Bat Population Status in the U.S. and Territories

Research Task: 83279SW.8.0
Task Manager: Tom O'Shea

Bats are inconspicuous but important components of ecosystems, and are among the most diverse group of mammals. However, they have low reproduction rates, long generation times, and some species occur in limited numbers of aggregations and/or have very narrow physiological requirements for roost sites. Populations are consequently very susceptible to elevated mortality or depressed recruitment, and it is generally believed that bat populations have declined in the United States. Contaminants, disturbance to roosts, vandalism, and habitat change are among the factors contributing to declines. Several species are listed as endangered or threatened, and 25 additional species were considered Species of Concern by the U.S. Fish and Wildlife Service. Considering that some 43 species of bats occur in the United States, this is a significant proportion of bat species at risk. To develop a basis for analyzing trends in various populations and species of bats nationwide, USGS biologists compiled a database (http://www.fort.usgs.gov/products/data/bpd/bpd.asp) on historical counts of bats at colonies throughout the U.S. and Trust Territories. Working with partners at the National Fish and Wildlife Foundation, Bat Conservation International, Colorado State University, and others, FORT scientists convened a national workshop involving bat specialists and experts in sampling and analysis of wildlife populations to evaluate the current status of bat populations and the methods used to estimate their trends. Findings from the workshop were subsequently published in a peer-reviewed special publication, Monitoring Trends in Bat Populations of the United States and Territories: Problems and Prospects (available online at http://www.fort.usgs.gov/products/publications/21329/21329.asp). This document synthesizes all available data pertinent to its title (including an analysis based on the USGS database), evaluates the strengths and weaknesses of past and current methods for monitoring bat populations, and recommends new approaches for monitoring bat populations in the future.

 For more information contact Tom O'Shea

Related Products

Publications

• Colorado bat conservation plan
• Monitoring trends in bat populations of the United States and territories: problems and prospects
• Monitoring trends in bat populations of the United States and territories: status of the science and recommendations for the future