Potentials and problems of wildlife ranching
A Kenyan wildlife ranch
Model calculations
Conclusions
Bibliography
H. Fink and R. BaptistThis article is based on work carried out at Dr D. Hopcraft's ranch (Wildlife Ranching and Research Ltd) in collaboration with its director of research, Dr M. Sommerlatte. We are grateful for all assistance, guidance and hospitality received. Thanks are also due to the Eiselen Foundation for the financial support arranged through the Centre for Tropical Agriculture at the University of Hohenheim. The authors' addresses are: Institute of Animal Production in the Tropics and Subtropics, University of Hohenheim, D- 7000 Stuttgart 70, Germany, and Department of Animal Production, University of Nairobi, PO Box 29053, Kabete, Kenya, respectively.
In regions where the rainfall is too low for crop production, the conversion of herbage biomass by animals yields highly valued products In the hostile conditions of Africa's dry lands livestock is reared with difficulty, with occasional harmful effects on the range environment. Mixed wildlife species use different feeding strata - i.e. grass, fortes, shrubs and trees - than cattle do, and thus secure higher overall efficiency.
Many antelope species are very astute in selecting high-quality plant parts. Some feed mainly at night, when the water content of forage is higher than it is during the day. Physiological survival mechanisms such as increased body temperature or reduced water loss should also be mentioned here. Some species tolerate a body temperature of 45°C for up to six hours without harm. Wild ungulates are tolerant of such diseases as trypanosomiasis, theileriosis and foot-and-mouth disease and of external parasites such as ticks. The meat quality and the dressing percentage of their carcasses are reported to be superior to those of domestic ruminants and they contain less fat. These comparative advantages have drawn attention to wildlife ranching as an economic activity (Ledger, Sachs and Smith, 1967; King et al., 1975; King, Heath and Hill, 1977; King et al., 1978; Field, 1972, 1975, 1979; Lewis, 1977; Hoogestein-Reul, 1979; Walker, 1979; Hopcraft, 1980; Sommerlatte, 1990; Talbot and Talbot, 1963; Talbot et al., 1965; Kay, 1970; Ledger, 1983).
Wildlife ranching has been perceived as a low-input form of land use, requiring fewer watering facilities, veterinary treatments or mineral supplements than livestock ranching, if any. It also has a range conservation potential. However, the potential of wildlife resources is not only determined by superior ecological adaptation mechanisms, but also by managerial and socio-economic forces. According to Kyle (1987), it can be difficult to find and organize a sufficiently broad commercial outlet for venison. The same author reports that some schemes have failed because of overcropping. One reason for this has been highly tentative predictions of herd productivity based on too short a study period.
In order to set cropping targets, the range and wildlife herds have to be monitored and their productivity narrowed down in terms of carrying capacity, stocking rate, sustained yield and cropping target. These complex and mutually dependent issues can only be approached by adaptive management rather than theoretical assessment. In other words, the determination of cropping targets is more an art than a science. However, even a very intuitive form of management (and administration) requires monitoring of animal numbers. Simple as it may seem, counting wild animals poses its own problems (Overtop and Davis, 1969; Eltringham, 1973; Norton-Griffith, 1978; Sinnary, 1988; Magin, 1989). As wild herds also require a critical number of mature and dominant males in order to maintain reproductive capacity, they must be monitored with regard to their structure as well. Counting and monitoring herds requires a certain level of management and inputs, which reduces the advantage of wildlife utilization as a low-input land-use scheme. This is, of course, all related to the sheer difficulties of herding, handling and culling animals, which are so straightforward with domestic livestock.
Attempts at wildlife utilization have taken different forms, including commercial, communal or cooperative ventures, running various combinations of venison cropping, trophy hunting and establishing wildlife parks for the purpose of tourism or conservation. A communal scheme funded by the United Nations Development Programme (UNDP) and implemented by the Food and Agriculture Organization of the United Nations (FAO) in Zambia was the Luangwa Valley Conservation and Development Project. These same agencies carried out a wildlife management project in the Kajiado district of Kenya, where cropping activities came to a halt in 1976 when the government banned all hunting of wildlife. In Zimbabwe (Style, 1990) and Namibia (Berry, 1990), wildlife ranching has become a widespread enterprise of mostly commercial ranches backed by national wildlife departments.
Only venison production was considered from among the various outputs and sideline enterprises of wildlife utilization for this study, which was carried out at Wildlife Ranching and Research Ltd (WRR), near Athi River, 40 km southeast of Nairobi, at an altitude of 1600 to 1700 m. The ranch covers a fenced area of approximately 8100 ha, with grass and bush as the prevailing vegetation. The average rainfall is 510 mm per year, with two annual peaks. Of the several wild ungulate species that are found there, the most important ones economically are Thomson's gazelle (Gazella thomsoni Günther), Grant's gazelle (Gazella granti Brooke), Coke's hartebeest or kongoni (Alcelaphus buselaphus cokii Günther), wildebeest (Connochaetes taurinus Burchell) and impala (Aepyceros melampus Lichtenstein). Other common species are zebra (Hippotigris quagga Gmelin), Masai giraffe (Giraffa camelopardalis tippelskirchi L.), oryx (Oryx gazella L.), common duiker (Cephalophus grimmia L.) and warthog (Phacochoerus aethiopicus Pallas). Cheetah (Acinonyx jubatus Schreber), spotted hyena (Crocuta crocuta Erxleben) and black-backed jackal (Cants mesomelas Schreber) are predators that intrude from time to time or that live on the ranch permanently in limited numbers.
