20 Nov Effective Contraceptive
Reading time: 5 minutes
Intense concentration stifles the room. The four young gentlemen carefully mixing contraceptive drugs have been warned that a single drop of the solution in their blood stream will lead to sterility. Not an appealing thought. But the porcine Zona Pellucida, or pZP, will do no harm to elephants – merely prevent pregnancies.
The Complexities of Population Control
Elephants are intelligent and empathetic creatures. They are capable of expressing a wide range of human-like emotions such as empathy, joy, sadness and concern and even symptoms of post-traumatic stress disorder (PTSD) after having been exposed to severe tragedy. But their complex nature, although impressive, contributes towards the difficulty of their management, especially when it comes to population control.
Elephants are known as what’s called a “keystone species” – they transform their savanna habitat and influence ecosystem function. These animals open up the landscape by tearing down trees which improves environmental conditions for certain species and maintains a particular habitat structure. Unfortunately, where population size is left unchecked (particularly in small and medium sized reserves) their influence on the vegetative composition can turn into that of a destructive nature. For example, by trampling plants and uprooting trees as they feed, elephants are capable of rapidly reducing large forests into grassland. The concern is that this could eliminate certain species from the ecosystem. If conservation managers wish to maintain high levels of diversity and protect a wide range of species rather than only a select few, they need to manage and monitor their elephant population intensively. Naturally, population size is the most crucial factor in elephant management. And the most controversial.
Historically, culling was the predominant method used in regulating elephant population size. The practice goes about removing entire breeding herds so as to avoid the stress of family members left alive. Aside from this scenario being seldom achieved, this management technique is considered inhumane and is hardly applicable to small populations of elephants. With increasing public pressure regarding the ethics of procedure, elephant culling was officially banned in 1995.
Although a step in the right direction, park managers were now faced with a new challenge: elephant numbers were climbing out of control. Between the initiation of the ban and 2008, the national population had grown from 8 000 to over 20 000 individuals leading to fears of unsustainable population growth within fenced reserves. During this period, managers made use of translocation as a means of population control, but opportunities to do so were (and still are) extremely rare. The only other option to manage elephants, other than to expand the size of reserves, was to decrease reproductive success through contraception – an option that was not available at the time.
A Solution Emerges
In 1999, researchers confirmed that the porcine Zona Pellucida (or pZP) vaccine could be used as a tool to protect elephant cows against conception. The highly versatile immuno-contraceptive molecule, which has been tested on everything from stray cats to voles to elephants, promotes the production of antibodies that bind to ZP proteins of the target animal’s oocytes, preventing sperm binding, fertilisation and in turn, pregnancy. Contrast to hormonal contraceptives, the vaccine is efficient, reversible, safe, remotely deliverable, and has minimal impact on the social behaviour of elephants.
This was ground breaking research – the first safe method of sterilizing free-roaming African elephants had finally emerged (and was even published in renowned scientific journal, Nature, in 2001).
Practical application of this contraceptive method was initiated in 2005 where 7 different private game reserves (including Welgevonden) opted to adopt the revolutionary science and incorporate it into their management strategy. Over the course of the next 9 years, a total of 108 individually identified cows were treated and monitored so as to evaluate the effect of the vaccine on both reproductive rate and the safety of the cow during pregnancy. This large-scale research showed that the vaccine was highly effective as a birth control mechanism: 100% safe for conceptuses at any stage of development, delivery is remote and does not require animals to be immobilized, 100% effective, and sufficient in achieving a population growth rate of 0%.
“The use of pZP has provided small-medium sized reserve managers with the opportunity to maintain a viable population with minimal impact on reserve biodiversity without sacrificing all important game viewing opportunities”, says Matthew Thorp, Welgevonden Elephant Monitor. “While the management of elephants is a contentious topic at the best of times it is of utmost importance that interventions are carried out as ethically as possible.”
Since its initiation in 2005, elephant contraception with the pZP vaccine has become an integral component of elephant management at Welgevonden Game Reserve. The initial process involved a primary vaccination, administered to elephant cows that were 10 years and older, followed by two boosters at 3-4 week intervals. The elephant cows have received a single booster per annum ever since.
“At WGR, with the pZP being an annual occurrence, the implementation thereof can be likened to that of a well-oiled machine with the resultant disturbance being mitigated at every possible turn”, says Matthew.
The vaccine is aerially administered – each cow is darted from the helicopter with a biodegradable dart that falls out once the immune-contraceptive has injected into the bloodstream. To ensure that no cows receive a double dose of the drug, a purple dye sprays out the back of the dart upon injection, lathering a portion of the buttocks with a purple hue and clearly marking the elephant as “darted”. This dye is perfectly safe and easily washes off after a few days.
But What About Herd Dynamics?
The vaccine does not halt population growth immediately. With some of the cows already pregnant and a gestation period of 22 months, populations will take up to three years before stabilizing. If desired, it would be possible to completely inhibit births from this point onward provided that all reproductive cows had received the contraceptive. But a birth rate of 0% is not something management wish to achieve. Calves play an important role in “elephant society” in that they are integral to herd cohesion. In fact, family groups are known to branch off into smaller and smaller herds where calves are excluded from the population – unnatural behaviour for such a socially complex species. For this reason, certain individuals are deliberately “skipped” during contraception, ensuring that calves are still born into the population.
“We try to keep the herd dynamics of our elephants as natural as possible”, says Matthew
2018 Contraception Intervention
This year, the annual contraception kicked off on the 14th of September. The exciting procedure started with a number of our staff, under the careful guidance of Dr. Peter Caldwell, assisting in preparing the contraceptive solution (que back to the stifling concentration). 75 darts were prepared for the purpose of the procedure after which Matthew, Samuel Davidson-Phillips, Dr. Peter Caldwell and pilot, Lambert van der Westhuizen, took to the skies in a sleek Squirrel helicopter. With the location of each herd predetermined (thanks to the GPS coordinates transmitted from the collars deployed on the 7 different matriarchs) the group set out with purpose. And a 2 hour time cap. Thankfully, the procedure ran smoothly and the team easily located each herd, darting a total of 60 different individuals in under 1 hour and 40 minutes.
“It was exhilarating to be part of the contraception operation this year. Fast paced, accurate and efficient, the small team worked well together to locate, identify, and dart the various cows”, says Matthew. “Flying above the population of elephants, a population that I have come to know more intimately than most, I am reminded of the importance of constantly pushing management boundaries to create the most hospitable environment in which elephants may flourish.”