Effects of roundups on behavior and reproduction of feral horses

Abstract

Roundups are used to maintain feral horse populations in balance with rangeland grazing capacity, but little is known about short-term and long-term effects of roundups on horses. We evaluated the effects of roundups on behavior and reproduction of feral horses. The study was conducted near Challis, Ida. during 1994-1995, and repeated near Lander, Wyo. during 1995-1996. Horses were randomly assigned to 3 different treatment groups. One group (ADOPTED) was gathered by a Bureau of Land Management roundup crew using a helicopter. These horses were removed and placed in the Adopt-A-Horse Program. The second group (SIMULATED) consisted of horses that were gathered by helicopter, but these horses evaded capture and remained in the study area after the roundup. Horses in the third group (CONTROL) were not herded by helicopter. Horse behavior was monitored in the SIMULATED and CONTROL groups before and after roundups. Behavioral variables analyzed were the percentage of time spent resting, feeding, vigilant, traveling, and engaged in agonistic encounters. Neither foraging or social behavior of feral horses was affected by roundups in either study area (P > 0.10). Reproduction was monitored within the SIMULATED, CONTROL, and ADOPTED groups during the year following roundups. The percentages of mares with live foals did not differ (P > 0.10) among the 3 treatment groups in Idaho or Wyoming. Foaling success rates in Idaho were 29%, 31%, and 43% for CONTROL, ADOPTED, and SIMULATED mares, respectively. In Wyoming, foaling success rates were 29%, 42%, and 48% for CONTROL, ADOPTED, and SIMULATED groups, respectively. We found no evidence that roundups had deleterious effects on behavior or reproduction of feral horses.