Multi-state mark-recapture models as a novel approach to estimate factors affecting attendance patterns of lactating subantarctic fur seals from Marion Island

• Published in: Antarctic Science
• Main Authors: Wege, M., Nevoux, M., de Bruyn, P.J.N., Bester, M.N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2014
• Subjects: Geology; Ecology, Evolution, Behavior and Systematics; Oceanography; Antarctic Science; Marion Island
• Online Access: http://dx.doi.org/10.1017/s0954102014000716; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102014000716

Abstract Observer-based studies often underestimate key ecological parameters. Here a fresh approach was used to analyse six years (2006–11) of attendance cycles to estimate foraging trip lengths of a lactating flipper-tagged otariid: subantarctic fur seals at Marion Island. Multi-state mark-recapture models were used to calculate detection failures of females, correct estimates accordingly, and investigate the effects of year, season, pup sex and the presence of a telemetry device on attendance cycle parameters. There were no differences between corrected and uncorrected attendance data. This is attributed to the high capture probability across all seasons (range: 83–98%). This illustrates that observer-based studies are useful to augment telemetry studies. Only season and pup sex had a significant impact on female provisioning rates. In winter, foraging trip durations were longer ( t -value=25.22, P <0.0001) and attendance durations shorter ( t -value=-2.15, P =0.01) than during summer. Females with female pups spent a higher proportion of their time on land (χ 2 =6.6, P <0.05). Male pups have higher growth demands and are larger which suggests they can deplete female milk-stores faster.