Meeting Abstract
In social species like the feral horse (Equus caballus), changes in individual behavior are likely to impact associated animals. On Shackleford Banks, NC, mares treated with the contraceptive agent porcine zona pellucida (PZP) demonstrate decreased fidelity to their band stallions. The potential impact of these PZP-related changes in female behavior on male behavior and physiology remains largely unexplored. We compared the frequency of male-male contests and physiological stress, measured by fecal cortisol levels, for males that had varying levels of experience with mare group changing behavior. Our data suggest that female group changing behavior does impact male fighting and cortisol levels, and these impacts may vary depending on home range ecology. In the East, a more open landscape with a history of territoriality, males associating with changing females fought more often. Conversely, in the West, where high dunes and dense brush limit visibility and horses share resources, female group changes seem to have no effect on male fighting. Across regions, males who experienced three group changes by females in a two week period exhibited increased cortisol levels during this time compared to stallions experiencing one or zero group changes. Further investigation of such behavioral and physiological effects will improve our understanding of the consequences of immunocontraception management for non-target animals.
