VERY HIGH DENSITIES OF MULE DEER (ODOCOILEUS HEMIONUS) ASSOCIATED WITH SUBURBAN DEVELOPMENT IN MARIN COUNTY, CALIFORNIA

Brett J Furnas; California Department of Fish and Wildlife; brett.furnas@wildlife.ca.gov; Russ H. Landers, Stuart S. Itoga, Benjamin N. Sacks

In contrast to white-tailed deer (Odocoileus virginianus) of eastern North America, which are usually considered over-abundant and at nuisance levels, concern typically expressed about mule deer (Odocoileus hemionus) in California is that they have declined in abundance over the last 50 years. This may be true for some migratory herds, but abundant deer near coastal cities pose potential for human-wildlife conflict. To examine potential causes of high density in a coastal population of deer throughout Marin County, California, we used fecal DNA surveys during 2015-2016 and spatial capture-recapture modeling. We estimated an average density of 18.9 (90%CI: 16.4-21.4) resident deer per square kilometer, which was four times greater than recently found for migratory deer in interior mountains of the state. Deer density in Marin was positively associated with oak habitats and human density up to approximately 500 people per square kilometer. Visual assessment of body condition using cameras suggests deer were not limited nutritionally. Coyote detections from cameras were more strongly correlated with fawns than adult deer. These results suggest the highest densities of deer found in southeastern Marin were strongly associated with suburban development within oak woodlands. Future research should investigate population growth rate and potential effects of coyote predation on recruitment.

Urban Wildlife Management