Data from: Changes in behavior are unable to disrupt a trophic cascade involving a specialist herbivore and its food plant

Changes in ecological conditions can induce changes in behavior and
demography of wild organisms, which in turn may influence population
dynamics. Black brant (Branta bernicla nigricans) nesting in colonies on
the Yukon–Kuskokwim Delta (YKD) in western Alaska have declined
substantially (~50%) since the turn of the century. Black brant are
herbivores that rely heavily on Carex subspathacea (Hoppner's sedge)
during growth and development. The availability of C. subspathacea affects
gosling growth rates, which subsequently affect pre‐ and postfledging
survival, as well as size and breeding probability as an adult. We
predicted that long‐term declines in C. subspathacea have affected gosling
growth rates, despite the potential of behavior to buffer changes in food
availability during brood rearing. We used Bayesian hierarchical
mixed‐effects models to examine long‐term (1987–2015) shifts in brant
behavior during brood rearing, forage availability, and gosling growth
rates at the Tutakoke River colony. We showed that locomotion behaviors
have increased (β = 0.05, 95% CRI: 0.032–0.068) while resting behaviors
have decreased (β = −0.024, 95% CRI: −0.041 to −0.007), potentially in
response to long‐term shifts in forage availability and brood density.
Concurrently, gosling growth rates have decreased substantially (β =
−0.100, 95% CRI: −0.191 to −0.016) despite shifts in behavior, mirroring
long‐term declines in the abundance of C. subspathacea (β = −0.191, 95%
CRI: −0.355 to −0.032). These results have important implications for
individual fitness and population viability, where shifts in gosling
behavior putatively fail to mitigate long‐term declines in forage
availability.