Wild Elephants in Africa Vasectomized to Control Overpopulation: Colorado State Veterinarian Leads Surgical Team

A Colorado State University veterinarian is leading surgeries with a team of experts performing vasectomies on wild elephants in parks and land reserves in South Africa to curb the need for culling entire families of the species.

Once teetering on the edge of extinction, conservation efforts have been so effective that African officials say many areas are overpopulated by thousands of elephants, a rate of overpopulation that threatens the biodiversity, habitat and success of other species. For example, Kruger National Park alone has too many elephants – 7,000 too many.

     Dr. Dean Hendrickson, a surgeon with a focus on equine medicine, including minimally invasive surgery, and pain relief in Colorado State University’s College of Veterinary Medicine and Biomedical Sciences, has embarked on a series of trips to South Africa to develop techniques for laparoscopic vasectomies in elephants and perform surgeries on mature male elephants. In addition to the sheer challenge of operating on such large and wild animals – a task that includes tranquilizer darts and truck-mounted cranes just to get the animal positioned, the job is further complicated by the relatively little information available about bull elephant reproductive systems.

     "The male reproductive system of elephants has been a largely disregarded in research fields," said Hendrickson. "In fact, the main research paper that exists on the bull’s reproductive system was written in the late 1800s – meaning that the best information we had was 100 years old and not very detailed. We had to start this task by figuring out the anatomy, then figuring out if and how we could successfully perform the surgeries."

     Hendrickson added that, as a species, elephants typically don’t respond well to surgery and anesthesia. However, the doctors wanted to improve the two current methods of population control: culling entire families of elephants or the difficult method of giving an annual shot of birth control to thousands of female elephants via a dart gun from a helicopter. The key was in finding a way to control birth rates through the males in the herd.

     "Information suggests that the dominate male in the herd tends to impregnate the majority of females in the herd," said Hendrickson. "In fact, it is estimated that they impregnate about 90 percent of the female elephants. By impacting specifically the dominate bull’s fertility, we hope to significantly reduce the birth rate in the herd."

     Hendrickson and a team of zoological veterinarians from across the nation visited South Africa early this year on a fact-finding mission that included studying the anatomy of culled male elephants.

     After performing mock surgeries on some culled bulls, the team performed operations on live bulls within herds. The dominant bulls in a few small herds are identified from helicopters, then herded by the air to a location near a road, where the bull is tranquilized with a dart gun from the air. Once the bull is asleep, it must be positioned for surgery by a truck-mounted crane and heavy-duty straps. The surgery is performed on both sides of the large animal’s reproductive system. The elephant is positioned comfortably on the ground and the crew drives away to watch it wake and recover from a distance.

     The surgery is performed through three small incisions, one about four inches in length, and a one-inch incision on each side of the animal. The small size of the incision minimizes the risk for infection as the animal recovers in its natural habitat. The team uses equipment specially designed for the surgeries they will perform — the only equipment of its kind in the world.

     Key to the effectiveness of the vasectomy tactic, said Hendrickson, is an understanding of the societal fabric of elephants. Operating on the dominate bull significantly impacts the population of a herd, while allowing for a low birth rate and the continuation of the social structure of the herd. Elephants travel in groups of 15 to 20 females and young which are ruled by a matriarch and dominate bull. In general, the matriarch, other females and young elephants stay in a group and the dominate bull roams close to the herd. "Satellite" bulls, or bulls that are not dominate, perhaps because they are young, surround the herd from a distance. Although the dominate bull impregnates the vast majority of cows, the satellite bulls engage in "sneak breeding," and father a small number of calves in each herd. The fertility of the dominate bull does not appear to affect his status, and he typically remains in command until he dies. Then, the satellite bulls vie for power.

     "It also is important that elephants be understood as a family unit," said Hendrickson. "We know that if only random elephants are culled from a family, the younger elephants left behind suffer from the loss of their role model and, basically, engage in juvenile delinquent behavior. They become aggressive toward other animals and destroy their habitat or starve to death because they don’t know how to survive on their own. Elephants move and work together as a family. If officials feel it is necessary to cull elephants, they must cull an entire family, including the young."

     Hendrickson added that the entire body of a culled elephant is used by the local population. In addition to eating the meat, they use the bones for tools.

     Hendrickson is the only non-zoological veterinarian on the team, which includes two veterinarians from South Africa and several doctors from the United States. The veterinarians on the team include Dr. Mark Stetter from Disney’s animal kingdom, Dr. Jeff Zuba from San Diego Wild Animal Park, and Dr. Douw Grobler from Catchco South Africa.

     The group will return to South Africa this summer to perform more surgeries. The gestation period for elephants is 22 months, so they will be unable to gauge the effectiveness of the vasectomies they’ve performed for another two years.