U.S. Department of Agriculture: Animal and Plant Health Inspection Service
Date of this Version
5-17-2005
Abstract
Occurrences of disease outbreaks within and near captive cervid (mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni)) farms have recently drawn attention to these facilities. Some state wildlife and agricultural agencies have pondered making double fencing mandatory or otherwise increasing regulation of captive operations. Diseases such as Chronic Wasting Disease (CWD) and Bovine Tuberculosis (bovine TB) are a threat to captive and free-ranging cervid populations. Concerns over these and other diseases being transmitted from captive to wild cervids, and vice versa, have increased. In most cases, captive cervids are separated from wild cervid populations by a single fence, which could allow direct contact between populations through the fence. Transmission of CWD appears to be primarily from animal to animal (Williams and Young 1992, Spraker et al. 1997, Miller and Williams 2003, Miller and Wild 2004) and is likely density dependent (Peterson et al. 2002, Williams et al. 2002). Fence-line contact is believed to be a means of transmission of CWD between wild and free-ranging cervids (Miller and Thorne 1993, Williams et al. 2002, Williams and Miller 2003). Fence-line contact is also a concern in the transmission of bovine TB (Rhyan et al. 1995), as the most common means of transmission being through inhalation (Sauter and Morris 1995, Palmer et al. 1999, Clifton-Hadley et al. 2001, Palmer et al. 2003). Through the use of track plots and motion-activated video, we evaluated interactions between farmed and wild cervids through fences. Our primary objective was to establish how much contact occurs between captive and wild cervids. We conducted the study on 15 private deer and elk ranches, ranging in size from 3 - 464 hectares, in northern Michigan and across southwestern and northern Colorado. Six of the study sites were white-tailed deer ranches in Michigan and 9 were elk ranches in Colorado. We collected track-plot data bi-weekly and video data continuously. Track plot data revealed where animals shared the same space during a 24-hr period and video data showed physical contacts and distances among cervids. We divided the year into 4 time periods for Colorado data (spring migration/calving, summer, rut/fall migration, and winter) and 2 time periods for Michigan data (summer and winter). Colorado trackplot data revealed that most activity for captive elk was in the spring. Colorado and Michigan free-ranging elk and deer activity was somewhat variable across all seasons according to trackplot data. Preliminary camera data suggest that interactions are more frequent between farmed and wild elk than between farmed and wild white-tailed deer. In conclusion we found considerable variation from site-to-site in the species, sex, age class, and 34 number of wild cervids frequenting cervid facility fence lines. Elevation, habitat type, and proximity to prime habitat appeared to play a role in the time of year that the interactions took place. Cervid facility management practices (animal stocking rates, proximity of males to females, feeding practices, and fence construction) also had a strong effect on fence-line activity.
Comments
Published by Proceedings of the 11th Wildlife Damage Management Conference. (D.L. Nolte, K.A. Fagerstone, Eds). 2005. Permission to use.