Data from: Peregrine Falcons shift mean and variance in provisioning in response to increasing brood demand

The hierarchical model of provisioning posits that parents employ a
strategic, sequential use of three provisioning tactics as offspring
demand increases (e.g., due to increasing brood size and age). Namely,
increasing delivery rate (reducing intervals between provisioning visits),
expanding provisioned diet breadth, and adopting variance-sensitive
provisioning. We evaluated this model in an Arctic breeding population of
Peregrine falcons (Falco peregrinus tundrius) by analyzing changes in
inter-visit-intervals (IVIs) and residual variance in IVIs across 7 study
years. Data was collected using motion-sensitive nest camera images and
analyzed using Bayesian mixed effect models. We found strong support for a
decrease in IVIs (i.e., increase in delivery rates) between provisioning
visits and an increase in residual variance in IVIs with increasing
nestling age, consistent with the notion that peregrines shift to
variance-prone provisioning strategies with increasing nestling demand.
However, support for predictions made based on the hierarchical model of
tactics for coping with increased brood demand was equivocal as we did not
find evidence in support of expected covariances between random effects
(i.e., between IVI to an average-sized brood (intercept), change in IVI
with brood demand (slope) or variance in IVI). Overall, our study provides
important biological insights into how parents cope with increased brood
demand.