A Humane Approach to Elephant Population Control

Despite the continued presence of poaching in parts of Africa, elephant populations are growing at rates of 4 to 5 percent in some regions of the continent. At the same time, a decline in elephant habitat, given over to an expanding human population and an increased agricultural presence, has led to human-elephant conflicts, degradation of habitat and a decreased tolerance for the species in many areas. This has spurred management actions of a lethal nature, and the Kruger National Park in the Republic of South Africa killed between 300 and 800 elephants annually until 1995, in an effort to stabilize the population.

That year, a coalition of scientists from the Science and Conservation Center, University of Georgia, University of Pretoria and Kruger embarked on a project to test the concept of immunocontraception in Kruger's elephants, since it had been so successful in the United States with wild horses, urban deer and zoo animals. While there was an undercurrent that contraception was not liked by many locals because of its cost and the fact that it was being pushed by foreigners, there was enough support to conduct the study.

Twenty-nine adult female elephants were captured by immobilization between Oct. 1996 and 2000, then tested for pregnancy by ultrasound, fitted with radio collars and given an initial inoculation of the contraceptive vaccine porcine zona pellucida (PZP). Booster inoculations were given without capture, by a dart from a helicopter. The treated elephants could then be followed over several years.

The results demonstrated the PZP vaccine is highly effective in inhibiting fertility, that it is reversible in its contraceptive actions because it requires annual booster inoculations, that it is safe to give to pregnant and nursing animals and that no debilitating health side effects result from treatment. Ultrasound examination of the reproductive tract indicated the ovaries continue to look healthy and function properly and the uterus of the treated animals remains normal. It was clear by 2000 that contraception was in fact a reasonable approach to the humane management of elephants.

One of the few remaining questions centered on the possibility that fertility control and a plethora of non-pregnant animals would change the complex social behaviors and structures of elephant society. Unfortunately, Kruger is not a good place to study behavior because of the dense bushveldt in which the animals live.

The Makalali Experience

Makalali, a private game park in South Africa, requested the research team begin long-term studies on its grounds as the Kruger project neared completion. This park had about 60 elephants on limited land and its officials didn't want many more animals. At the same time, it was not interested in pursuing lethal controls because of opposition from the public. In this long-term study, the formulation and doses of the vaccine were altered, treatment was remote and the focus of the study was on behavior.

This study is ongoing and is entering its fifth year, but already a number of important discoveries have been made. First, the change in formulation of the vaccine led to a 100 percent efficacy in contraception, as opposed to the 75 percent efficacy achieved at Kruger. Second, it was revealed that smaller doses can bring about contraception, which has reduced the cost. The study has also confirmed the earlier discoveries that the vaccine was safe to give to pregnant animals. No behavioral consequences have yet been discovered, except that animals became more wary of the darters. The PZP vaccine does not inhibit estrous cycles, but bulls did not harass treated females over the course of the study. Perhaps most importantly, it was demonstrated that fertility control could manage an entire population, and growth of this herd has stopped. None of the 350 elephants we treated died in this study.

The success at Makalali led to enthusiasm from a number of game reserves throughout South Africa, and the demand for vaccine increased to the point that the Science and Conservation Center was unable to provide the large quantities needed and still meet the domestic demands for wild horses, zoo animals and deer in the United States. This phenomenon led to the third phase of the elephant contraceptive program.

Technology Transfer

From the beginning of this project in 1995, it was made clear that the elephant "problem" was an African problem, and the involvement of North American scientists was only advisory in nature. Consequently, the grand design of this huge endeavor was to avoid "conservation imperialism" and to teach the Africans to be self-sufficient in the event the project worked. Dr. Henk Bertschinger, a professor of theriogenology at the University of Pretoria, traveled to the Science and Conservation Center in 2003 to be trained to make the PZP vaccine with his lead technician. His group produced enough vaccine by the end of 2003 to treat hundreds of elephants, and at least five game parks have been added to the list of parks managing their elephants with this humane approach.
The remaining task is to overcome resistance from those who prefer culling elephant populations and to turn to the technology of fertility control to keep South Africa's elephant populations healthy and in concert with their habitats. Some may still press for their death, but it is clear that a kinder and gentler approach to managing these magnificent animals does exist.

These projects were made possible with support from the Science and Conservation Center, US Fish and Wildlife Service's African Elephant and Rhino-ceros Conservation Fund and the Humane Society of the United States.

You Can Make a Difference

A South African National Parks official recently told news media culling could soon resume at Kruger as a quick fix to curbing the elephants' population size. Please send letters in support of non-lethal population management to South Africa President Mbeki at:

The Presidency
Private Bag X1000
Pretoria, South Africa 0001

It is worthy to include a footnote that as far back as 1992, the late Christine Stevens, founder of the Animal Welfare Institute, promoted this concept and was a moral force in bringing the idea to the attention of both Africans and the aforementioned research team.

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