Townsend's Big-eared Bat

Townsend's big-eared bat being weighed and measured

Townsend's big-eared bat (Corynorhinus townsendii), is blue listed (at risk) in British Columbia. A nursing female will consume her weight in insects each night, which is equivalent to an adult human eating 230 hamburgers in 6-8 hours!


Biodiversity Interactive Map - Townsend's Big-eared Bat


  • From southern Mexico through the western United States into southern British Columbia.
  • Populations occur throughout the Columbia Basin (Cranbrook, Creston, Castlegar, Trail, Slocan Valley)


  • Occurs in a wide variety of habitats (upland, wetland, dryland and riparian) primarily at low elevations
  • Prefers relatively cold places with stable temperatures throughout winter for hibernation.
  • Maternity roosts found in caves and anthropogenic structures


  • Mating occurs in November through February in the hibernacula.
  • Females form maternity colonies of a dozen to several hundred, and give birth to their single young after gestation of 50-100 days.  Delayed implantation of the fertilized egg in the wall of the uterus can increase this gestation period so that births occur at a time when survival of the young is most likely.
  • They form tightly packed clusters in order to reduce heat loss and thus promote rapid development of the young.

Listing and Date

Listing Date
B.C. List Blue 2000
SARA S3 2006

Threats to Species

  • Loss of foraging and roosting habitat through land development (agriculture, reservoir creation, mine deactivation)
  • Disturbance at maternity roosts and hibernation sites

Select Reports

Full Report Listing (most recent on top)

For more information on this species, visit The BC Species and Ecosystem Explorer and enter "Townsend's big-eared bat" in the Species Name field.




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