Comparison of methods for estimating bird abundance and trends from historical count data
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Journal of Wildlife Management. 72(8): 1674-1682.
The use of bird counts as indices has come under increasing scrutiny because assumptions concerning detection probabilities may not be met, but there also seems to be some resistance to use of model-based approaches to estimating abundance. We used data from the United States Forest Service, Southern Region bird monitoring program to compare several common approaches for estimating annual abundance or indices and population trends from point-count data. We compared indices of abundance estimated as annual means of counts and from a mixed-Poisson model to abundance estimates from a count-removal model with 3 time intervals and a distance model with 3 distance bands. We compared trend estimates calculated from an autoregressive, exponential model fit to annual abundance estimates from the above methods and also by estimating trend directly by treating year as a continuous covariate in the mixed-Poisson model. We produced estimates for 6 forest songbirds based on an average of 621 and 459 points in 2 physiographic areas from 1997 to 2004.
Keywordsabundance detection probability distance models point counts Poisson models removal models songbirds Southeastern United States
Thompson, Frank R., III; La Sorte, Frank A. 2008. Comparison of methods for estimating bird abundance and trends from historical count data. Journal of Wildlife Management. 72(8): 1674-1682. https://doi.org/10.2193/2008-135.