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J Anim Ecol. 2016 Sep;85(5):1340-51. doi: 10.1111/1365-2656.12539. Epub 2016 Jun 20.

The price of associating with breeders in the cooperatively breeding chestnut-crowned babbler: foraging constraints, survival and sociality.

Author information

1
Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
2
Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, 58183, Sweden.
3
Fowlers Gap Arid Zone Research Station, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
4
Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn, TR10 9FE, UK.

Abstract

Understanding the costs of living with breeders might offer new insights into the factors that counter evolutionary transitions from selfish individuals to cooperative societies. While selection on early dispersal is well understood, it is less clear whether costs are also associated with remaining with family members during subsequent breeding, a prerequisite to the evolution of kin-based cooperation. We propose and test the hypothesis that living in groups containing breeders is costly and that such costs are exacerbated by increasing group size. For example, in group-living central-place foragers, group members might suffer from resource depletion when foraging in a restricted area during breeding and significant costs of repeatedly travelling between foraging patches and the site of offspring. Using the cooperatively breeding chestnut-crowned babbler (Pomatostomus ruficeps), for which grouping during breeding is obligatory, we show that reproduction is associated with substantially reduced foraging areas and evidence of resource depletion, particularly in larger groups. Such effects largely persisted from the onset of incubation through to offspring independence 4-5 months later. All group members, irrespective of their breeder or helper status, lost significant body mass over this period, and, in males, mass loss was associated with reduced interannual survival. Although babblers are constrained from living outside of breeding groups due to high risks of predation and the poor success of breeding without helpers, we suggest that the effects we describe may generally select against group living during breeding attempts in species where constraints to independent breeding and costs of dispersal are less acute.

KEYWORDS:

benefits-of-philopatry; ecological constraints; family living; habitat saturation; kin competition; movement patterns

PMID:
27136301
DOI:
10.1111/1365-2656.12539
[Indexed for MEDLINE]

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