News Archives - 2005

Lion Contraception
September 2005

A massive growth in our lion population and a crash in the market for free-roaming lions left Welgevonden with a large lion population during the last two years. This resulted in a massive and visible reduction in our prey population. However, although other predators like leopard and wild dog also had an influence, the large lion population and the way they have split up played a large role in this..

We are currently in the process of reducing the lion population, but are also implementing a contraception programme for all the remaining lionesses. This will allow us to control the breeding rate of the lions, and also allow us to decide which lionesses we want to breed with and give us a valuable tool to minimize inbreeding.

As with the elephants, the intention is not to stop all breeding but to reduce the breeding rate, and selected lionesses will be allowed to breed from time to time to retain a normal population structure. However, no breeding for the next two years is planned. This will hopefully allow the lions, especially the western pride, to re-establish their pride structures, and at the same time allow the predation on the prey population to stabilize. Hopefully the same will happen with the prey populations and that the downward trend of all prey species can be turned into an upward trend again.

At the time of writing, only two lionesses have been contracepted, but all the remaining lionesses will hopefully be contracepted by the end of October. The contraception is done by Prof Henk Bertschinger from Onderstepoort and is actually a very simple process. Because this is a first time contraception, the lioness is checked for pregnancy via sonar. If she is in an early pregnancy, a hormone treatment will abort the embryo. She then also receives the contraception drug, which is in the form of a small tablet that is implanted under the skin and has a slow release time. This drug will work for 12 to 18 months, after which she needs to be contracepted again if we don’t want her to breed. If we do want her to breed, she is simply not contracepted again and will fall pregnant after 18 months without any negative consequences. Only time will tell how effective this programme will be, but we are confident that we will achieve our objectives.

Elephant Contraception
October 2005

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. However, recent trials on a private reserve in the lowveld have shown immunocontraception to be an extremely effective method to stabilise elephant populations in relatively small conservation areas and this obviously represents an exciting new possibility for elephant management.

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 three years.

pZP contraception has been successfully applied at Makalali Game Reserve since 2000 with 100% reproductive control. More recently, other private reserves have adopted this procedure as a means to manage their elephant populations. To date, no changes in social behaviour have been recorded. However, the use of pZP contraception as a mechanism to manage elephant populations in small reserves remains a relatively recent development and there is therefore limited data on the response of the elephant population in terms of social behaviour. Consequently, Welgevonden is in a position to play an important role in advancing research on contraception as a means to control elephant numbers in small, confined reserves.

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.

The primary vaccination was completed at the end of September, with 42 elephant cows and young females being vaccinated. Although the herds initially reacted to the low-flying helicopter, no problems were reported and the herds soon reverted to their normal, calm demeanour.

Fires on Welgevonden
October 2005

On the evening of Monday the 26th September, multiple lightning strikes both on Welgevonden and on adjoining properties resulted in extensive fires in and around the reserve. The strong winds and high temperatures combined to create extensive fire fronts that moved extremely quickly. At the same time, lightning strikes resulted in fires across the entire Waterberg region and reports indicate that vast tracts of land from Nylstroom to Thabazimbi were burnt.

The fires on Welgevonden have burnt approximately a third of the reserve's surface area (11 000 ha), predominantly in the southern, south-western and south-eastern sections. The Welgevonden management together with considerable assistance from almost all lodges intervened where necessary to ensure that lodges and other infrastructure within the danger zone were suitably protected. No lodges were damaged and there was very little damage to other infrastructure on the reserve. Also, after extensive inspection of the burnt areas, it is apparent that almost no game was killed or injured by the fires.

Although at first glance such extensive fires appear extremely destructive, their impact on the ecology of the reserve is extremely positive. Historically fires such as these would have burnt through the region on an annual basis, and they are critical to the functioning of the ecosystem. Fires ensure the continuation of nutrient cycling by releasing nutrients held in old plant material, they remove moribund grass and facilitate a flush of highly nutritious new growth, they limit encroachment by woody species and they necessary for the germination of numerous seeds.  Hence, even though the ferocity and extent of these fires was indeed alarming, their impact on the ecology of the reserve has been very favourable, particularly considering that they burnt in a natural manner and have burnt a suitably extensive area. A fire of this magnitude will contribute greatly to maintaining a patch mosaic of habitat types across the reserve, and this is essential for the maintenance of biodiversity.

Lion Collaring
October 2005

Two HAWK105 GPS/GSM radio collars were kindly donated by Trisha Wilson from Izingwe Lodge. HAWK105 consists of the latest in GPS (Global Positioning System) and GSM (Global System for Mobile Communication) technology. The device fitted to the animal, determines position accurate within 10 meters at user's specified times. These time schedules (daily or weekly) can be programmed and reprogrammed while the animal is in the field.

The gathered position data can be logged or sent to the user immediately. The user will download the data from the Internet using the HAWK105 software package. Schedule changes can be made using the software package or phoning the control center. All the data is secure.

As backup to the above mentioned system a beacon transmitter is activated automatically in the case of no GSM or GPS coverage. Battery life depends on the number of readings taken per day. In a well covered (cellular) area the estimated battery life for 5 readings per day is 2 years per 'D' type battery.

At the end of September one lioness in the south of the reserve was fitted with a radio collar, while the second collar will be fitted to a lioness from the western pride in November.

These collars will allow us to gather new data on the movements and ecology of the lions, and will focus specifically on predator-prey relationships.

We are in the process of reducing our lion population, and the data gathered will provide valuable knowledge of the influence of the lions on the prey population. The collars are currently set to take a five readings a day, but might change as needs of the project change.

The adjacent map shows the actual positions of the southern lioness as collected with our first download. The lions concentrated mostly on the newly opened Sterkfontein property.

We would like to thank Trisha for her donation and interest expressed in research on Welgevonden.

Aerial Game Census
October 2005

The annual aerial game census was done in the middle of September during hot and windy conditions. Normally the census was done wrapped up in jackets, gloves etc, but this was the first year that we wore shorts and short sleaved shirts. Luckily the visibility was excellent, although flying conditions was not ideal.

The numbers for most species are down from last year, which were to be expected giving our high predator population, very dry conditions and bad breeding the previous two seasons. It was noticeable that the major prey species decreased sharply. This was also the first year that a large decrease in impala numbers was seen. However, we also noticed that there was less of some of the smaller antilope species like mountain reedbuck, nyala and bushbuck. The wild dogs are probably the big culprits as they hunt extensively in the valleys. But, as usual, he elephant numbers are up by the normal margin of 8%!

It should be kept in mind that the census figures are not intended to give a 100% accurate figure for all species, and that individuals of some species will be missed, especially the small, shy animals like bushbuck etc. This applies especially to the smaller animals that tend to be alone or in small groups. Large animals or animals in average to large herds will be counted relatively accurately. The principle behind an aerial census is to provide trends of what is happening in the different populations, and not exact figures. The census figures are available to landowners in the member’s section.