Control of reproduction in overabundant white-tailed deer populations
Abstract
I investigated techniques for capturing white-tailed deer, a contraceptive delivery system, and the efficacy of 2 reproductive inhibitors. I compared concentrations of blood serum cortisol, as an index of stress, under 2 different techniques for capturing white-tailed deer. Mean cortisol concentrations were lower in animals captured using darts (11.6 ng/ml) than in those captured with drop nets (60.5 ng/ml) $(P < 0.05).$ Cortisol concentrations under both capture techniques were greater than baseline levels (4.1 ng/ml) $(P < 0.05).$ My results demonstrate that remote immobilization produces less stress and is nearly as efficient as capture with drop nets. I also conducted field and laboratory trials to evaluate the utility of a new biobullet delivery system to administer contraceptive agents. During field trials on white-tailed deer, I determined the terminal velocity necessary to achieve acceptable biobullet delivery (480 ft/sec). Laboratory calibration trials were used to establish the pressure settings of the delivery system required to obtain acceptable penetration at a given distance. After determining the appropriate biobullet terminal velocity for a particular species, pressure settings can be calculated for delivery at a selected distance. Finally, I tested the steroidal compound norgestomet (42, 28, 21, 14 mg) and prostaglandin F$\sb{2\alpha}$ during 1992-95. Does were captured, ear tagged, and subsequently treated via remote delivery using biobullets. Both agents reduced fertility significantly relative to untreated control animals. Effectiveness of norgestomet implants in preventing pregnancy was similar for the 42 mg (92%), 28 mg (100%), and 21 mg (100%) doses. There was a significant decline in efficacy using the 14 mg (48%) dose. Prostaglandin caused pregnancy termination in 88% of treated does. Reproductive inhibitors show promise for use as a deer management option in small, isolated environments.
Degree
Ph.D.
Advisors
Swihart, Purdue University.
Subject Area
Forestry
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