Putting elephants on the Pill

Ex-QDMS

SA has about 18 000 elephants, mostly in the Kruger National Park, out of southern Africas 280 000 elephants. Botswana has the largest population, about 134 000, followed by Zimbabwe with about 84 000.

Cooped up behind a wall of fences and human obstacles, Africa’s elephants have become ever more dependent on the will of man to determine whether they live or die – or get to breed. There are some herds that still enjoy a limited degree of freedom in parts of the continent, but most SA elephants are now trapped within the finite boundaries of national and provincial parks.

It is only a matter of time before their population levels reach saturation point.

At some point, their numbers will reach levels which force wildlife managers to reduce their numbers, or reduce their growth rate.

In the Kruger National Park, almost 17 000 elephants were shot between 1967 and 1995, when a moratorium on culling was put in place.

But in 2008, the government reopened the door to culling as the option of last resort to manage the inevitable increase in the park’s elephant population.

Other options have included shifting elephants to other parks, or indirect methods such as reducing the number of artificial waterholes. But this is unlikely to offer much relief in the long term.

The PZP vaccine, which is extracted from the outer layer of pig eggs, has been found to block reproduction by preventing sperm from penetrating mammal eggs.

Hunting or sterilisation could also work, but these options raise a whole set of ethical and political problems.

This has made contraception an increasingly attractive option for several elephant managers, especially in smaller reserves where it is easier to identify individual elephant cows on a yearly basis.

The conundrum of how to control elephant populations was just one of the issues facing ecologists and wildlife managers from 40 countries who gathered in Durban last week at the International Wildlife Management Congress.

Among the delegates were a group of researchers involved in an ambitious elephant contraception project funded by the Humane Society International.

The researchers have been busy for 15 years and believe they have demonstrated that immuno-contraception is a serious and effective technique to control elephant population growth.

Their conclusions are based on the results of “vaccinating” hundreds of elephant cows in 14 SA game reserves with a non-hormonal contraceptive developed from pig eggs.

Known as porcine zona pellucida (PZP), the contraceptive technique is based on the same principle as disease prevention through vaccination.

The first PZP birth control experiments were done on wild horses on a US island and have also been used on deer, buffalo and other mammals in several parts of the world.

In SA, the first PZP experiments began on elephants in the Kruger National Park in 1996, with field trials showing success rates of 56-80 percent, according to Audrey Delsink, an elephant ecologist and field director of the PZP project.

Since then, the project has been refined to the point where PZP has demonstrated an effectiveness of between 95 percent and 100 percent in preventing elephant pregnancies.

In KwaZulu-Natal, the vaccine is also being used to control elephant numbers in the Tembe Elephant Park, along with the Phinda-Munyawana and Thanda private game reserves. The Tembe elephant population has risen from about 80 animals in 1983 to more than 250 today, putting increasing strain on the park’s rare sand forest.

Delsink says the vaccine has also been used in Makalali private game reserve in Limpopo for the past 12 years to limit the total population to about 70 animals.

Makalali warden Ross Kettles has described the PZP project as a “resounding success” as well as the “least invasive and most humane” population control method. In this reserve, the vaccine is only injected after cows have borne at least one calf.

Delsink says one of the major advantages of PZP is that the contraception is fully reversible if the treatment is discontinued, and does not result in permanent sterilisation of elephant cows. “After 16 years of investigation there has been no empirical data of harmful behavioural effects,” she told the congress.

One of biggest drawbacks is the current cost of treating cows on a regular basis. To administer the vaccine, the PZP contraceptive is shot into the animals’ rumps using a dart gun, either from the ground or from a helicopter.

Laboratory project head Prof Henk Bertschinger of the University of Pretoria says animals have to be darted three times during the first year (a primary vaccination followed by two booster shots).

Thereafter, a single booster is needed every year to maintain the contraceptive effect – although a new one-stop inoculation is being developed to reduce the number of dartings.

JJ van Altena, who manages the PZP darting project, believes that contraception for much larger elephant groups is now “definitely in reach”, especially with the development of a longer-lasting vaccination.

All the same, managing a contraceptive programme in a 2 million hectare park such as Kruger could be hugely expensive and present major logistical challenges in darting up to 5 000 elephant cows every year.

At the moment, the first year of treatment alone stands at somewhere around R800-R1 500 per animal (much of which is made up of helicopter costs but could be reduced significantly for large oganisations like SanParks which have their own helicopters and crews).

Pilot trials were conducted in Kruger from 1996-2000, but SanParks managers still appear wary about rolling out PZP on a large scale.

Eight years ago, SanParks came up with a rough estimate of R1.4m a year to administer PZP to 75 percent of the breeding cows in Kruger, noting that similar costs could be expected every year thereafter.

“It is not even certain that such an exercise, due to its complexity, is logistically feasible,” a senior SanParks researcher said at the time.

From a financial perspective, cash-strapped park managers might also find it more profitable to return to the old policy of culling elephants.

A separate study in Kruger almost a decade ago suggested that SanParks could raise at least R5.2m profit from selling the meat and skins alone from 800 culled elephants a year.

This excludes potentially much larger profits from selling elephant ivory (which is still largely banned, with the exception of occasional one-off sales).