Elephant contraception

The elephant contraception was done before the Annual Aerial Game Count because the presence of the helicopter does affect the movement of the elephant within the Reserve which makes locating them more difficult if the helicopter has already disturbed them.
The elephants are then generally left as undisturbed as possible during the game count.

The Reserve Research Ecologist is trying to quantify this disturbance by making use of the GPS collar data that is available for two of the herds. Unfortunately to be scientifically sound a number of years of data is required. We eagerly await the results.

The contraception entails darting all the elephant cows that are potentially able to reproduce i.e. all female animals older than about 9 years old. Each cow is darted using a fall out dart that carries the immune-contraceptive pZP (porcine zona pellucida). The pZP works by blocking the sperm receptor sites on the ovulated eggs, thus forming a physical barrier between the sperm and egg. Hence, the vaccine is not only highly effective but is also safe and reversible when annual re-vaccinations are stopped.

The contraception program was initiated in 2005 as part of a large scale research program to determine the efficacy of contraception but specifically to determine if there were any behavioural abnormalities. For 3 years after the initial contraception the elephant’s behaviour was monitored on a near permanent basis. All this behavioural as well as movement data of 2 GPS collared animals together with the data from numerous other reserves has recently been written up and published.

No concerning abnormal behaviour was observed in the elephant populations of any of the reserves participating in this research program under the guidance of Prof Henk Bertschinger from Onderstepoort and PhD student, Audrey Delsink, from the University of KwaZulu-Natal.

Due to the long gestation period for elephant, 22 months, it was 2007 before there were no more calving incidences on Welgevonden and this remained so until Reserve management deliberately did not immunize an adult cow from each herd.

This was to allow all the herds to have the presence of a small calf in them. After all what would a herd of elephant be without a small calf around! Calves are an integral part of the herd and social structure of elephants. Already 2 small calves have been born. It must be remembered that contracepting 58 elephant cows in field conditions is not a perfect science and a calf was born to one of the “other” females.

The potential reason that she fell pregnant could be that the animal was away from the herd at the time of contraception, a failed dart or that the animal was missed. The aim of Welgevonden is not to stop all breeding of elephant but to slow down the reproductive rate therefore “buying” time to find relocation opportunities or increase the Reserve’s size.

This year 62 elephant females were contracepted.