Abstract
Nonbreeding helpers can greatly improve the survival of young and
reproductive fitness of breeders in many cooperatively breeding species.
Breeder turnover, in turn, can have profound effects on dispersal
decisions made by helpers. Despite its importance in explaining group size
and predicting population demography of cooperative breeders, our current
understanding of how individual traits influence animal behavior after
disruptions to social structure is incomplete particularly for terrestrial
mammals. We used 12 years of genetic sampling and group pedigrees of gray
wolves (Canis lupus) in Idaho, USA, to ask questions about how breeder
turnover affected the apparent decisions by mature helpers
(>2-year-old) to stay or leave a group over a one-year time
interval. We found that helpers showed plasticity in their responses to
breeder turnover. Most notably, helpers varied by sex and appeared to base
dispersal decisions on the sex of the breeder that was lost as well. Male
and female helpers stayed in a group slightly more often when there was
breeder turnover of the same sex, although males that stayed were often
recent adoptees in the group. Males, however, appeared to remain in a
group less often when there was breeding female turnover likely because
such vacancies were typically filled by related females from the males’
natal group (i.e., inbreeding avoidance). We show that helpers exploit
instability in the breeding pair to secure future breeding opportunities
for themselves. The confluence of breeder turnover, helper sex, and
dispersal and breeding strategies merge to influence group composition in
gray wolves.