E-Insight

August 2005

Colorado State Veterinarian Leads Surgical Team Working to Control Elephant Population in South Africa

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 7,000 more elephants than the land can support.

Dr. Dean Hendrickson, an Associate Professor in the Department of Clinical Sciences and a veterinary surgeon with a focus on equine medicine, including minimally invasive surgery, and pain relief, 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 Dr. 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."

Dr. 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 bull in a few small herds was identified from helicopters, and then herded by the air to a location near a road, where the bull was tranquilized with a dart gun from the air. Once asleep, the bull was positioned for surgery by a truck-mounted crane and heavy-duty straps.

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 perform -- the only equipment of its kind in the world.

Key to the effectiveness of the vasectomy tactic, said Dr. 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 dominant bull. In general, the matriarch, other females and young elephants stay in a group and the dominant bull roams close to the herd. "Satellite" bulls, or bulls that are not dominant, perhaps because they are young, surround the herd from a distance. Although the dominant 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 dominant 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 Dr. 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."

Dr. 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.

Dr. Hendrickson is the only non-zoological veterinarian on the team, which includes two veterinarians from South Africa and several doctors from the United States. 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.