Paul Ehrlich (Bing Professor of Population Studies and Professor of Biological Sciences, Stanford University) and Anne Ehrlich (Senior Research Associate, Department of Biological Sciences, Stanford) are familiar names to ecologists and environmentalists everywhere. But while most folks are aware of the Ehrliehs' popular writing in the areas of ecology and overpopulation (most of us, for instance, have read Paul's book The Population Bomb), few people have any idea of how deeply the Ehrlichs are involved in ecological research (the type that tends to be published only in technical journals and college texts). That's why we're pleased to present this regular semi-technical column by these well-known authors-ecologists-educators.
In the last three columns, we've seen how resources are partitioned among the wild herbivores of the Serengeti ecosystem. Kenyan wildlife biologist David Hopcraft, along with his wife, Carole, has used such knowledge to launch a successful "game ranch."
Though cattle are viewed as a source of wealth by many African peoples, such as the Masai, the animals are—from an ecological point of view—actually a source of poverty in hot, semiarid climates. Cattle (and goats and sheep) must walk daily to a water supply to drink. This passage consumes a good deal of energy and slows the rate at which the animals gain weight. It also results in the trampling of valuable grasses and compacting of the soil surface.
On the other hand, wild herbivores have much less need to drink. Some, such as eland, oryx, and Grant's gazelles, may even obtain all the water they require from the vegetation they eat. Others drink some water but still need much less than do cattle. This is because most native African herbivores conserve water much more efficiently in digestion. For example, nearly all of the moisture is extracted from the intestinal contents of gazelles, and dry feces are released.
Cowpats, in contrast, are produced moist, and rapidly lose ammonia (and thus the vital nutrient nitrogen) to the atmosphere. They then dry in the sun and heat up, killing the bacteria and fungi that might speed their decomposition. The flat, dried cowpat even kills the grass beneath it!
The dry fecal pellets of antelope, however, are roughly spherical. They fall between the grass blades, do not heat up, and retain their nitrogen. Rather than tending to create a "fecal pavement," as cattle droppings do, they break down readily and return nutrients to the soil.
Moreover, like most grazers, cattle have quite specific food preferences—they graze some grass species heavily and others not at all. In cattle-raising areas, the species composition of the forage changes, with those grass species not eaten by cattle becoming increasingly common. But, as we described in our first column on the Serengeti ecosystem (MOTHER EARTH NEWS N0. 91), the native herbivores partition the available plant species, their diets complementing each other to one degree or another.
Thus, not only are the water-conserving native herbivores better adapted to the semiarid habitat of the African savanna, but they don't degrade it physically or chemically. Cattle, however, parading back and forth to water holes and producing their destructive droppings, have been a major engine of desertification on the continent.
All of these differences led David Hopcraft to conclude that the soundest way to exploit African grasslands is not to graze cattle on them, but to organize ranches to raise and harvest native herbivores. On their 20,000-acre ranch on the Athi Kapiti plains near Nairobi, the Hopcrafts have been putting that theory into practice since 1978.
Ecological Costs of Exotic Livestock Grazing
The ranch is stocked with a variety of grazers and browsers, including antelope, zebras, giraffes, and ostriches. Cattle are being phased out and may one day be replaced by African buffalo. For the present, however, the cattle serve as a valuable "control" for comparing costs and meat yields with those of the native animals.
A great deal of research is being carried out at the ranch. The dynamics of the various populations are carefully tracked, and the food preferences of the different animals are recorded. When we visited the Hopcrafts in early 1984, two veterinarians were at the ranch studying the parasites of harvested animals.
So far, the results of the experiment are exceeding the Hopcrafts' early hopes and expectations. The herds of native herbivores—and the meat yields from them—have been steadily increasing. Simultaneously, the condition of the range has been improving—even though the combined weight (biomass) of cattle and native herbivores has increased by some 35% in the past few years.
