Elephants and the Carrying Capacity of Habitat

In 1960, Dr Graham Child, who was then working for the United Nations in Botswana, told the Botswana government that the elephants of Chobe were destroying the riverine forest along the Chobe River; he said this indicated that the elephants had exceeded the elephant carrying capacity of the Chobe habitats; and he recommended that the elephants be culled.

He did not quote the size of the Chobe elephant population at that time – because he didn’t know it. Nevertheless, no action was taken.
In 1974 the United Nations also recommended that elephants be culled in the Chobe area. Again no action was taken.

In 1960 Hwange National Park’s elephants, in adjacent Zimbabwe, numbered 3500; and at that time they were totally eliminating a number of major tree species in the park – including the Mukwa (Kiaat) (Pterocarpus angolensis), a number of acacias, and several others.

Although the National Parks Board did not know Hwange’s elephant carrying capacity at that time, it recognised that 3500 was far too many – because that number was “irreversibly damaging the Hwange habitats”. Consequently, the Board recommended that the elephant population be reduced to 2500 – to see if the damage could not be stopped by simply reducing elephant numbers.

NB: A large number of elephants were killed (on the outskirts of the Hwange park) to effect this reduction but the target number was never achieved. It is important to record, however, that the recommended elephant carrying capacity for Hwange at that time (2500) amounted to one elephant per 5 square kilometres.

By 1965 Hwange’s elephant population had increased to 6000 – due to immigration from Botswana. An official elephant culling operation – inside the national park – then commenced; and between 1965 and 1988 some 500 to 1000 elephants (sometimes more) were removed annually. Initially the target was to reduce the population size to 2500 but as the years went by, this target was, unfortunately, arbitrarily relaxed.

At the beginning of the 1980s Hwange’s elephant population stood at 23 000 and the management target had been changed to one elephant per one square kilometre (that is 13 000). I was then the Provincial Game Warden in-charge of Hwange and I disapproved – because I believed (and still believe) that just one elephant too many would still ultimately convert the national park into a desert; and my concern was for the damage the elephants were doing, every day, to the park’s biological diversity.

But I did not have the rank or the political clout to change the biological recommendations. By then – at the beginning of the 1980s – senior government officials were beginning to voice concerns about:

“What the public would think” if we killed too many elephants.

And that attitude – which still prevails – if it continues to prevail – is the factor that will ultimately destroy Africa’s national parks altogether.

To be sustainable, wild animals of all kinds HAVE to ALWAYS be maintained in numbers that are within the carrying capacity of their habitat.

Today, Hwange is carrying roughly 50 000 elephants (between 35 000 and 80 000 depending on elephant movements in-and-out of Hwange from Botswana). 50 000 elephants is 20 times the number that was recommended in 1960.

NB: This important reality reflects one of the few available denominators for determining elephant management principles anywhere and everywhere – because there are now no more examples of pristine habitats in Africa in which elephants exist in numbers that are at, or anywhere near, the optimum elephant carrying capacity of their habitats.

One other national park – where I am reasonably certain of the game reserve’s past elephant carrying capacity – is Kruger. Without going into elaborate explanations, my calculations tell me that Kruger’s elephant carrying capacity (circa 1955) – when the habitats were still healthy and undamaged – was 3500. And – in terms of the elephant population density – that works out at one elephant per 5.7 sq kilometres. And may I point out that this equates very closely to the “1960 guesstimate” for Hwange (at one elephant per 5 square kilometres).

There is a dispute at this time as to just how many elephants Kruger is actually carrying. The present day scientists say the number has “stabilised” at 17 000. Dr Salomon Joubert, a previous and long-standing large mammal specialist at Kruger – and previously Kruger National Park’s Administrative Director – insists, however, that the number is in excess of 30 000. I go along with Dr Joubert’s assessment. We both believe the Kruger elephant numbers are being “cooked” for doctrinaire purposes.

