Paper > Paper > Low Survival Rates of Swan Geese (Anser cygnoides) Estimated from Neck-collar Resighting and Telemetry

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  Low Survival Rates of Swan Geese (Anser cygnoides) Estimated from Neck-collar Resighting and Telemetry
  Writer : KOECO     Date : 16-11-10 20:18     Count : 1497    
   201609_Waterbirds_Low_survival_rate_of_Swan_Geese.pdf (579.1K), Down : 17, 2016-11-10 20:18:39

Low Survival Rates of Swan Geese (Anser cygnoides) Estimated from Neck-collar Resighting and Telemetry


Abstract

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.


Source: Waterbirds, 39(3):277-286.
Published By: The Waterbird Society


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