Animal Sciences Commons^™

Raptors Present But Unobserved: Detectability At A Western Migration Watch-Site And Its Effect On Trend Analysis, Eric G. Nolte

Boise State University Theses and Dissertations

Annual counts of migrating raptors (Accipitriformes, Falconiformes) are used as indices of population size. Variation in the proportion of the raptor population counted may decrease precision of trend estimates, thereby reducing power of inference. The proportion counted is the product of sample coverage and probability of detection. It is possible to improve the power of trend analysis by the adoption of techniques, such as double-observer or distance sampling, which estimate the probability of detection. I used a dependent double-observer method to estimate detectability at the annual fall raptor migration count at Lucky Peak, Idaho, in 2009 and 2010. …