Elephant Immunocontraception | Dispelling the Myths

Elephant family.

The issue of elephant management is currently a hot topic as the minister of environmental affairs and tourism, Marthinus van Schalkwyk, has released the Draft Norms and Standards of Elephant Management in South Africa.

Text and pics Audrey Delsink


After commissioning a Scientific Round Table of elephant experts, the minister has ordered an assessment of elephant management in South Africa. More detail is available on the website at www.elephantassessment.co.za.

As part of this assessment, a group of local and international scientists report on an alternative method of elephant population control called Porcine Zona Pellucida (PZP) immunocontraception. This method does not manipulate gender hormones, and is completely different to the way contraception in humans ("the pill") works.

After the initial trials of the immunocontraception in the Kruger National Park (KNP) (1996 – 2000), the team have been studying the follow-up phase at The Greater Makalali Private Game Reserve, outside Hoedspruit, from 2000 until today. 

These studies have spanned approximately 12 years. Unfortunately, the initial hormonal trials run in conjunction with the immunocontraceptive trials in the KNP have incorrectly labelled both methods of elephant contraception as socially disruptive, displaying severe behavioural anomalies.

Whilst this was clearly demonstrated with the hormonal trials, a comprehensive, long-term study at Makalali has revealed that immunocontraception is a safe, reliable, reversible, efficacious means of fertility control with no behavioural anomalies.

In October 2007, the research team immobilised four elephant cows from the Makalali population for the purposes of replacing their radio collars with satellite collars, and for conducting transrectal ultrasonography. The ultrasound would demonstrate the elephant's pregnancy status as well as provide an indication of the animal's reproductive health.

As expected, none of the elephants were pregnant, and no abnormalities were evident in the reproductive tract demonstrating that the medium-term use of PZP does not have any harmful physiological effects. Blood and faecal samples were collected for hormone analysis to determine whether or not the cows had recently cycled.

At Makalali, the occurrence of oestrous is recorded through behavioural observations, and this is subject to observer bias and challenges of the reserve, which could include thick bush, which hampers observations etc. Faecal analysis provides a more objective method to assess oestrous and stress and individual cow cycles can be tracked over time.

This method has been applied at Thornybush Private Game Reserve, where Melodie Bates is conducting her masters degree on ‘Oestrus cyclicity and physiological stress response to immunocontraception in the female African elephant'. Faecal samples from the Makalali population will be collected and added to Melodie's analysis.

The Makalali study has further demonstrated that the vaccination does not affect pregnancies in progress (irrespective of how far along into the pregnancy the mother is) and a non-pregnant female will be immediately contracepted from the first vaccinational series.

Makalali's detailed population history allowed for a predictive model to project population sizes through to 2010 under the current management strategy, which allows young cows to fall pregnant before being contracepted.

This is necessary for the social well-being of the herds and the and for conducting transrectal ultrasonography. The ultrasound would demonstrate the elephant's pregnancy status as well as provide an indication of the animal's reproductive health.

As expected, none of the elephants were pregnant, and no abnormalities were evident in the reproductive tract demonstrating that the medium-term use of PZP does not have any harmful physiological effects. Blood and faecal samples were collected for hormone analysis to determine whether or not the cows had recently cycled.

At Makalali, the occurrence of oestrous is recorded through behavioural observations, and this is subject to observer bias and challenges of the reserve, which could include thick bush, which hampers observations etc. Faecal analysis provides a more objective method to assess oestrous and stress and individual cow cycles can be tracked over time.

This method has been applied at Thornybush Private Game Reserve, where Melodie Bates is conducting her masters degree on 'Oestrus cyclicity and physiological stress response to immunocontraception in the female African elephant'. Faecal samples from the Makalali population will be collected and added to Melodie's analysis.

The Makalali study has further demonstrated that the vaccination does not affect pregnancies in progress (irrespective of how far along into the pregnancy the mother is) and a non-pregnant female will be immediately contracepted from the first vaccinational series.

Makalali's detailed population history allowed for a predictive model to project population sizes through to 2010 under the current management strategy, which allows young cows to fall pregnant before being contracepted.

This is necessary for the social well-being of the herds and the population's demographics. Even under this strategy, the immunocontraceptive will effectively reduce the population growth rate by 70 percent for the period 2003 through 2010. The aims of the Makalali study were to further investigate the medium-term and sustained use and effect of PZP on cow and bull societies and their behaviour.

