Distribution, Status, and Management of Townsends Big-eared Bat (Corynorhinus townsendii) in California
Pierson ED and Rainey WE. 1998. Distribution, Status, and Management of Townsends Big-eared Bat (Corynorhinus townsendii) in California. BMCP Technical Report Number 96-7
"A four year survey (1987-1991) investigating the status of Townsend’s big-eared bat,Corynorhinus townsendii, in California shows marked population declines over the past 40 years: a 52% loss in the number of maternity colonies, a 44% decline in the number of available roosts, a 55% decline in the total number of animals (primarily adult females), and a 32% decrease in the average size of remaining colonies. The data indicate that C. townsendii is roost limited, and the primary cause for the observed declines has been human disturbance of roosting sites. The 37 known colonies have a total population of approximately 4,250 adult females. Only three of these colonies have adequately protected roost sites. Declines are also indicated at four important hibernating sites for which past population data are available."