NB: Since 1960, in ALL the deciduous woodlands that once existed throughout Kruger National Park’s 20 000 square kilometres, the elephants have reduced the number of top canopy trees by “more than 95 percent”. And the understory plant communities – that once lived in their shade – have disappeared completely.

I want you to think what that reality has done to the once great biological diversity of Kruger National Park. And I want you to start believing that an equivalent ecological catastrophe pertains in northern Botswana, too.

An elephant count in Botswana carried out in 1990 determined there were 60 000 elephants in the country. The count in 2000 was 120 604 – reflecting an average annual incremental rate of 8.3 percent. Although this incremental rate has been called “biologically impossible”, I accept it. The average annual incremental rate of the Kruger elephants – throughout the 27 years of the Kruger culling era – was 7.5 percent. And I accept the 2013 Botswana elephant count of 207 000, because it fits in with the elephant population growth-trend of that time.

The elephants that live in northern Botswana are part of a single mega-population that includes the elephants of North-Eastern Namibia, Eastern Angola, the southern part of Western Zambia; and Western Zimbabwe (Hwange). During the rains – when surface water is not limiting – these elephants roam throughout all these countries; returning to their more permanent home-ranges during every dry season. Some animals may sometimes linger in the distant parts of their expanded wet season home ranges for longer periods – when extra-heavy seasonal rains have benefited these countries’ habitats. One should not be surprised, therefore, at annual differences in the elephant population numbers in any and all of these countries.

NB: There are three status categories for elephant populations: UNSAFE; SAFE & EXCESSIVE – and they all have different management requirements.

UNSAFE populations are low in number, decreasing and – if no remedial management action is taken to assist them – they will pass into extinction. Such populations should be “protected from all harm” – which is termed “PRESERVATION MANAGEMENT”.

SAFE populations are healthy in number, they are breeding well and expanding, but they have not exceeded the carrying capacities of their habitats. These populations should be culled or hunted every year to keep their numbers “in balance” with their habitats’ carrying capacities. This kind of treatment is called “CONSERVATION MANAGEMENT” (or sustainable-use management).

EXCESSIVE populations exceed the carrying capacity levels of their habitats; they are constantly over-utilising the resources of their habitats; they are constantly degrading the quality of their habitats; they continually cause massive biological diversity losses within their sanctuaries; and they should be quickly and drastically reduced in number – until their numbers fall below the carrying capacities of their habitats.

BOTSWANA’S overall elephant population is GROSSLY EXCESSIVE!

One thing is uniform to elephants everywhere. An annual incremental rate of 7.2 percent will cause elephant populations to double their numbers every 10 years.

But as the population groups increase, they begin to over-utilise the resources of their dry season habitats and that will cause the incremental rate to decline – which is something that is happening in Botswana. We cannot, and must not, therefore, be too stubborn about accepting or rejecting actual elephant population numbers – because, in the end, exactitude in this regard is not the issue.

What is important is the impact that an elephant population (no matter what its number) has on the dry season habitats that it occupies every year. This is a reflection of the size of the population relative to the sustainable elephant carrying capacity of its habitat.

NB: The elephants of Botswana have shown that they can roam away from water, each day of every six-months long dry season, for a distance of 25 kilometres during which ‘ranging’ they somehow find enough food to stay alive. But in so doing so, they strip every vestige of food (all edible grass and browse) within that 25 kilometre range of their water supply. So that 25 kilometre radius becomes a virtual food-desert for all the other game animals which share the elephants’ habitat during every dry season. These lesser animals cannot walk 25 kilometres every day to find food. That is why, when the 2013 elephant count was made public, the Botswana government informed the world that “all other species” had declined by between 60 percent and 90 percent.

The elephants suffer too. At the height of every dry season, hundreds of elephant mothers with small babies at foot, suffer the consequences of this starvation regime.

They stop lactating and hundreds of starving baby elephants are abandoned because they cannot keep up with their mothers on their long daily treks.

