Ecology of elk parturition across winter feeding opportunities in the brucellosis endemic area of Wyoming

Abstract

This study was initiated to examine parturition related behavior both from an ecological perspective and to investigate implications for brucellosis transmission risk among elk and between elk and cattle. These aspects were investigated for elk fed during the winter, elk using improved winter feedlines, and free-ranging elk. Brucellosis is a disease causing abortion in elk (Cervus elaphus nelsoni), bison (Bos bison), and cattle (Bos spp.). The most common transmission route is through oral contact with aborted fetuses or parturition tissues/fluids and transmission risk is dependent on contact rates. Vaginal implant transmitters were deployed on winter free-ranging elk and elk using feedgrounds to define parturition and abortion sites. Habitat variables were collected and modeled for parturition sites at the microhabitat and macrohabitat spatial scale on the basis of biotic, abiotic, and anthropogenic factors. We collected data on a total of 169 parturition sites, representing the largest ever study of elk calving behavior. Elk were selective with respect to parturition habitat at both macrohabitat and microhabitat scales but we did not find evidence for differences in selection behavior among feeding types. Parturition site selection appears to be driven by cover rather than by forage at both scales. Use of feedgrounds and length of feeding season were associated with decreased distance from winter range and increased clustering of parturition locations. This study will facilitate evaluation and development of best management practices regarding feedground management, elk, habitat manipulation, and risk of brucellosis transmission.