Foraging Theory as a Conceptual Framework for Studying Nest Predation

Abstract

Nest predation studies have typically documented patterns related to habitat characteristics rather than investigate predation as an interaction between predator and prey. In contrast, this article presents a simple model that seeks an explanation for variation in nest predation rates through an application of foraging theory. Changes in the environment or to the predator-prey community will manifest as measurable changes in, e.g., nest encounter rates, nest vigilance or defense, and the predator's search effort and strategy, and thus ultimately in the rate of nest predation. In accord with the model's predictions, (1) as the relative density of active nests declines so does predation by inefficient predators; (2) increasing the abundance of alternative foods decreases the nest predation rate; (3) decreasing the prey's food abundance increases predation by avian predators via the tradeoff between foraging and nest vigilance; and (4) nest site characteristics influence predation rates via changes in, e.g., nest encounter rates and recognition time. I argue that behavior and abiotic factors are important, but often neglected variables in our current conceptualization of avian nest predation.