Effects of lethal management on behaviors, social networks, and movements of overabundant white-tailed deer

Date of Completion

January 2008

Keywords

Agriculture, Forestry and Wildlife

Degree

Ph.D.

Abstract

I investigated the impacts of lethal management on behaviors, social affiliations, and resulting susceptibility to vehicle collisions of overabundant white-tailed deer using Global Positioning System collars. I compared weekly kernel home range sizes, 1-hour movements, and escape distances during controlled hunting in one herd (65% reduction) and sharpshooting (91% reduction) in another. Weekly home ranges increased during controlled hunting (F13=4.6, p<0.001) and normalized thereafter. Weekly home ranges did not differ during sharpshooting, but increased 2-weeks post-shoot (F13=2.4, p<0.005). Mean 1-hour movements and escape distances differed for both herds during lethal management. Deer exposed to sharpshooting increased home range size by more than 400% 1-year post-shoot. Results suggest that sharpshooting techniques educate fewer animals, allowing for more efficient and greater herd reduction. ^ Daily minimum convex polygon home ranges were estimated for each animal for each of 42 days encompassing lethal removals for both herds. Daily home range overlap for each deer pair combination was calculated for the hunted herd (n=88) and for the sharpshot herd (n=153) to determine social affiliations. Increased social interactions were witnessed for only sharpshot female-female (F5=3.2, p<0.01) and female-male (F5=2.3, p<0.05) combinations post-shoot. Deer shifted out of pre-shoot ranges to become more social (F4=2.0, p<0.10, α=0.10). There were no differences in social interactions post-hunt. Results show that previous reports of geographically rigid home ranges under reduced density underestimated the influence of the matrilineal social network in terms of site fidelity. ^ To assess increased susceptibility to vehicle collisions, home ranges were estimated during hunting, 1-month, and 1-year post-hunt. Road mileage contained within home ranges was calculated. Mean 1-hour movements, movements by time of day, and daily road crossings were determined. Home ranges were larger during hunting (F2,38=10.4, p<0.001). Home range size was positively correlated with road mileage contained within (r1,41=0.94, p<0.001) for the three intervals combined. Mean 1-hour movements increased and deer became more nocturnal during hunting. Daily road crossings did not increase during hunting. While hunting temporarily alters behavioral patterns, it does not increase the chances of deer being involved in vehicle collisions as increased home range sizes and movements did not increase road crossing frequency. ^

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