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Summertime resource selection and reproductive effects on survival of Ruffed Grouse

Mangelinckx, Joelle M., Davis, Samantha R. B., Allen, R. Bradford, Sullivan, Kelsey, Blomberg, Erik J.
TheAuk 2018 v.135 no.4 pp. 933-948
Bonasa umbellus, Rubus, birds, brood rearing, females, landscapes, males, reproduction, risk reduction, stems, summer, survival rate, vegetation cover, Maine
Theory suggests that animals should select resources on the basis of perceived fitness benefits, and avoid other available resources that may result in fitness costs. However, resource selection is both a scale- and a life-stage-specific process, in which the importance of different resources may vary among spatial scales of selection and phases of species' life cycles. We investigated multilevel resource selection and summer survival of Ruffed Grouse (Bonasa umbellus) in Maine, USA, to understand life-stage-specific resource selection and the cost of brood rearing. At the landscape level, male Ruffed Grouse selected areas with greater densities of woody stems taller than breast height, while females avoided these areas and selected areas with greater ground coverage by Rubus. Males further selected areas with greater stem densities at the local level, while females again avoided areas with greater stem densities and selected locally available areas with greater ground coverage by Rubus. Weekly survival rates (± SE) were reduced for females that were actively tending broods (S = 0.9393 ± 0.0294) when compared with nonreproductive individuals (both males and nonbrooded females; S = 0.9966 ± 0.0034). These differences in survival based on reproductive status were better supported than a difference associated solely with sex and resulted in a 69% chance that a female would survive raising a brood to 6 wk, compared with a 98% chance of survival for nonreproductive birds over the same 6 wk period. Our results suggest that male Ruffed Grouse selected resources that reduced their mortality risk, thereby investing in survival and their future reproductive potential, whereas brood-rearing females selected resources to benefit current reproduction and incurred a cost to their own survival in the process.