Hyena: Scavenger or Predator? The Human Influence on Hyena & Lion
by Steve Pope
Since the 1970‘s there have been some dramatic animal population fluctuations in world-renowned game regions, including predator population crashes, brief explosions of prey numbers and unnatural establishment of hyena packs, where the latter have changed their habit from scavenging to predation and thereby profoundly affected both predator and prey populations. I argue that these fluctuations are a direct result of human influence through culling, poaching, hunting and food made available to animals from camps.
In Mana Pools impala were culled every year from 1969 until the bush war intervened in 1973, but by 1980 there was a balance between prey and predator, lasting until 1989. In that year, however, the predator populations crashed and the impala population exploded, coinciding with hyena packs becoming established.
In the early 1980s it was possible to see three different lion prides on an early morning drive. Leopard were prevalent and at one time we frequently saw six cheetah. Tourists do not visit a game reserve to view large herds of impala or troops of baboons. Elephants are an attraction, but what really stirs the adrenaline and brings tourists back is the sight of predators hunting and feeding.
So, what happened to the predators? Right through the 1980s they were plentiful, but since the early 1990s it has been difficult to see them. From 1982 until 1989 I had only two safaris without sighting lion, in the next year alone we had two safaris with no lion sighting, and by 1991 we were lucky to see them at all. Hyena that were rare in the early 1980s, by the mid to late 1980s were being photographed as frequently as the predators.
In 1987 I noticed that only one pride of lion on the river terraces had new cubs. I became concerned the next year when I again noted that there were no new cubs, only those born in 1987, and in 1989, by mid dry season again there were no new cubs, the only young lion being the sub-adults born in 1987. The lion population had crashed and leopard and cheetah numbers dropped dramatically as well. The result was an explosion in the impala population during 1990 and 1991.
I started the 1992 season already disillusioned, only to discover that National Parks was planning to cull impala. Viv Wilson, in his book “Lions, Leopards and Lynxes” (1981), states, “as a result of extensive culling of impala, wildebeest and elephant in the Wankie National Park the hyena population had increased tremendously and they were completely unafraid of humans and, for that matter, even of lions.” Mr M G Hornocker’s “10-Year Study of Mountain Lion” published in the National Geo- graphic of July 1992, states, “A Mountain Lion’s territory is de- termined by the food supply”. Since, according to ecologist Kevin Dunham impala were the predators’ main food supply, I thought it made sense to attempt to stop the cull. With the predator population already under increasing threat from the hyena, I argued that to reduce the main predator food supply would be disastrous and that instead hyena numbers should be reduced.
However, there were so many impala that they had become known as “Mana Goats” in a derogatory manner. In a degraded environment goats are seen to be numerous and to do well, and are mistakenly thought to have caused the degradation. The goats do well because their diet is so varied - they browse on trees and bushes and even feed on most weeds. The fact that impala are 50% grazers and 50% browsers was ignored; the fact that their numbers were high because the habitat could support them was ignored, and so 5000 impala were culled. Large numbers were wounded and not recovered, providing an unnatural food supply to the hyena. There were reports of up to 30 hyena following the cull vehicle and running off with carcasses before they could be recovered.
Events in the Zambezi Valley provided further evidence that human influence had led to the increase in hyena numbers. In 1984, when 4,000 elephant were culled, a meat contractor, having processed what he could from the 14.7 shot everyday, left hundreds of kilograms as an unnatural, abundant food supply for the hyena, initiating the increase in hyena numbers. This un- natural supply was augmented by canoe safaris bringing in rubbish, by hyenas thieving meat from unwary campers, and by the feeding of hyena for photographic purposes.
Lion had also benefited from the elephant cull but given their social behaviour where abundant food equals cub survival, but poor food supply equals cub mortality, when hyena deprive lions of their kills then cub deaths go up and the population crashes. Also, lion do not raid dustbins.
