Variation of annual apparent survival and detection rates with age, year, and individual identity in male Weddell seals (Leptonychotes weddellii) from long-term mark-recapture data

Population Ecology
By: , and 

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Abstract

Exploring age- and sex-specific survival rates provides insight regarding population behavior and life-history trait evolution, but many population studies exclude males. Accordingly, our understanding of how age-specific patterns of survival, including actuarial senescence, compare between the sexes remains inadequate. Using 35 years of mark-recapture data for 7,516 male Weddell seals (Leptonychotes weddellii) born in Erebus Bay, Antarctica, we estimated age- specific annual survival rates using a hierarchical model for mark-recapture data in a Bayesian framework. Our male survival estimates were moderate for pups and yearlings, highest for 2- year-olds, and gradually declined with age thereafter such that the oldest animals observed had the lowest rates of any age. Reports of senescence in other wildlife populations of species with similar longevity occurred at older ages than those presented here. When compared to recently published estimates for reproductive Weddell seal females, we found that peak survival rates were similar (males: 0.94, 95% CI = 0.92-0.96; females: 0.92, 95% CI = 0.93-0.95), but rates declined more rapidly in males. Costs of reproduction for males seem to exceed costs incurred by females, but age-specific reproductive data for males are necessary to fully evaluate survival- reproduction tradeoffs in males. Similar studies on a broad range of species are needed to contextualize these results for a better understanding of the variation in senescence patterns between the sexes of the same species, but our study adds information for a marine mammal species to a research topic dominated by avian and ungulate species.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Variation of annual apparent survival and detection rates with age, year, and individual identity in male Weddell seals (Leptonychotes weddellii) from long-term mark-recapture data
Series title Population Ecology
DOI 10.1002/1438-390X.12036
Volume 62
Issue 1
Year Published 2020
Language English
Publisher Wiley
Contributing office(s) Patuxent Wildlife Research Center
Description 17 p.
First page 134
Last page 150
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