Immuno-Contraception Research for Managing Tule Elk Population - Phase I Scheduled to Begin on August 6, 1997

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Date: August 5, 1997
Contact: John Dell'Osso, 415-464-5135
Contact: Kim Dreyfuss, 415-669-7340

Superintendent Don Neubacher today announced the first phase of an immuno-contraceptive research project will begin on August 6 and 7 at Point Reyes National Seashore. The research will be conducted by National Park Service, California Department of Fish and Game, and UC Davis and will evaluate the effects of implementing a fertility control program to manage the size of the tule elk population inhabiting Point Reyes National Seashore. This research will provide valuable information to park management and guide future decisions related to elk management.

Research on immuno-contraception will determine whether this option can be used effectively to control the elk population at Point Reyes National Seashore. Other research will determine potential impacts of elk grazing on the overall range and to other threatened and endangered species.

Immuno-contraception is a form of vaccine contraception administered to female elk which stimulates the immune system to produce antibodies that block sperm from attaching to the ovum. Fertilization is prevented by a glycoprotein-based vaccine which would not interfere with pregnancies in progress, or with established social organization and behavior. This method poses little physical risk to the animals.

The use of a contraceptive vaccine based on the porcine zona pellucida (PZP) has been successful in inhibiting reproduction in wild horses, white-tailed deer, and numerous captive exotic species. Currently, this technology is being applied to other free-ranging species, including feral donkeys, African elephants, water buffalo, and more than 95 species of captive exotic animals.

During the contraceptive research project, the first vaccine will be administered by direct syringe injection. To administer the injection, 30 elk will be netted from a helicopter net gun and hobbled by ground crews. Scientists will gather data on the individual elk and place a radio collar on each of the elk. The collar will allow scientists to follow the individual elk to determine the effectiveness of the contraceptive. After several weeks, a booster shot will be remotely administered, from ranges of 30 to 150 feet, by means of self-injecting darts. The darts are brightly colored and easily retrieved. A single annual booster inoculation will be administered to continue contraceptive effects for successive breeding seasons.

Because of the use of helicopters, the Tomales Point Tule Elk Range will be temporarily closed to the public. This will ensure the safety of both the public and the elk. In turn, because the area is Congressionally-authorized wilderness, the area is closed to all other aircraft.

Funding for tule elk projects has come from a variety of sources. To date, monetary support and in-kind services for the tule elk project has been received from the Rocky Mountain Elk Foundation, Point Reyes National Seashore Association, Committee for the Preservation of Tule Elk, California Department of Fish and Game, The Humane Society of the United States (HSUS), University of California at Davis, the National Park Service Natural Resource Preservation Program and In Defense of Animals.

Over the next year, Point Reyes National Seashore and the California Department of Fish and Game will be preparing a draft tule elk management plan and environmental analysis for public review. From the draft document, the park will prepare a final management plan to guide future management decisions for tule elk on Tomales Point and other locations if determined appropriate. For the last three years, research has been conducted to obtain critical data on populations dynamics, herd composition and size, and the condition of the plant communities on Tomales Point. Research has also been conducted to ascertain the potential impacts of tule elk grazing on special status species. From this critical research and public input, the final management plan will be developed to ensure long-term protection for the elk and the environment of Tomales Point.

Tule elk were reintroduced to Point Reyes National Seashore on Tomales Point in the spring of 1978 with two bulls and eight cows translocated from the San Luis Island National Wildlife Refuge near Los Banos, California. The elk were released on 2,600 acres within a fenced area of open grassland and coastal scrub, withdrawn from cattle grazing and designated as legislated wilderness. Initially, tule elk population growth was low; the herd increased at a steady annual rate of about 15 percent. This rate of growth remained constant throughout a period of sustained drought during the mid and late 1980s. By the summer of 1988, the population was at 93 animals. Their numbers continued to increase: 169 elk were counted in 1991, 240 in 1993, and 254 in 1994. Following the end of the drought in the early 1990s, range condition improved dramatically with a consequent rapid increase in elk numbers. The population census taken in the fall of 1996 counted 386 elk (approximately 90 calves)--a 33% increase from the prior year. In the spring of 1997, 92 calves were born. In turn, the herd suffered 13 moralities by natural causes. Current Point Reyes herd size is 465; 18% of the state population.

Since 1971, the Department of Fish and Game has captured and moved more than 900 tule elk to reestablish herds in suitable historic habitat. The statewide tule elk population has increased from approximately 500 animals in three herds in 1970 to more than 2,700 animals in 22 separate herds today. At one time, a half million elk roamed California's mountains, valleys and coastal forests; by 1860 only two small herds remained.


Last updated: February 28, 2015

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