15 April 2014, 12:04
Zig MackintoshZimbabwe's elephant over-population problem.
This is a follow-up report to the one that we submitted to USFWS through Conservation Force last week. This report has also been sent to USFWS. The elephant in the room, excuse the pun, is that Zimbabwe does not have a problem with declining elephant numbers but a serious overpopulation of elephant.
Zimbabwe’s Elephant.
In light of the recent ban on the importation of sport hunted ivory by the US Fish and Wildlife Service (FWS) it is evident that they have no idea of the actual situation of elephant numbers in Zimbabwe.
Zimbabwe is facing a serious problem of over population of elephant, which is causing critical environmental damage especially in the Hwange National Park. But how has this been allowed to happen? Why has nothing been done about it?
When the park was first founded it was realized that the provision of water was going to be the key factor in its establishment. By July every year, in all but exceptionally wet seasons, most of the water had dried up and water-dependant game species were forced to leave the park.
As water points multiplied and the park opened up there was an animal population explosion with elephant leading the way. As the elephant numbers increased, the damage to the habitat became all too evident. The authorities were faced with two alternatives, either to cull back the population or to let nature take its course.
The widely quoted theory used to oppose culling is known as the stable limit cycle hypothesis.
This hypothesis can be viewed as a cyclical relationship in which elephant numbers increase while thinning out the forest and then decline when trees become sparse.
With the elephant’s decline the trees regenerate and the cycle is repeated once more.
There is a time lag whereby elephants do not respond quickly to environmental change, hence the trend of elephants and the trend of trees are similar to sine waves; the peak of trees being slightly ahead of that of elephants.
The Tsavo national park in Kenya is one of Africa’s largest game reserves extending over 12 800 km2. In the early 1970’s the park was faced with a serious over-population of elephant similar to that of Hwange Park.
The Kenyan authorities decided to follow the stable limit cycle hypothesis and leave things to themselves. In this decision, however, major factors that created the problem were over-looked and false assumptions made.
Firstly animal populations were confined within artificial man-made boundaries it was not a “natural” situation. Secondly early elephant counts in the 1960’s were grossly inaccurate representing less than one tenth of the actual numbers. The last absurd assumption was that dead bodies return much-needed elements to the soil.
The irresponsible decision to leave Tsavo to itself resulted in the desertification of eight thousand square miles of Commiphora canopy woodland. Thirty thousand elephant and hundreds of black rhino died in the Tsavo debacle from starvation, constipation and heart disease.
The Tsavo type solution was unacceptable to the Zimbabwean authorities. Not only would the environment be totally destroyed but it would also result in: a waste of meat in a protein deficient country, a loss in potential revenue from skins and ivory and there was also the ethics involved in allowing animals to die of starvation.
Culling appeared essential to ensure not only the conservation of the elephant themselves, but also the many selective grazers and savanna dwelling species that lived in the grasslands. It was also considered that as the Hwange Game reserve was created through the artificial provision of water, it had to be managed.
In terms of the Zimbabwean Parks and Wild Life Act, the Department of National Parks and Wild Life Management has a responsibility to protect all ecosystems and their components and not individual species. Consequently a program to reduce elephant numbers was initiated.
For culling to be effective more animals must be removed than are recruited into the population each year. It only takes around 15 years for an elephant population to double in size so there is little risk in over–culling. Hardwood woodlands on the other hand take ten times as long to recover from elephant damage and only where the effects are reversible. So even if a mistake was made in calculating off-take, it would only take 5-7 years to have a substantial increase in the elephant population where it would take over 100 years for the hardwoods to increase.
Caution was exercised with the culling program in Hwange. From 1960 until 1970 only a couple of hundred elephant were eliminated a year. In 1971 and 1972 two thousand elephant were shot.
Soon after this the program was stalled due to the liberation war in the country. No major culls were carried out until 1980.
In 1983 the goal was to reduce the population from 23 000 to 12 000, the level at which serious habitat damage in the Park first caused concern. This figure was calculated taking into account vegetation composition, food availability and climate. It was acknowledged that even 12 000 elephant was too many as the state of the vegetation in the 1960s had not been closely monitored and there had probably been considerable habitat modification before it was recognized as such.
Furthermore, when the population reached 12 000 it was already increasing exponentially so that the damage then reported had actually been caused by fewer animals.
The ideal situation would have been to reduce numbers to below the ecological carrying capacity and then allow them to build back up. This was, however, logistically impossible with the limited resources available.
In 1980 there was a huge backlog of culling throughout Zimbabwe, and a lack of the essential equipment with which to do it.
With serious over-populations in a dozen different areas, and knowing that as elephant numbers increase and resources decline the rate of destruction accelerates, the authorities could only do the best that they could.
The Hwange operation was staged over three years as it was impractical to cull and recover products from 11 000 elephant in a single dry season. Continued population growth during this period meant that some 13 000 animals had to be shot. The exercise was completed in 1987, but was hardly over before there was a major influx of elephant into the Park from the seriously over- populated Chobe National Park and adjacent areas in Botswana.
