A contraceptive vaccine for elephants is ready to be introduced in South Africa's major reserves to prevent overpopulation and habitat destruction, scientists have said this week.
Researchers who have been testing the vaccine for the past 16 years said it had proved "between 95% and 100%" successful in 14 elephant populations across the country and was preferable to culling.
Trials on the first wild population in a state reserve, the Tembe Elephant Park in northern KwaZulu-Natal, had resulted in a significant drop in their birth rate since 2007, said Ezemvelo-KZN Wildlife ecologist Catharine Hanekom.
"The aim at Tembe is to slow the increase in the elephant population to reduce the impact on the sand-forest vegetation while awaiting the expansion of the reserve as part of a transfrontier conservation area," she said. "We applied a blanket approach to all female elephants of breeding age and have seen a decline in the number of calves born each year."
The research at Tembe showed the technique was "a viable option for other reserves" concerned about the impact of elephants on biodiversity.
A management tool
"It is important to note that, according to the 2008 national norms for the management of elephant populations in South Africa, contraception must be explored as a management tool before more severe tools," Hanekom said.
South African National Parks said it was poised to test the vaccine in small national reserves, but was not yet ready to try the contraceptive in the Kruger National Park, home to about 14270 of South Africa's 18 000 elephants. Trials would soon start in Marakele National Park and sections of the Addo Elephant National Park.
"SANParks is planning to use contraception in concert with local disturbance activities [such as noise and fencing] to ensure variability in how elephants use landscapes and interact with people, thereby mitigating the effects they may have, particularly in small parks," said spokesperson Paul Daphne.
Since SANParks stopped culling in 1995, it has observed a stabilisation of elephant numbers in the Kruger Park, he said. This was largely because of the closure of watering holes, which had resulted in reduced pregnancies and the natural die-off of four-to eight-year-old calves.
"In the mid-1990s, the growth rate was 6.5% a year, but in the past five years the elephant population has grown at 2.4% a year and that growth is decreasing over time," Daphne said. The average birth rate has decreased from one calf per elephant cow every 3.5 years to a calf every 4.2 years in 2010.
Elephant ecologist Audrey Delsink pioneered research on elephant contraception at Makalali Private Game Reserve in Limpopo 16 years ago. She said the trials in private reserves had "resulted in a robust body of scientific work demonstrating that the technique is an effective way to control elephant population growth".
The next logical step, she said, would be the application of the vaccine in larger elephant populations in national parks. "There is nothing about larger populations that changes the scientific basis or efficacy of the technique. Application to larger populations simply requires an increase in human effort and financial support."
Delsink said the research had shown that the vaccine, called PZP immunocontraception, did not change the animals' behaviour, was reversible if treatment was discontinued and did not result in permanent sterilisation of elephant cows.
Veterinary scientist Professor Henk Bertschinger, who manufactures the PZP vaccine at Onderstepoort, said it stimulated an antibody response that blocked sperm penetration into the egg. Administered by dart, the vaccine requires annual booster shots, but he expected a one-shot vaccine to be available in about two years.
A United States-based non-governmental organisation, Humane Society International, paid R75000 towards the Tembe project last year and has undertaken to help to fund the roll-out of contraception in other reserves run by Ezemvelo-KZN Wildlife, such as the Isimangaliso Wetland Park and Hluhluwe-iMfolozi. The vaccine costs R1138 per elephant, including helicopter flying time and veterinary fees. The NGO's wildlife director, Teresa Telecky, said it was funding research into a vaccine that would last for two or more years.