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Low survival rates of Swan Geese (Anser cygnoides) estimated from neck-collar resighting and telemetry

September 1, 2016

Waterbird survival rates are a key component of demographic modeling used for effective conservation of long-lived threatened species. The Swan Goose (Anser cygnoides) is globally threatened and the most vulnerable goose species endemic to East Asia due to its small and rapidly declining population. To address a current knowledge gap in demographic parameters of the Swan Goose, available datasets were compiled from neck-collar resighting and telemetry studies, and two different models were used to estimate their survival rates. Results of a mark-resighting model using 15 years of neck-collar data (2001–2015) provided age-dependent survival rates and season-dependent encounter rates with a constant neck-collar retention rate. Annual survival rate was 0.638 (95% CI: 0.378–0.803) for adults and 0.122 (95% CI: 0.028–0.286) for first-year juveniles. Known-fate models were applied to the single season of telemetry data (autumn 2014) and estimated a mean annual survival rate of 0.408 (95% CI: 0.152–0.670) with higher but non-significant differences for adults (0.477) vs. juveniles (0.306). Our findings indicate that Swan Goose survival rates are comparable to the lowest rates reported for European or North American goose species. Poor survival may be a key demographic parameter contributing to their declining trend. Quantitative threat assessments and associated conservation measures, such as restricting hunting, may be a key step to mitigate for their low survival rates and maintain or enhance their population.

Publication Year 2016
Title Low survival rates of Swan Geese (Anser cygnoides) estimated from neck-collar resighting and telemetry
DOI 10.1675/063.039.0307
Authors Chang-Yong Choi, Ki-Sup Lee, Nikolay D. Poyarkov, Jin-Young Park, Hansoo Lee, John Y. Takekawa, Lacy M. Smith, Craig R. Ely, Xin Wang, Lei Cao, Anthony D. Fox, Oleg Goroshko, Nyambayar Batbayar, Diann J. Prosser, Xiangming Xiao
Publication Type Article
Publication Subtype Journal Article
Series Title Waterbirds
Index ID 70182088
Record Source USGS Publications Warehouse
USGS Organization Patuxent Wildlife Research Center