Status and trends of American Woodcock Scolopax minor populations in the eastern and central US and Canada are monitored via a Singing-ground Survey , conducted just after sunset along roadsides in spring. Annual analyses of the survey produce estimates of trend and annual indexes of abundance for 25 states and provinces, eastern and central management regions, and survey-wide. In recent years, a log-linear hierarchical model that defines year effects as random effects in the context of a slope parameter (the S Model) has been used to model population change. Recently, alternative models have been proposed for analysis of Singing-ground Survey data. Analysis of a similar roadside survey, the North American Breeding Bird Survey , has indicated that alternative models are preferable for almost all species analyzed in the Breeding Bird Survey. Here, we use leave-one-out cross validation to compare model fit for the present Singing-ground Survey model to fits of three alternative models, including a model that describes population change as the difference in expected counts between successive years (the D model) and two models that include t -distributed extra-Poisson overdispersion effects (H models) as opposed to normally-distributed extra-Poisson overdispersion. Leave-one-out cross validation results indicate that the D model was favored by the Bayesian predictive information criterion but a pairwise t -test indicated that model D was not significantly better-fitting to Singing-ground Survey data than the S model. The H models are not preferable to the alternatives with normally-distributed overdispersion. All models provided generally similar estimates of trend and annual indexes suggesting that, within this model set, choice of model will not lead to alternative conclusions regarding population change. However, as in Breeding Bird Survey analyses, we note a tendency for S model results to provide slightly more extreme estimates of trend relative to D models. We recommend use of the D model for future Singing-ground Survey analyses.
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Research Article|
March 16 2021
Estimation Of Annual Indexes of Abundance and Trend From The American Woodcock Singing-Ground Survey: Comparison Of 4 Models
John R Sauer
;
John R Sauer
Eastern Environmental Science Center
12100 Beech Forest Road
UNITED STATES
Laurel
MD
20770
3014975545
3014975662
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William A. Link
;
William A. Link
USGS Patuxent Wildlife Research Center, 12100 Beech Forest Road, Laurel, MD 20770
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Mark E. Seamans
;
Mark E. Seamans
US Fish and Wildlife Service, Division of Migratory Bird Management, Lakewood, CO, 80225
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Rebecca D. Rau
Rebecca D. Rau
US Fish and Wildlife Service, Division of Migratory Bird Management, Laurel, MD, 20770
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Journal of Fish and Wildlife Management (2021)
Article history
Received:
October 21 2020
Revision Received:
February 27 2021
Accepted:
February 27 2021
Citation
John R Sauer, William A. Link, Mark E. Seamans, Rebecca D. Rau; Estimation Of Annual Indexes of Abundance and Trend From The American Woodcock Singing-Ground Survey: Comparison Of 4 Models. Journal of Fish and Wildlife Management 2021; doi: https://doi.org/10.3996/JFWM-20-079
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