These babies die of starvation, heat-fatigue or thirst, or they are killed and eaten by hyenas and lions.
And the general biological diversities of the affected national parks suffer immense losses of species of both plants and animals.

So, it would be a good idea for us to have at least “some idea” of the elephant carrying capacity of the Botswana dry season habitats. How do we come to determining that?

Well, if we can accept the fact that elephants can and do double their numbers every ten years going forwards; we can determine elephant population sizes at any time in the recent past by extrapolating backwards. If we accept, for example, that there were some 60 000 elephants in northern Botswana in 1990; there must have been 30 000 in 1980; 15 000 in 1970; and 7 500 in 1960…. which was when the elephants started to demolish the Chobe riverine forest strip. 7 500, therefore, were too many elephants for Botswana in 1960. So, maybe 5 000 would be a good guess at the elephant carrying capacity for Botswana in 1960 – at which time the habitats were still reasonably healthy? Today, by comparison, all the habitats in Botswana’s elephant sanctuaries have been trashed.

I have gone to great pains to explain to you that the ACTUAL elephant carrying capacities of all our elephant sanctuaries in southern Africa are minuscule compared to the very large numbers of elephants these game reserves are ACTUALLY carrying. In other words, all our national parks are carrying grossly too many elephants. And I have explained that for a reason. I want you all to understand that whatever consumptive elephant management regime Botswana adopts from now on, it is unlikely to have any impact on the size of the elephant populations that currently pertain.

 

 

Ron Thomson

RON THOMSON His passion, today, is concerned with creating a better informed society – better informed, that is, about “best practice” wildlife management and the wise and sustainable utilization of our wild living resources for the benefit of mankind. He has a strong and passionate commitment to exposing the menace and iniquities of the animal rights doctrine. He is a founding member of the True Green Alliance (TGA) and, for the duration of 2016, he was its President. In January 2017 he was appointed CEO. The TGA is affiliated to South Africa’s wildlife Industry insofar as it has undertaken to fight the industry’s battles to overcome pernicious opposition from the South African and international animal rights movement.

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2 thoughts on “Elephants and the Carrying Capacity of Habitat

  • October 18, 2018 at 10:29 am
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    My problem with the whole approach is that no differentiation is made between the two extant species of elephant in Africa, i.e. the African bush elephant (L. africana) vs. the African forest elephant (L. cyclotis). I think few people actually realise that Africa doesn’t just have one elephant species, but two. In my humble opinion, it is indeed the African forest elephant that deserves the attention of the world as they find themselves in a state of peril. Issues of habitat degradation, exceeding carrying capacity and loss of biodiversity because of mismanagement and overpopulation of [African bush] elephants in Botswana and Kruger distract the attention from the African forest elephant. In the process the plight of the African forest elephant is totally overlooked. And that I find extremely sad and deplorable.

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  • October 19, 2018 at 8:28 am
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    Before the question of quite what to do about elephants which are destroying their own food-supply system and desertising their environment and to the cost of all other wildlife, I’d respectfully suggest that the outer shell of stubborn ignorance of those, very often on the other side of the world who magically seem to have a greater understanding than the foot soldiers on the ground, be dealt with.

    Somehow, those funds which are being directed towards the ARs brigades need to be re-directed and to where they’re needed. Achieving this isn’t going to be easy, and it will only work if the same level of guile is applied as we see from those who fund and support the often and totally counterproductive, Animal Rights groups. Simply advising the world that the AR groups are wrong, has never been, and will never be, enough.

    Those who would campaign for ARs will be just as aware as the rest of us of the level of complicit corruption within many established governments. We have to ask if rather than appealing to the good sense of those responsible – those government ministers, if they are in fact offering personal incentives. Quite how thorough an investigation could be, I’m not sure, but if I’m right in my supposition, missuse of charitable funds would have the AR people doing to themselves, what the elephants are also doing and to themselves.

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