UCSC-SOE-10-30: A state dependent life-history model of provisioning in penguins

Katherine A. Cresswell, John R. Wiedenmann, and Marc Mangel
11/01/2010 09:00 AM
Applied Mathematics & Statistics
There is a wealth of information detailing the behavior of penguins in the Southern Ocean during breeding. However, we have less of an idea how their behavior is affected by changes in prey availability. The aim of management models in this region is to allocate catch limits for one of the main prey species for penguins, Antarctic krill (Euphausia superba), in defined units around major breeding colonies. Our main goal is to estimate the shape of the functional response of penguins and krill, key information that is currently missing from management. We use data from field studies on penguins and acoustic readings of krill swarms to characterize a state-dependent life-history model where two penguin parents forage to provision a chick to fledging. Each individual parent makes decisions based on quantified estimates of state dynamics, a probabilistic distribution of how their partner is behaving, and a need to maximize fitness. We predict that the shape of the curve describing total amount of krill eaten versus krill available around a breeding colony approximates a Holling Type III functional response. Our broader prediction is that the age of parents can influence chick survival, but only at medium food levels.