Enhancing Furbearer Management In New York
Management of furbearers presents numerous challenges due to their often elusive nature, relatively low population densities, and limited distributions. Improved knowledge of harvests, and harvest impacts on populations, can lead to enhanced management strategies that provide opportunities for sustainable use while conserving populations. We implemented a management action to explore the feasibility of providing fisher harvest opportunities beyond the traditional trapping season closure of December 10 th. An experimental management action was implemented to address the question of whether fisher-trapping effort, or capture vulnerability, would vary in a season extension. We collected over 100,000 trap nights of data and found no significant change in capture vulnerability, but that trapping effort, both in terms of number of active trappers and mean individual effort, was significantly lower during the extended portion of the seasons. Thus, we found that the addition of fisher harvest opportunities beyond December 10th does not increase cumulative harvest proportionally. We also developed a population model for a previously unexploited bobcat population. Survivorship parameters were estimated from harvest age structure using a Bayesian approach that allowed for the incorporation of external data and parameter updating as new data was made available. The posterior estimates of survivorship were incorporated into simulations of projection matrix models. The distribution of projected growth rates produced from the matrix model simulations showed decreasing variation in model projections as the survivorship information was refined. Ultimately, as more information was obtained, we refined our annual survivorship estimates to 0.81 (sigma=.006). Consequently, our estimated projected growth rates changed from lambda =0.93 (sigma=0.28) to λ=1.14 (sigma=0.014). Finally, we propose that understanding the population status of furbearers, and the impacts of management actions, is crucial for wildlife management agencies in fulfilling their obligations to society. We recommend what data are needed to gain this understanding and how these data can be collected from harvest-dependent sources. In this, we hope to demonstrate that the challenges of furbearer management are not insurmountable and to encourage agencies to developing strong, data-driven furbearer conservation programs that improve the management and stewardship of this resource.
dissertation or thesis