Grandparent helpers: the adaptive significance of older, post-dominant helpers in the Seychelles warbler

Richardson, David S. ORCID:, Burke, Terry and Komdeur, Jan (2007) Grandparent helpers: the adaptive significance of older, post-dominant helpers in the Seychelles warbler. Evolution, 61. pp. 2790-2800. ISSN 1558-5646

Full text not available from this repository. (Request a copy)


The possibility that older, often nonreproductive, individuals may engage in kin-directed cooperative behavior has been largely overlooked in the study of cooperative breeding. Here, we describe and investigate the adaptive significance of such “grandparent” helpers in the Seychelles warbler, the first bird species in which this phenomenon has been observed. On Cousin Island, over a period of 24 years, a significant proportion (13.7%) of females, but few males (3.0%), was deposed from dominant positions. Deposed females were replaced by related females. However there was no evidence that older, senescent females were stepping aside to gain greater fitness benefits by increasing the reproductive success of their offspring, rather than breeding themselves; deposed females were not postreproductive, nor was being deposed linked to age or reproductive senescence. Of the deposed females, 68% became subordinates and helped to raise group offspring, accounting for ca. 10% of subordinates in any year. Demoted females were related (r= 0.24) to the group offspring and, consequently, could gain indirect benefits through helping. As direct benefits appeared to be limited, we suggest that indirect benefits have driven the evolution of such “grandparent helpers.” This study now provides evidence for a new route to cooperative breeding in birds.

Item Type: Article
Faculty \ School: Faculty of Science > School of Biological Sciences
UEA Research Groups: Faculty of Science > Research Groups > Organisms and the Environment
Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation
Depositing User: EPrints Services
Date Deposited: 01 Oct 2010 13:38
Last Modified: 16 May 2023 00:50
DOI: 10.1111/j.1558-5646.2007.00222.x

Actions (login required)

View Item View Item