID 83707-0025.

Keller, B.L. 1997. An analysis of bat occupancy of selected inactive mines located adjacent to the shore of Lake Pend Oreille, Bonner county and the Bethlehem and Montgomery mine,

Boundary County, Idaho. Unpublished Challenge Cost-Share Report, Idaho Panhandle National Forests and National Fish and Wildlife Foundation. 19pp.+ appendices.

Keller, B.L. 2000. Assessment of inactive mines as bat habitat in northern Idaho: Summary of BLM research 1994-99. Technical

Bulletin No. 00-01, Idaho Bureau of Land Management. 92pp.

IMPORTANT GENERAL REFERENCE:

Kunz, T.H. and R.A. Martin. 1982. Plecotus townsendii. American Society of Mammalogists, Mammalian Species, 175:1-6.