Intragroup competition predicts individual foraging specialisation in a group-living mammal

Catherine E. Sheppard, Richard Inger, Robbie A. McDonald, Sam Barker, Andrew L. Jackson, Faye J. Thompson, Emma I. K. Vitikainen, Michael A. Cant, Harry H. Marshall

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Abstract

Individual foraging specialisation has important ecological implications, but its causes in group-living species are unclear. One of the major consequences of group living is increased intragroup competition for resources. Foraging theory predicts that with increased competition, individuals should add new prey items to their diet, widening their foraging niche (‘optimal foraging hypothesis’). However, classic competition theory suggests the opposite: that increased competition leads to niche partitioning and greater individual foraging specialisation (‘niche partitioning hypothesis’). We tested these opposing predictions in wild, group-living banded mongooses (Mungos mungo), using stable isotope analysis of banded mongoose whiskers to quantify individual and group foraging niche. Individual foraging niche size declined with increasing group size, despite all groups having a similar overall niche size. Our findings support the prediction that competition promotes niche partitioning within social groups and suggest that individual foraging specialisation may play an important role in the formation of stable social groupings.

©2018 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See http://creativecommons.org/licenses/by/4.0/
Original languageEnglish
JournalEcology Letters
Early online date14 Mar 2018
DOIs
Publication statusE-pub ahead of print - 14 Mar 2018

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