Time to Reduction: Factors Influencing Management Efficacy in Sterilizing Overabundant White-Tailed Deer

Abstract

In managing overabundant white-tailed deer (Odocoileus virginianus), fertility control frequently is regarded as a viable alternative to lethal strategies. However, little information is available concerning expected duration of fertility control. Our objectives were to create a flexible model for application in a diverse array of environmental conditions, determine the extent to which various parameters contributed to population growth, and assess the time necessary to reduce a population to a given level. The modeled population was assumed geographically closed without density dependence. Using prospective perturbation analysis on a linear time-invariant Lefkovitch matrix model, survival rates contributed to overall population growth nearly twice that of birth rates. Using numerical analysis, a general relationship between annual sterilization rate, desired population reduction, and time to that reduction was determined. This relationship was nonlinear and showed decreased efficiency per unit effort. Depending on local parameter values, we determined that a population could be reduced by 30% to 60% in 4-10 years if a manager could sterilize 25-50% of available fertile females annually. Thus, sterilization may be a viable option for communities with the financial resources and political will to sterilize.