The impact of CWD on deer harvest and determining methods to estimate deer abundance
Date
2013
Authors
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Publisher
University of Delaware
Abstract
Chronic Wasting Disease (CWD) is a fatal neurological disease of North American deer species which has emerged as an important wildlife management issue. In 2010, a hunter harvested deer in Allegany County, Maryland tested positive for the disease. Herein, I examine 2 important aspects of CWD management in the state of Maryland. The first objective was to determine the impact of human dimensions, specifically negative hunter attitude towards CWD and restrictive management regulations, on deer harvest throughout the state. I used an attitude study completed by Responsive Management (Harrisonburg, VA) to identify hunters in 3 counties (Allegany, Garrett, and Dorchester) of varying proximity to the disease. Hunters were asked if and how CWD had caused them to alter their harvest behavior. I then linked each individual’s response to their harvest history to determine the degree to which negative hunter attitude had reduced deer harvest. The amount of hunters who claimed to have changed their behavior due to CWD ranged from 14.08% in Dorchester County to 22.63% in Allegany County, suggesting distance to the disease affected attitude. In Allegany County, CWD caused a 6.95% average decrease in the annual harvest, which falls well within the normal stochastic variability in annual harvest. I observed no reduction in deer harvest attribuTable to CWD in Garrett or Dorchester Counties. My findings suggest that reduction in deer harvest after the discovery of CWD due to negative hunter attitude is highly localized near the disease management area and has little impact on deer management.
My second objective was to evaluate 3 common methods (spotlight and thermal-imaging road-based distance sampling and motion-triggered camera surveys) for estimating deer density and demographic parameters. I performed all 3 methods concurrently during 2 week sampling periods. Sampling periods occurred in August 2012, February 2013, and August 2013. Methodology comparison incorporated point estimates, measures of precision, detection probability, and cost. Camera surveys appeared to overestimate deer density, provided no measures of precision, and had a higher cost than road-based surveys. Spotlight surveys were affordable but required substantial effort to achieve the precision necessary for management decisions. Thermal-imaging surveys had greater detection probabilities relative to spotlight surveys and required less effort to achieve sufficient precision. I recommend road-based distance sampling incorporating thermal-imaging technology to estimate deer demographic parameters at the disease management unit scale.
Description
Keywords
Chronic wasting disease, White-tailed deer, Hunter attitude, Population management