For reserves that are largely eco-tourism driven, the implementation of a PZP programme will have little effect on game-drive and safari activities. The shorter vaccine administration demonstrated by the helicopter darting (as opposed to tracking the elephants in vehicles and on foot to dart them) appeared to have a more consistent effect on the herds, with the least shift in core range during and after darting.

Prime Concern

The prime concern raised is that of the effect of the vaccine on reproductive behaviours. Under the PZP treatment, the target animal displays a normal oestrous cycle, cycling every 15-16 weeks, because although copulation still occurs, conception does not.

Therefore, under the PZP contraceptive, the frequency of mating and its accompanying disturbances is assumed to be far more frequent. Thus, with an increased frequency of oestrus, there is the potential for change in the frequency of association of both virile musth and non verile non-musth bulls with breeding herds as both sets of males compete for oestrous females.

In fact, bull association with herds decreased over the years, probably an effect of ageing in this relatively young population. The decrease in herd-bull association further illustrated that the PZP implementation did not affect the Makalali's bull hierarchy i.e. there were far more non-musth virile bulls than musth virile bulls and even in the absence of musth, mating and consort behaviour was highest in the three dominant musth bulls.

Furthermore, the non-musth virile bulls did not increase their associations with the herds. Thus, the treatments did not affect bull hierarchy or cow selection.

The results from this study demonstrate that there was no aberrant or unusual behaviour with the medium-term and sustained use of PZP on bull and cow societies.

As demonstrated in the KNP trials, the results of the PZP treated cows were as expected from cows whose behavioural patterns were not affected by the treatment i.e. there is no evidence to suggest that the PZP has any adverse effects on the behaviour of either the treated cows, their matriarchal groups or bulls.

Costs

There is a concern that contraceptive implementation may be cost prohibitive. The Makalali study has demonstrated that the highest costs incurred during contraception implementation are based on the helicopter costs, or more specifically, the costs of ferrying the helicopter to the site. Implementation and costs amount to R880–R1 000/elephant, fully inclusive of the darts, vaccine, helicopter and professional fee.

The results demonstrated in the Makalali study have resulted in the implementation of immunocontraception as an elephant management tool in 10 reserves, including Phinda, Welgevonden, Thornybush and recently, Tembe Elephant National Park.

However, in vitro studies have been underway with a different type of vehicle with the PZP vaccine. This is the so-called 'one-shot vaccine' that combines the initial three vaccinations from the KNP and Makalali-designed protocol into a single vaccination.

Thus, during the first year, only one dart per cow is required. Furthermore, the long-acting pellets are released at 1, 3 and 12 months, necessitating the first booster during the third year only. Thereafter, a single annual booster will be necessary to maintain immunity and contraception.

The first field trails were conducted in free-ranging elephants in May 2007 at Karongwe Private Game Reserve. The KNP trials and the Makalali study have culminated in almost twelve years of intensive investigation into the social and behavioural consequences of immunocontraception in African elephants.

Similar studies have been conducted on other long-lived animals i.e. horses (with treated animals developing new age classes i.e. 21-25 years, and > 25 years), with same-population studies spanning more than 15 years on Assateague Island National Seashore (Kirkpatrick & Turner 1996, Turner et al. 2002).

With such comprehensive studies demonstrating that PZP contraception causes no long-term behavioural changes, managers need to assess PZP immunocontraception as a realistic alternative management tool, particularly as part of a longer-term management strategy.

THE IMMUNOCONTRA-CEPTIVE RESEARCH TEAM AT MAKALALI INCLUDES:
AK Delsink, research ecologist, Makalali Private Game Reserve, Amarula Elephant Research Programme, School of Biological and Conservation Sciences University of KwaZulu Natal, Howard College, Durban, 041, South Africa. Dr Douw Grobler & JJ van Altena, Catchco Africa, P O Box 1148, Highlands North 037, South Africa. Prof. Henk Bertschinger, Veterinary Wildlife Unit, University of Pretoria, retoria 1008, South Africa. Dr Jay Kirkpatrick, ZooMontana, Science and Conservation Centre, Billings, Montana, U.S.A.



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