nerc.ac.uk

Dietary divergence is associated with increased intra-specific competition in a marine predator

Ratcliffe, Norman; Adlard, Stacey; Stowasser, Gabriele; McGill, Rona. 2018 Dietary divergence is associated with increased intra-specific competition in a marine predator. Scientific Reports, 8, 6827. 10, pp. https://doi.org/10.1038/s41598-018-25318-7

Before downloading, please read NORA policies.
[img]
Preview
Text
Ratcliffe.pdf - Published Version
Available under License Creative Commons Attribution 4.0.

Download (1MB) | Preview

Abstract/Summary

Optimal foraging theory predicts that when food is plentiful all individuals should take a small range of preferred prey types, but as competition increases less preferred prey will be included in the diet. This dietary switching may not be uniform among individuals, which produces discrete dietary clusters. We tested this hypothesis for gentoo penguins at Bird Island, South Georgia, using stable isotope analysis and biologging. Competition, in the form of the density of foraging dives, increased markedly from incubation to chick-rearing owing to increased foraging effort. Birds responded behaviourally by exploiting a greater portion of the available foraging radius and increasing dive depths. Dietary niche width doubled and two discrete dietary clusters appeared; one comprising birds that consumed mostly krill and another that ate a greater proportion of demersal fish. There were no differences in morphology between the dietary classes, but birds in the fish class had a tendency to dive deeper, which suggests a behavioural basis for specialization. Our findings are consistent with the hypothesis that intra-specific competition expands the population’s dietary niche width and drives divergence in diets among individuals.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.1038/s41598-018-25318-7
ISSN: 20452322
Date made live: 08 May 2018 08:47 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/519868

Actions (login required)

View Item View Item

Document Downloads

Downloads for past 30 days

Downloads per month over past year

More statistics for this item...