AMLR Temperature Recording Archival Tags Gentoos 2005-2008 v1.2

Estimates of daily activity and consequent demand for food during winter are scarce for many polar seabirds, yet essential for assessing constraints on foraging effort, demand for food, and potential competition with local fisheries. We affixed archival temperature tags to gentoo penguins (Pygoscelis papua) from two colonies in the South Shetland Islands to measure the frequency, timing, and duration of foraging trips and to estimate minimum food requirements during winter. Foraging trip frequencies ranged from 0.85 to 1.0 trips day-1 and were positively correlated with day length. Early winter foraging trips more closely matched day length than late winter foraging trips. The data suggest that individuals maximize foraging time during the early winter period, likely to recover body mass following the breeding season and molt. The more attenuated response of foraging trip durations to increasing day length in late winter may be related to differences in local resource availability or individual behaviors prior to the upcoming breeding season. Minimum food requirements also exhibited a seasonal cycle with a mid-winter minimum. On average, minimum food requirements were estimated at 0.70 ± 0.12 kg day-1. Extrapolated to the regional population of gentoo penguins, winter food requirements by gentoo penguins were equivalent to roughly 33% of annual krill catches by commercial fisheries in the South Shetland Island region over the past decade. Current expansion of the gentoo population and the krill fishery in the southern Scotia Sea warrants continued monitoring of gentoo penguins during winter.

We use temperature-recording archival tags to measure the basic activity patterns of gentoo penguins from two breeding colonies in the South Shetland Islands during the 2005, 2006, and 2008 austral winters. We first ask whether foraging trip frequencies, timing, and durations during winter differ across space and time. We then examine the relationship of trip durations with day length to assess how rapid changes in day length during winter affect foraging behavior. Finally, from the observations of daily activity, we estimate the minimum food requirements that are necessary to meet daily energy expenditures associated with the observed daily activity.

Hinke, J.T. and W.Z. Trivelpiece. 2011. Daily activity and minimum food requirements during winter for gentoo penguins (Pygoscelis papua) in the South Shetland Islands, Antarctica. Polar Biol (2011) 34:1579-1590.

DOI 10.1007/s00300-011-1018-x

NCEI data archive: https://doi.org/10.7289/V50G3H6Z

Available online at https://www.fisheries.noaa.gov/about/antarctic-ecosystem-research-division-southwest-fisheries-science-center

https://www.fisheries.noaa.gov/about/antarctic-ecosystem-research-division-southwest-fisheries-science-center

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Data collected using recognized protocols.