Harvesting is efficient and more humane than in a typical slaughterhouse. One night each week, men in Land-Rovers spotlight surplus male animals and dispatch each one instantly with a high-velocity bullet to the brain. The other animals are not distressed. Then each carcass is rapidly processed under the scrutiny of the government inspector.
The Hopcrafts are also experimenting with various ways of marketing the meat, which they describe collectively as "African venison." Having eaten steaks from many African herbivores, we can testify that when the animals are properly slaughtered and the meat carefully prepared, such food is delicious. We tried several new dried "jerky" products at the ranch and quickly became addicted to them. The venison is also being smoked and converted into sausages and salamis.
Multiple Advantages of African Game Ranching
It seems to us that the Hopcrafts have established the basic economic feasibility of African game ranching. Costs are substantially lower than those of cattle raising in that region. Much less water has to be supplied to the animals, meaning less capital must be sunk into bores, dams, and piping. And, unlike cattle, game animals require no dipping or inoculation against parasites and diseases.
Moreover, there is no need for herding or corralling—the native herbivores handle their own predator protection. Indeed, the Hopcrafts' herds have been expanding in spite of almost no predator control. Lions, cheetahs, hyenas, and jackals all inhabit the ranch, but they harvest only a small share of the game.
The exact economic advantages of a game ranch over a cattle ranch have not yet been determined. From the data the Hopcrafts have gathered so far, it appears that the yield of lean meat from an operation such as the game ranch will be at least twice the poundage per acre taken from the best cattle ranch in the region.
In addition to rapid growth rates in the game species, a major reason for this higher productivity is that a variety of herbivores partitioning resources can utilize much more of the vegetation than cattle can.
An additional advantage of the game ranch is in the potential for selling the hides. Those from the game should have a much higher value than cowhides, but at the moment the sale of game hides is prohibited by the Kenyan government—quite properly, since most of them are obtained by poaching. It is possible that a licensing system could be devised to allow game ranchers to market their hides, as mink ranchers do in the United States.
There are, of course, some problems still to be overcome. The main difficulties involve breaking traditions—traditions of what meat is good to eat, traditions among scientists in animal husbandry for whom the idea of game ranching is too novel, traditions among African pastoral peoples such as the Masai, to whom cattle are the main symbol of wealth.
In Africa, however, the benefits of breaking with these traditions would be enormous. In the face of extremely rapid human population growth, African game animals are fast disappearing; even national parks are under intense pressure from expanding agriculture and poaching. And hunger is already widespread on the continent, which has been stricken by disastrous droughts and famines in the last few years. Food supplies per person in most African countries south of the Sahara desert declined by about 10% between 1970 and 1982, as population growth outstripped the gains in food production. As the current drought has deepened and spread, food production has plummeted by another 10%. A major contributing factor to this continent—wide tragedy has been desertification caused in significant part by overgrazing of semiarid lands by traditional domestic animals.
Clearly, game ranching could help preserve Africa's unique large animals and contribute substantially to its food supply—if it can become established before desertification is too far advanced even to support the game animals. We're happy to report that the Kenyan government is very interested in the Hopcrafts' project, and that more game ranches may be established in that nation and elsewhere in Africa in the near future. The Hopcrafts' ranch has been serving as a training ground for interested students taking degrees in wildlife management and animal husbandry. These students will eventually be able to apply what they've learned to new projects.
Indeed, the Hopcrafts are now looking to the establishment of a game ranch utilizing North American herbivores -deer, antelope, American bison-in New Mexico, where overgrazing of cattle has led to considerable desertification . In view of its potential for being an ecologically benign, sustainable, and productive system of food production in any climatic region, we hope that game ranching is an idea whose time has come.
People interested in the New Mexico game-ranching project can get information by sending a self-addressed, stamped envelope to US, Inc., Petosky, MI.
The Ehrlichs' work is supported in part by a grant from the Koret Foundation of San Francisco.