By 1990 the hyenas were so numerous that they had become self-subsisting. Adopting the tactics of Painted Hunting Dogs, they could now hunt for themselves and could drive a pride of lion off a fresh kill. Hyena cubs, raised in dens, were protected from lions, whereas the greater number of hyenas made it more difficult for lioness to protect and feed their cubs.
Following is an account, by Miles Bennet, of a lion/hyena incident in Mana Pools in June 1994: - “The week before we arrived four lions had killed a buffalo but, within an hour of the kill, had been chased off by at least 20 hyena. Despite numerous game-drives we did not see any lions until our last day when, at Long Pool we came across several excited hyena running in and out of a dense thicket near the pan. We spotted a lioness hiding and could hear another male nearby calling to her. A number of hyena would respond to the lion’s calls by rushing out of the thicket to look for the lions, then rushing back into the thicket where there was obviously a kill. This carried on until the lioness broke cover. At once all the hyenas (we counted 21) left the kill and chased the lioness. They surrounded her and took turns attacking her from behind, and as she turned to defend herself, others would attack her from the rear. A large male lion ran in from the tree line to help the lioness. He sent one hyena somersaulting for some 10 meters, but he too ended up being surrounded with the lioness, being attacked on all sides. The male we had heard calling to the lioness earlier now broke from cover and went to help the two, as did an elderly lioness from the southern side. A fierce fight erupted between the four lion and 21 hyena, with the hyena eventually returning to the kill. The lion, all looking exhausted, lay down and rested before moving off. The kill was a young elephant, about 3 years old. We are of the opinion that the lions made the kill and were chased off by the hyenas”.
It is generally claimed that one adult pride male lion present at a kill is often enough to deter and prevent hyena from taking over. The above description illustrates that hyena were so dominant that not even two males could defend the kill.
In 1992, when National Parks first allowed visitors to Chitake Spring, I discovered, on two reconnaissance trips, a large pride of 22 lion and no sign of hyena!! Here was an isolated ecological oasis that hadn't been culled, hunted, poached or hosted tourists. The few hyena do not challenge the lion at all. Ten years later, they have never been seen in numbers of more than seven, which means that they are still fulfilling their traditional role as scavengers. I have often proposed that Chitake be regarded as a norm for comparison.
I discovered that the same scenario of burgeoning hyena and falling numbers of lion had occurred in the hunting concessions. I was told that in the early 1980s, if an elephant was shot, a pride of lion would appear, but by the early 1990s it would be a pack of hyena. Lion were so scarce that the Mashonaland Hunters' Association hunters put a voluntary ban on hunting them. At the same time, there were such large packs of hyena that they were put on license to be hunted. Writing of the effect on lions of the theft of their kills by hyena, Rob Oostindien proposed that Parks introduce a management cull operation for the harvesting of hyena.
In the meantime, I studied numerous documentary films, mostly filmed in Botswana Savuti, portraying hyena as predators. They are not scientific studies but they showed Spotted hyena attacking a large pride of lion and depriving them of their kill. What was happening in Botswana was exactly the same as was happening on the river terraces at Mana Pools. Worse, the filmmakers were claiming that lion and hyena were eternal enemies, and that the hyena were super predators. What had happened to the notion that hyena were scavengers? I knew that to argue this point I would have to show that the hyena in Botswana had also benefited from an unnatural food supply.
In Gus Mills’ report on his study of Spotted hyena in Namibia, he shows that when hyena hunt, two thirds of their kills are young, rather than adult. The film, "Patterns in the Grass" claims that the ecological damage from the slaying of a zebra foal by hyena is far less than that from the loss of a full-grown zebra killed by lion, stating that “many more adults are killed by lion” and “as older mares and stallions are cut down, knowledge accumulated over countless seasons of migration are lost”. This implies that it is ecologically better to have packs of hyena than prides of lion!!
The film shows a hunting party shooting a zebra and removing the skin for trophy, leaving the entire carcass for scavengers. It then blames the decline in zebra numbers, from 48,000 to 7,000 between 1981 and 1991, on poachers. It seems far more likely that hyena packs, established on hunted and abandoned zebra carcasses, are responsible.
