Estimating sample size for landscape-scale mark-recapture studies of North American migratory tree bats

Acta Chiropterologica
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Abstract

Concern for migratory tree-roosting bats in North America has grown because of possible population declines from wind energy development. This concern has driven interest in estimating population-level changes. Mark-recapture methodology is one possible analytical framework for assessing bat population changes, but sample size requirements to produce reliable estimates have not been estimated. To illustrate the sample sizes necessary for a mark-recapture-based monitoring program we conducted power analyses using a statistical model that allows reencounters of live and dead marked individuals. We ran 1,000 simulations for each of five broad sample size categories in a Burnham joint model, and then compared the proportion of simulations in which 95% confidence intervals overlapped between and among years for a 4-year study. Additionally, we conducted sensitivity analyses of sample size to various capture probabilities and recovery probabilities. More than 50,000 individuals per year would need to be captured and released to accurately determine 10% and 15% declines in annual survival. To detect more dramatic declines of 33% or 50% survival over four years, then sample sizes of 25,000 or 10,000 per year, respectively, would be sufficient. Sensitivity analyses reveal that increasing recovery of dead marked individuals may be more valuable than increasing capture probability of marked individuals. Because of the extraordinary effort that would be required, we advise caution should such a mark-recapture effort be initiated because of the difficulty in attaining reliable estimates. We make recommendations for what techniques show the most promise for mark-recapture studies of bats because some techniques violate the assumptions of mark-recapture methodology when used to mark bats.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Estimating sample size for landscape-scale mark-recapture studies of North American migratory tree bats
Series title Acta Chiropterologica
DOI 10.3161/150811014X683426
Volume 16
Issue 1
Year Published 2014
Language English
Publisher Museum and Institute of Zoology, Polish Academy of Sciences
Contributing office(s) Fort Collins Science Center
Description 9 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Acta Chiropterologica
First page 231
Last page 239
Other Geospatial North America