Predator control, mesopredator release, and impacts on bird nesting success: a field test

Abstract

ABSTRACT The mesopredator release hypothesis predicts that reductions in top-predator abundance in a community will increase the abundance or activity of smaller ‘mesopredators’, and increase predation pressure on mesopredator prey, including bird nests. Top predators have been extensively controlled in rangelands managed for sheep in South Africa, because top predators prey on sheep. To test whether this control of top predators has increased nest predation risk for breeding birds in rangeland landscapes, I compared nest predation rates between rangeland areas subject to predator control, and large protected areas with no predator control. An artificial nest experiment found that nest predation by mammalian mesopredators was non-significantly higher in rangeland areas, providing weak support for increased predation by mammalian mesopredators as a consequence of mesopredator release. However, nest predation rates on natural nests of a suite of nine species did not differ between rangeland and protected ar...