Cape buffalo: At the mercy of lions, drought and disease

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Text: Pieter van Wyk | Photographs: Pieter van Wyk and James Moodie 

Buffaloes at MalaMala are going through a tough time. Anyone who has been following our daily updates over the past months may have noticed this. Lions have been killing these bovines at a higher than normal rate and for a couple weeks, almost on a daily basis. In fact, quite often we’ve witnessed multiple kills in a day. The first two questions this raises are why is there suddenly an increase in kills, and why now? The next question is what are the possible consequences? However, before we answer these questions, let’s take a brief but closer look at our subjects.

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The Cape buffalo (not water buffalo) earned its place as a member of the Big 5. For those who don’t know, this term actually originated from hunting and refers to the 5 most dangerous (thus sought after) animals to track down and kill. Fortunately at MalaMala the camera replaced the rifle about five decades ago but the thrill of tracking down these noble beasts still remains. The word ‘buffalo’ is often synonymous with ‘lions’. Many books and documentaries refer to them as ‘eternal enemies’ and this shines a bit of light on the fact that lions don’t always walk away as victors. Buffalo often display a real sense of loyalty, commendable bravery and great strength when defending themselves and each other from a lion attack. They are not the dumb nor dull creatures as they may at first appear to be.

Whilst viewing a herd of buffalo, one can easily get caught up in just focusing on the individual members and this means they won’t see the forest for it’s trees. There is a lot more to them than first meets the eye. To know what it means to be a buffalo one must first understand its herding behaviour. Look past the curios young bull approaching the vehicle, look past the cute little calf and one will see a group of families who share resources and coordinate activities in a way that mirrors our own society. Status among individuals is instantly recognised by subtle signals such as a tilt of the head, body posture, vocalisations, direction of gaze and odour; all of which are broadly similar to signals we respond to, but of which we are often unaware.

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Herding also greatly benefits young, inexperienced buffaloes when it comes to the business of earning a living. Gaining knowledge as to where to find the best food at a given time in a certain habitat requires the knowledge that youngsters learn by associating with adults. Author Mitch Reardon maintains that buffaloes, to maximise the advantages derived from their elders’ collective wisdom, have developed a sophisticated communal decision-making system not unlike human voting. Their decisions are critically important because buffaloes are non-territorial, instead inhabiting clearly defined home ranges of 250-500 square kilometers that show little overlap (except during droughts) with neighbouring herds. Large herds move through their home ranges on a seasonal cyclic route, their grazing, trampling and fertilisation favours rapid plant regrowth, which in turn encourages repeat foraging. Their decision-making takes into account not only where the most suitable grass is but also where they have recently fed and how long the grass will take to recover as different grasses grow at different speeds. They also have to avoid patches depleted by competing herbivores.

So, back to our initial two questions; ‘Why the sudden increase in lion/buffalo kills and why now?’ The answer is linked to the drought we are currently experiencing and to understand this better we need to pause once more. Let’s glance back at times gone by.

In the 18th century, buffaloes were the most abundant ungulate species south of the Zambezi River with herds of up to 3,000 strong occupying a variety of different habitats. Today, their steep declining numbers across sub-Saharan Africa evokes a tragic sense of loss.

Rinderpest decimated buffalo populations at the end of the 19th century as it swept down to the Cape from Ethiopia. James Stevenson-Hamilton wrote in 1947 “…and everywhere it touched, exterminated or all but exterminated the buffalo.” Numbers in Kruger did bounce back not only due to the protection offered by the reserve, but also due to the immunity the survivors had acquired. He continued “The 15 or 20 animals which escaped rinderpest in lower Sabie have increased to some thousands.” Today they are distributed throughout this ecosystem, without a strong preference for any particular landscape.

By 1964 the Kruger’s population was 10,500. This unexpectedly high number prompted fears of heavy grazing pressure and over-utilisation and a cull was proposed. Further counts revealed that in 1967 the number had increased to 15,700 and then up to 19,000 by 1969. That year culling began, two years after elephants but without the public outcry. For the next 23 years about 3,000 were culled annually so as to maintain the population at approximately 30,000. But good rainfall years in 70’s saw the population grow to 35,000 by 1981. Then in 1982/3 a severe drought inflicted massive mortality on buffalo populations and the numbers sagged to 15,250. Buffaloes tend to lose condition faster than other ungulates and this provided lions with twice their usual food intake. The rains returned and the population picked up again but this was followed by deadly droughts between 1991 and 1995, which combined with an outbreak of anthrax in the northern half of Kruger, resulted in a 52% drop in numbers from 30,000 to 14,000. This massive crash ended the annual buffalo cull and it would never again be reinstated. By 2005 the number was up to 33,300.

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So, buffaloes increase rapidly under good conditions but they are also highly susceptible to droughts. It has become apparent that there is an overwhelming natural order at work, which functions best without human interference. Long-term studies in Kruger have demonstrated the cyclic nature of ecosystems and emphasised the importance of conserving the system with all its facets before management actions are implemented.

Recent complimentary studies have looked at the role large predators play in these fluctuations, with predator-prey interactions emerging as a central influence on the dynamics of many animal populations- far more than once thought.

