9th International Deer Biology Congress

AUTHORS: Aaron M. Foley, Caesar Kleberg Wildlife Research Institute, Texas A&M University–Kingsville and East Foundation; David G. Hewitt, Charles A. DeYoung and Randy W. DeYoung – Caesar Kleberg Wildlife Research Institute, Texas A&M University–Kingsville; Matthew J. Schnupp, King Ranch Inc.

ABSTRACT: Chronic wasting disease (CWD) is a transmissible disease that affects members of the Cervid family. Recently, multiple cases of CWD have been discovered in captive white-tailed deer facilities in Texas. There is concern about how CWD would impact free-ranging deer populations especially in South Texas where the variable rainfall results in variable and, on average, low fawn recruitment rates. We developed a model based on data from 55,505 ha of rangelands where deer harvests were light (~2%), no supplemental feed was provided, and deer counts were conducted annually for 20 years. Our models with survival rates, fawn:doe ratios, and rates of hunter harvest produced projections that were comparable with observed trends. CWD parameters were inputted into the model based on data from CWD-afflicted states. Initial prevalence was set at 1% of the population with a 0.26% increase in prevalence per year and mortalities occurred 1-3 years after being infected. With no CWD and no harvest, populations increased 1.43% annually and the population was able to sustain a 2% annual rate of harvest. Incorporation of CWD did not result in a decline in population size if there was no harvest; however, populations declined when 1% harvest of both sexes occurred. Limiting harvest to males did not cause populations to decline but proportion of mature males declined because males are more susceptible to CWD. Our results indicated that if CWD emerged in free-ranging deer populations in South Texas, the economics and culture of deer management and recreational hunting would be altered.