There are hordes of hyena in the Masai Mara in Kenya, and in Serengeti and Ngorongoro in Tanzania. In the early 1900s these areas were the venue for most of Africa’s hunting. It is reasonable to presume that these hunts provided an unnatural food supply to the hyena. It is argued that prides of lion do co- exist with these packs of hyena, but those regions are open grassland plains with a much greater biomass of prey animals. Recently, a Mrs. Jenna Sutton informed me that in 2001, a lodge where she was staying in the Masai Mara was feeding a pack of 30 hyena.
In January 2002 a meeting was called in Zimbabwe to discuss the status of lion in the Zambezi Valley. There was talk of banning hunting of lion in Botswana and both National Parks and the hunting operators were concerned that pressure would force Zimbabwe to take the same action. I presented a paper to demonstrate that packs of hyena hunting for themselves and harassing prides of lion were abnormal, and were caused by human action, and that the hyena should be controlled. I also tried to show that the hyena had evolved as a scavenger. In “The Safari Companion” Richard D Estes says that the Spotted hyena utilizes carcasses more efficiently than any other carnivores. Bones, horns, hooves, even teeth are digested within 24 hours. In “The Behaviour Guide to African Mammals” Estes goes further to say that the desiccated corpses of wildebeests that died months earlier are consumed and yield protein, fat, calcium, phosphorous and other minerals sufficient to suckle young. No true predator would even survive on such a food supply. This description of a highly efficient digestive system is of an animal that spent millions of years evolving as a scavenger, utilizing a food niche unused by predators.
My paper was generally well received; the authorities said that more statistics were required. Of greatest interest to me was the information gathered from hunters, all claiming that in their concessions the lion populations had recovered since hyena had come on quota. Bill Bedford provided hunting statistics for lion and hyena, presented in a graph below. The graph illustrates clearly that in the early 90’s very few lion were hunted (in 1994 none at all) but as the number of hyena offtake increased so the number of lion, on quota and hunted, also increased. Some would not accept my proposal that hyena are supposed to be scavengers and should not be dominating prides of lion. Someone claimed that the hyena has a consistently larger heart relative to the lion, and a foot structure suitable for covering long distances because it is a ‘marathon hunter’. My response is that the hyena has to cover long distances because it is a scavenger, whereas the lion’s relatively smaller heart is because it is an efficient predator.
The contention that packs of hyena are normal and have always occurred is an assumption. Bill Harvey was a Game Ranger in Tanganyika (Tanzania) from 1928 to 1938. He writes “I traveled many thousand of miles by car, on foot and by canoe to cover my new range making careful notes containing detailed observations of all wild life in the provinces”. Harvey’s description of hyena is that of a scavenger: “they are heavily built animals with very strong shoulders and necks. Their skulls are wide and deep and their powerful jaws equipped with muscles and molars capable of crushing almost any bone excepting the biggest bones of an elephant . . . In spite of their size, strength and powerful jaws, they seldom attack any living creatures bigger than themselves and then only if the victim is asleep or sick... They are solitary and nocturnal in their habits ... Being cowardly creatures they live almost entirely on carrion ... No matter what state of decomposition of a carcass they will return night after night until every bit of rotting meat is eaten and then they will break up and eat the bones ... As a rule they do not hunt in packs and I have never come across an instance of this nature... They travel long distances in a night.”
The 1964 edition of Collier’s Encyclopaedia states that the hyena is a carrion feeder; that it is a solitary roving animal and that a large percentage of its food is from kills by lions; but no hyena would dare approach until the lion had satisfied its hunger and left the kill. Since the 1970's our concept of hyena has changed from the above description to believing that what we now see in these recent wildlife films is normal behavior.
How long is it going to be before logic prevails and effective conservation of Africa’s true predators begins? It will not be sufficient to merely stop feeding hyena through culling, poaching and hunting, or by safari camps that feed them their leftovers. It is my contention that, through controlled hunting/culling of hyena, and returning them to a scavenging role, populations of prey species will recover in a very short time and the predator populations will follow.