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Influence of shelf oceanographic variability on alternate foraging strategies in long-nosed fur seals

journal contribution
posted on 2023-05-20, 05:07 authored by Dahlia FooDahlia Foo, McMahon, C, Mark HindellMark Hindell, Goldsworthy, S, Bailleul, F
Central place foragers often change their foraging behaviour in response to changes in prey availability in the environment. Lactating long-nosed fur seals Arctocephalus forsteri (LNFS) at Cape Gantheaume in South Australia have been observed to display alternate foraging strategies, whereby they forage on the shelf in summer and switch to oceanic foraging in winter. We investigated the relationship between changes in shelf summertime upwelling and the timing and variability when females switch from predominantly shelf to oceanic foraging. Geolocation tags were deployed on females from summer to winter in 2016 and 2017, giving us longitudinal tracks over the transition period. The timing of switching from shelf to oceanic foraging was primarily driven by seasonal oceanographic changes on the shelf—specifically when the strength of the seasonal localised upwelling began to decline. The individual variability in the timing of the switch was driven by the strength of the coastal upwelling, with variability being greater in years when upwelling strength was weaker. By comparing our results to those of previous studies on the same colony, we found qualitative evidence that inter-annual environmental variability likely influences whether individuals display a single or multiple foraging strategies. This further highlights the flexibility in foraging strategies used by LNFS in response to environmental changes. The effect of inter-annual differences in foraging strategies on overall reproductive success warrants further investigation.

Funding

Holsworth Wildlife Research Endowment

History

Publication title

Marine Ecology - Progress Series

Volume

615

Pagination

189-204

ISSN

0171-8630

Department/School

Institute for Marine and Antarctic Studies

Publisher

Inter-Research

Place of publication

Nordbunte 23, Oldendorf Luhe, Germany, D-21385

Rights statement

© Inter-Research 2019

Repository Status

  • Restricted

Socio-economic Objectives

Assessment and management of terrestrial ecosystems; Ecosystem adaptation to climate change