Understanding the influences of immunocontraception of equids through competing models of behavior

Abstract

The rapid increase in human populations over the last several decades has lead to shrinking habitats and limited resources for many large vertebrates around the world. In response, managers seek effective tools for limiting population growth in some species, yet little is known about impacts of fertility control on the behavioral ecology of wild, free-roaming animals. Feral horses (Equus caballus) in the western United States are ideal candidates for contraceptive management due to broad scale federal protection, high fecundity, and finite public land allocated for them. The complex mating system of feral horses relies on behavioral manipulation of females by a polygynous male and a balance between reproductive and maintenance behaviors to promote fitness gains. I investigated influences of the immunocontraceptive porcine zona pellucida (PZP) on individual and social behavior within bands of feral horses in three discrete populations.