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Norman Owen-Smith and Gus Mills analyzed 70 years worth of recorded lion kills found by field staff in the Kruger and they made some interesting discoveries. It appears that prior to 1946 buffaloes appear to have been virtually ignored as prey by lions and made up only 1% of all lion kills in the 1940’s. This number began to increase steadily as lions honed their buffalo-hunting techniques during times of drought. In southern Kruger that figure was up to 10% before the 1982/3 droughts, when that figure spiked to 30%! During the droughts of 1992 and 2003 buffalo remained numerically more important than zebra and wildebeest but then faded during the drop in numbers with zebra and wildebeest kills increasing. The buffaloes that survived the great die-offs were probably the fittest and would’ve deflected predation pressure to other species. In conclusion Owen-Smith and Mills note “changes in the abundance of buffalo were influenced by changing prey selection by lions but in their case vulnerability to predation cannot be disentangled from susceptibility through food deficiencies and possibly also disease”.

It is evident that buffalo populations are largely regulated by a dynamic relationship between periods of high and low rainfall and the manner in which lions respond to those events. Lions tend to target smaller and weaker buffalo and consequently take a heavy toll on calves with heavy juvenile mortalities occurring in large herds of over 500, whereas survival was much higher in herds of less than 100.

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One of the reasons buffaloes live in large herds is for defense against predators, but it is not hard to see why calf mortalities would be higher in big herds. Births are generally timed to coincide with the wet season’s optimal veld conditions and although a 26-54 kilogram newborn can stand after 10 minutes and can follow its mother within 2 hours, it needs several weeks to keep up with the herd. As the dry season advances grazing in the vicinity of perennial drinking water becomes trampled, forcing big herds to range up to 18 kilometers from surface water which they visit once or twice daily. A study partially done in MalaMala revealed that herds would trek up to 10 kilometers at night in search of better grazing. The long journeys at walking speeds of 5-6 kilometers an hour rapidly tired suckling calves and juveniles up to 2 years old. Distress, disease and parasitic infections exert their most profound impact at such stressful times. In their weakened state, calves lag behind or drop out of the herd altogether, becoming easy prey for lions and hyenas.

I mentioned ‘disease’ earlier; allow me to elaborate as this is directly related to the question ‘What are the possible consequences?’

One will find few buffalo at MalaMala that are disease free, indeed, only 2.3% of all South Africa’s buffalo are disease free. Most in Kruger have corridor disease, foot-and-mouth, brucellosis and/or bovine tuberculosis (BTB).

BTB first entered the Kruger ecosystem between 1950 and 1960, transmitted by infected cattle on 2 farms bordering the Crocodile River. Initial estimates predicted that it would take 40 years to spread through the Kruger’s buffalo population but it took just 15 years. As it spread its infection was also detected in lions, leopards, cheetah, hyenas, kudus, eland, impalas, bushbucks, baboons, warthogs, bushpigs, honey badgers and large-spotted genets. In these secondary hosts, infection often leads to severe loss of condition with large predators, especially lions, being particularly vulnerable as they are at the top of the food chain. In 2003 early symptoms of BTB-related ecological disturbances were being reported. For example, buffalo herds with a high BTB prevalence appeared more vulnerable to drought and because lions target the vulnerable their prey base accumulated a disproportionately high prevalence of BTB. Testing of sample lions in southern Kruger has shown that about 80% were infected or had been exposed to this highly contagious bacterial disease. BTB is having a big effect on lion social behavior. Male lions are dominant at kills and eat the choicest parts, such as lungs, which are a main sight for BTB lesions and bacteria. The disease weakens these dominant males and the knock on effect is not hard to imagine.

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In conclusion: History is repeating itself and this is not a once off or isolated incident. The drought we’re experiencing now is directly linked with the recent spike in buffalo kills made by lions. The Sand River is one of the few perennial water sources in this area and thus it has drawn a large number of buffaloes as they seek to quench their thirst. The lack of food and the increased distances herds have to travel between suitable grazing pastures and surface water is leading to increased fatigue and stress, which in turn affects particularly the young, old and weak as they become more susceptible to disease and predation. One could easily argue that Mother Nature is at work and the buffalo gene pool is being doused with chlorine ensuring no over-population and that only the fittest will survive thereby creating a healthier gene pool for the future. There is however serious cause for concern regarding the effects on lion populations as their increased intake of buffalo meat means increased exposure to BTB. As I mentioned in the previous paragraph, dominant male lions are at risk of getting weaker and this could lead to a higher turnover of dominant coalitions. Cub mortality then increases as they aren’t afforded the usual period of protection from their fathers. Younger coalitions become dominant prematurely and it can be argued that they aren’t yet equipped for it. Take humans for example, how many kids in their late teens or 20’s are in positions of power? Not many, because they’re not ready for that responsibility. The Gowrie males make for a good case study. Their immaturity was glaringly obvious during numerous mating attempts with the Styx pride- they didn’t seem to know quite how everything was supposed to work. They have also needlessly killed lionesses. It will be interesting to see how that dynamic plays out. Another argument being put forward is that lionesses are also entering adulthood prematurely leading to a possible trend in younger first time mothers. But more on that later.

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