National Wildlife Research Center (NWRC) |
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Development of Reproductive Control Methods for Overabundant Birds
and Mammals
| PROJECT GOALS: To obtain U.S. Environmental Protection Agency approval for use of PZP and GnRH immunocontraceptive vaccines for white-tailed deer and to develop new oral contraceptive agents for use in controlling reproduction in overabundant avian species such as monk parakeets and crows and in mammalian species such as California ground squirrels and prairie dogs. Project Accomplishments 2008 Squirrel Contraceptive Research at Clemson University—NWRC is collaborating with Clemson University to test a new gray squirrel contraceptive on campus. The lack of predators in the urban area has allowed squirrel numbers to increase and and cause significant damage to trees and shrubs by gnawing and stripping bark. The Clemson campus landscape crews have documented more than 100 mature trees killed by squirrels, with an additional 100 trees severely damaged.The study is evaluating the effectiveness of the contraceptive GonaCon, which is injected into both male and female squirrels and cause infertility after just one treatment. About 40 squirrels have been trapped, tagged, injected with GonaCon and released. Another 40 squirrels have been trapped, tagged and then released as a control group. The health, sex and age range of each animal will be recorded and their reproduction rate monitored next spring. Prairie Dog Contraception—Prairie dog colonies across the Front Range of Colorado, have expanded to the point that they have denuded the landscape, particularly suburban settings. Conflicts about how to manage prairie dog colonies in urban areas have become more common between resource managers who must manage natural areas to maintain native plant life and residents who oppose lethal control of colonies. In October 2006, NWRC scientists initiated a study in Larimer County, CO, to evaluate the feasibility of using GonaCon™ as a nonlethal management tool for black-tailed prairie dogs in urban and suburban settings. Prairie dogs were captured on control and treatment sites, weighed, sexed, and marked with ear tags and fur dye. In addition, each captured prairie dog was vaccinated with either a sham vaccine or GonaCon™. Beginning in May 2007, prairie dogs were recaptured at both sites to determine breeding status and to collect blood samples for analysis of anti-GnRH antibody titers. Pup counts were also conducted during May and June 2007. A second year of data was collected during the summer of 2008 to determine longevity of the vaccine. All treated animals recaptured during the first year were infertile. Only a small percentage of treated animals could be recaptured in 2008. Of the 6 treated animals that had retained eartags, half were still infertile. In addition to the GonaCon™ study, NWRC scientists initiated another study in November 2007 to evaluate DiazaCon™ an oral reproductive inhibitor for prairie dogs. Rolled oats coated with DiazaCon™ and molasses were fed for ten days during November 2007. Pup counts were conducted in June 2008. Preliminary data show a 98% reduction in the numbers of pups per adult. Elk Contraception Tests in Rocky Mountain National Park—Unregulated concentrations of elk have become a significant problem for resource managers in Rocky Mountain National Park (RMNP). An NWRC scientist is collaborating with researchers from Colorado State University on a 3-yeasr study to evaluate the the efficacy and safety of the immunocontraceptive vaccine GonaCon™ as a potential management tool for reducing populations and controlling reproduction of free-ranging female elk in RMNP. One hundred and twenty elk (60 treated with GonConTM: 60 control) were captured and radiocollared during January of 2008. Beginning in January 2009, 40 elk (20 treated:20 control) will be recaptured and euthanized each year for next three years to evaluate the effective duration of GonaConTM on elk reproduction. Postmortem examination of the reproductive tract of each animal will be conducted at CSU’s Veterinary Diagnostic Laboratory in Fort Collins, Colorado. Project
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Last Modified: June 8, 2009