Maintaining a
functioning ecosystem
functioning ecosystem
Elephant management has and will always be an emotive subject. The newly published National Norms and Standard for elephant management highlights just this. However, it is a subject that any reserve that has elephants will face sooner or later, even more so for small reserves. On Welgevonden this is no different and we have adopted an active elephant management program over the last few years.
The objectives of elephant management on Welgevonden are to
Maintain a demographically viable population
Maintain a functioning ecosystem
Control the number & growth rate of elephant
Contribute to an understanding of biology and management of elephants
Contribute to the conservation of elephants
Elephant populations are known to double every ten years, and this obviously represents a considerable risk for biodiversity conservation as a result of the cumulative impact on vegetation composition and structure over time. In order to achieve the objectives of the elephant management plan, Welgevonden is continuously exploring possibilities for translocation and elephant have been translocated to the Eastern Cape in the past.
Unfortunately, possibilities for translocation are limited, and to slow down the population growth rate an immunocontraception program was initiated in 2005 to reduce the birth rate. The contraceptive vaccine (porcine zona pellucida, or 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.
Application does not require the cows to be immobilised as the vaccination is simply applied using drop-out darts delivered from a helicopter. The vaccination protocol entails a primary vaccination followed by two boosters at 3-4 week intervals during the first year and a single annual booster thereafter. Taking existing pregnancies into account (which are not affected by the vaccine), stabilisation of the population occurs after approximately three years. The population on Welgevonden stabilized by September 2007 but since then some cows have been deliberately “skipped” during the contraception to allow a limited births within the herds. After all what is an elephant herd without calves which are an integral part of elephant society!
When the contraception program started the use of pZP contraception as a mechanism to manage elephant populations in small reserves was a reasonably recent development and therefore limited data on the long-term responses of the elephant population in terms of social behaviour was available. Consequently, Welgevonden was in a position to play an important role in advancing research on contraception as a means to control elephant numbers in small, confined reserves. A dedicated elephant monitoring programme was established to closely monitor the impact of the contraception program on the population. To date, no changes in social behaviour have been recorded.
Given the ecological requirements for flux within an ecosystem, an elephant population should not be allowed to remain at a constant level over an extended period of time. The challenge is to identify upper and lower limits of acceptable change and manage the population within these limits. The need to reduce numbers from time to time infers that relocation and/or culling of elephants in confined reserves will continue to be necessary, but contraception will enable management to better control the frequency and extent of such interventions
As part of our commitment to enhance research on elephant management, Welgevonden became the first reserve where a completely successful laparoscopic vasectomy on an elephant bull was performed in 2006. Although it was performed before on elephants elsewhere, it was previously only done on one side, or other complications were encountered.
A research team from the USA did 4 successful vasectomies on 4 different bulls in 4 days on Welgevonden. This was done as part of a research program on laparoscopic vasectomies on elephant bulls in an attempt to find alternative population control measures for small populations of elephants on small reserves. The research is a joint program run and funded by Disney’s Wildlife Conservation Fund and the Zoological Society of San Diego. The research is still very much in an experimental phase, and techniques are still being developed, but the progress made on Welgevonden will be very valuable in the future. However, the research promises to offer a good alternative tool in the toolbox of elephant management actions in the future.