The 1987 post-cull census in Hwange was back to over 17 000 head and included recently tagged animals that had traveled over 150 km from the west of the Chobe National Park.
Since 1987 there have been no substantial elephant culls in Hwange National Park, for a variety of reasons.
The international ban on the sale of ivory and elephant products has made culling prohibitively expensive. The cost of mounting a culling operation of 1000 elephant is in the region of 140 000 US dollars.
Whilst some money can be recovered through the local sale of ivory, meat and skin, the only way to recuperate the expense of a culling operation is either through the international sale of ivory or with foreign funding.
Two one-off sales of raw ivory have taken place since the elephant was listed on Appendix I in 1989. The first was in 1999 when Botswana, Namibia and Zimbabwe sold ivory to a single buyer (Japan) and the second took place in 2008 when Botswana, South Africa, Namibia and Zimbabwe sold to China and Japan. But this was stockpiled ivory from previous culls.
Examination of the returns from the sales indicates that the range states lost 66-75% of the value expected under normal trading conditions. The practice of selling ivory stockpiles at lengthy, irregular intervals departs from normal commercial practices. It results in substantial losses to those selling ivory and, because the supply of legal ivory is erratic and uncertain, it provides no incentives to ivory traders to confine their trade to legally available ivory.
The present decision-making mechanisms of CITES do not readily lend themselves to providing incentives to conserve elephant.
Bans and intermittent sales of ivory stocks cannot, by their very nature, include potential benefits from sustainable use. The crushing of ivory stockpiles is even less helpful.
Whether the money from the sales went back into conservation projects or not is irrelevant, the sales did nothing to alleviate the elephant over-population problem.
When Ted Davidson founded the park in 1922 there were between 2000 and 2500 elephant in Hwange.
Today the population has exploded to around 50 000 or 2.9 animals per square kilometre. If the aim is to maintain woodlands and areas of "old growth" in order to maintain the levels of biodiversity that go with it, then these will likely decline or be lost at elephant densities even as low as 0.3 elephant per square kilometre in savanna woodlands in areas of less that about 750mm of rainfall per year.
Kruger National Park in South Africa maintained its elephant densities at about this density for years (i.e. 6,000-7,000 elephant) and still continually lost big trees and reduced the populations of species that depend on big trees. How many species may have been lost to the system is not known.
Shumba pan is one of the park’s most well known waterholes. When Ted Davidson was first scouting the area with his San trackers, they led him to one of their secret wells at Shumba. The water at that time was accessible just below the surface. Today water is pumped from ninety metres below ground for 10 months of the year.
As with all of the pumped pans in the park, wave after wave of elephant herds can be seen at the waterhole throughout the day and night, a far cry from their elusive, nocturnal behaviour of the 1930’s. Because of the elephant size and the sheer numbers, other game animals are chased from the water holes, sometimes to their ultimate detriment.
If the Zimbabwean wildlife authorities had sufficient money, acted in defiance of world opinion and started culling back the elephant population in Hwange, the end result would be much the same as in the 1983 culling operation. Botswana and notably the Chobe Game reserve is still critically over populated with elephant and Hwange would once again be swamped with elephant.
Without a simultaneous, co-ordinated culling operation between the two countries with the full backing of the international community, the total destruction of this fragile habitat will be complete.
By supplying year-round water to Hwange National Park a water-dependant, artificial environment has been created. An unnaturally high population of elephant, created by this provision, is destroying a delicate ecosystem. Turning off the water supply will not solve the problem, as there would be a mass, uncontrolled die-off of most wildlife species including elephant. If water continues to be pumped and nature left to itself, a disaster on a scale surpassing that of Tsavo National Park will result.
Control and management of elephant numbers, not only in the Hwange National Park but also in neighboring Botswana is the only solution.
The elephant poaching scourge that is affecting parts of Africa and the over-population problem that face Zimbabwe and Botswana can be directly linked to the ban in the international trade in ivory. Africa has been denied the use of an important tool in its wildlife conservation toolbox. The ban of the importation of sport hunted ivory by the US Fish and Wildlife Service is removing another of those important tools.
References:
Martin R.B. (1992). Relationship between elephant and canopy tree cover. Appendix 9 in Elephant management in Zimbabwe. 2nd Edition. Eds R.B. Martin, G.C. Craig and V.R. Booth. Department of National Parks and Wild Life Management, Zimbabwe. 124pp
Craig G.C. (1992). A simple model of tree/elephant equilibrium. Appendix 10 in Elephant management in Zimbabwe. 2nd Edition. Eds R.B. Martin, G.C. Craig and V.R. Booth. Department of National Parks and Wild Life Management, Zimbabwe. 124pp
Child G. (1995). Wildlife and People: The Zimbabwean Success. How the conflict between animals and people became progress for both. 267pp