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Evaluation of current population indices for band-tailed pigeons

Michael L. Casazza·Julie L. Yee·Michael R. Miller·Dennis L. Orthmeyer·Daniel R. Yparraguirre·Robert L. Jarvis·Cory T. Overton
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Abstract

There is no formal population survey specifically designed to index population abundance of band-tailed pigeons ( Patagioenas fasciata ) throughout their range. Data from the Breeding Bird Survey (BBS), Washington and Oregon Mineral-Site (WAORMS) surveys, and Washington Call Count (WACC) survey offer evidence of long-term population decline. We investigated the potential to augment BBS, WACC, and WAORMS surveys to provide more precise population indices for the Pacific Coast band-tailed pigeon ( P. f. monilis ) and augment the BBS to index the Interior or “Four Corners” population ( P. f. fasciata ). We calculated statistical power, the probability of detecting population change given that a change exists, and analyzed survey data to investigate the effect of route length, survey repetition, and sample size. Sample sizes of 50 sites or routes yielded corresponding powers of 99% for WAORMS, 54% for WACC, and 30% for Pacific BBS, to detect a 10% annual change over a 5-year period (a = 0.10). Route length and repetition of surveys had little impact on power. Mineral-site surveys provide the greatest potential to monitor breeding populations and detect short-term trends in the Pacific Coast population. New survey techniques are needed for the Interior band-tailed pigeon.

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Michael L. Casazza, Julie L. Yee, Michael R. Miller, Dennis L. Orthmeyer, Daniel R. Yparraguirre, Robert L. Jarvis, Cory T. Overton. 2005. Evaluation of current population indices for band-tailed pigeons. https://doi.org/10.2193/0091-7648(2005)33%5B606%3Aeocpif%5D2.0.co%3B2

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