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4 April 2013 Inflated population density of island antechinus: a case of allochthonous marine inputs leading to increased food availability?
M. G. Sale, J. P. Y. Arnould
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Resource availability and other processes that affect maintenance, growth and decline of animal populations are central to ecology and conservation. This study quantified features indicative of population fitness and the availability of food resources for island and mainland populations of an insectivorous marsupial, the swamp antechinus (Antechinus minimus). The aim of the study was to test the hypothesis that colonial seabirds increase productivity of island habitats, ultimately providing greater food resources. The study found that antechinus biomass density was 4–13 times greater on the island site compared with the mainland site and was associated with higher recapture rates, suggesting that more individuals were surviving on the island during spring and summer months. An index of antechinus food availability (abundance and biomass of invertebrates) was also higher on the island site. Island antechinus also accessed marine food subsidies, in the form of seabird carrion, during the energetically demanding post-weaning growth period in spring and summer. Furthermore, based on soil nutrient and stable isotope analyses, there was strong evidence of nutrient enrichment from marine sources in the island ecosystem, commonly linked to increased productivity. Therefore, greater antechinus biomass and abundance on offshore islands are likely to be, in part, due to greater survival caused by higher availability of food resources.

© CSIRO 2012
M. G. Sale and J. P. Y. Arnould "Inflated population density of island antechinus: a case of allochthonous marine inputs leading to increased food availability?," Australian Journal of Zoology 60(5), 343-351, (4 April 2013).
Received: 30 July 2012; Accepted: 1 February 2013; Published: 4 April 2013

small mammal
stable isotope
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