Sex-specific Flexibility in Breeding and Helping Strategies in the Sociable Weaver (Philetairus socius)

Helping-at-the-nest is often viewed as a precursor to reproduction, but switching between breeder and helper roles has been documented in some species. Such flexibility should depend on the opportunities and benefits of helping, which could differ between sexes due to dispersal strategies and social structure. However, whether breeding-helping flexibility is widespread and sex-specific remains unknown. Here, we investigated sex-specific strategies in breeding-helping flexibility using a 10-year dataset (1955 individuals) on sociable weavers (Philetairus socius), a colonial cooperative breeder in which males are typically philopatric whereas females disperse. Both sexes helped for several years, with males helping more frequently than females and for twice as long (0-13 vs 0-10 years). Around 40% of non-dispersing birds never became breeders and 50% of individuals bred without helping first. Both sexes switched roles between- and within-seasons but males were more likely to alternate (respectively four and six times more than females and up 15 switches across seven years). Our study reveals important flexibility and sex differences in breeder-helper roles, consistent with sex-biased dispersal, spatial breeding proximity and possible indirect fitness benefits. These factors could play a role promoting the evolution of helping across life-stages, not only pre-reproduction, but also reproductive and post-reproductive individuals.