Before 1981, WRR was managed as a normal cattle ranch. In order to implement the findings of Hopcraft (1975) on the comparative productivity of Thomson's gazelle and cattle, the ranch was licensed by the Kenyan Government to harvest animals from the wild herds within its perimeter. A prerequisite was the installation of a game-proof fence 2.6 m high and 50 km long to surround the ranch. A slaughterhouse with a meat processing plant and cooling facilities had to be constructed. Cropping is performed by dazzling animals with a spotlight at night, killing them with a shot to the head and then bleeding them on the spot. The purpose of WRR was to provide evidence that wildlife utilization is economically and ecologically feasible under the proper circumstances (Hopcraft, 1986). In addition to being a commercial venture, the ranch has been a research terrain for a great number of national and foreign workers, studying various aspects of wildlife biology and utilization.
From their studies transpired a conservative carrying-capacity estimate of about 40 kg wild herbivore live weight per hectare, taking into account the fact that the wild herbivores share the terrain with the ranch's stock of about 3000 beef cattle. In early 1990, the total number of wild herbivores of commercial value was estimated at 2035 head, equivalent to a biomass density of about 23 kg live weight per hectare, which is 58 percent of the estimated carrying capacity. The five main species examined in this report are wildebeest, hartebeest, Grant's gazelle, Thomson's gazelle and impala. They made up 13 kg/ha. In addition to the wild animals, approximately 2900 head of beef cattle and 300 Somali sheep were grazed, accounting for an additional biomass of 104 kg/ha.
The field work was carried out during two visits, from March to May 1990 and in November 1990. Herd structures of Thomson's and Grant's gazelle, Coke's hartebeest, wildebeest and impala were determined by direct observation and by comparison with an earlier study (Dani, 1985). In all species, a large flight distance of about 200 to 300 m was observed. When cropping started, Hopcraft (1975) reported the flight distance to be about 80 m for Thomson's gazelle. Another observed change in the animals' behaviour was the almost complete absence of bachelor groups. Only Grant's gazelles maintained some bachelor groups of notable sizes. Ranch statistics on cropping and the results of the total ground counts covering the nine-year period from 1981 to 1989 were compiled from annual ranch reports (Gubelman, Stelfox and Graves, 1989) and are reproduced in Table 1. Taking total ground counts of herd size is the best method available to the ranch, but it only provides estimates. Nevertheless, Table 1 indicates that herds have not increased markedly, if at all.
From the figures given above on the carrying capacity of wild herbivores, the current stocking rates and the realized herd expansion rates, it is clear that the ranch is understocked with wild herbivores. Therefore, for the purposes of herd dynamics modelling, it can be assumed that the animal-inherent parameters of survival and reproduction are the same over a wide range of herd sizes and stocking rates, i.e. the possible effect of density-related feedback can be excluded. Herd dynamics are determined by animal-inherent productivity components on the one hand and by the management-imposed cropping regime on the other. The former comprise mortality rates, age at first parturition, parturition intervals and litter sizes. The cropping regime consists of the percentage of "mature" animals of both sexes harvested each year.
The microcomputer package PRY (Baptist, 1990) was used to simulate a cropping regime where only "excess" males are harvested, while all females are allowed to breed until they die of natural causes. For this regime, the amount of time taken by present herds to expand to a size corresponding to carrying capacity, i.e. to double, was determined. At target population sizes, the sustained offtake was determined, assuming that excess males and females are harvested at an age corresponding roughly to the species' average age at first parturition. Such a regime is not feasible for all species or cropping schemes as it requires the reliable ageing and sexing of those animals to be harvested. The estimated sustained offtake rates, therefore, represent maximal yields. This is acceptable, however, since sex- and age-discriminatory cropping at the stationary state affects the yield only very slightly (Baptist and Sommerlatte, 1991).
For the model calculations, parameter estimates for litter size, age at first parturition, parturition intervals and maximum age of the animals were set to average levels as reported in the literature. Mortality rates and the rate of female cropping were varied until the herd productivity, calculated on the basis of the assumed parameters, closely simulated the estimates of realized productivity in Table 1 (for details, see Fink, Sommerlatte and Baptist, 1991).
Results indicated that herds at WRR have remained stationary because females have been cropped intensely (Table 2). If females had been allowed to die of natural causes only, herds could have increased by 15 to 30 percent per year (Table 3). These are theoretical equilibrium rates only, which will stabilize with time if all females are allowed to breed freely. However, initial growth rates for specific seed herds can differ from these expected values, which is why the time required for the expansion of present herds to target size was determined by simulation. When cropping was completely suppressed during expansion, the herds needed 51 to 80 months to reach their target size, depending on the species. When excess males were culled during herd expansion, the populations required 59 to 101 months to attain their target, but during this time an annual male offtake of 7 to 14 percent of herd size was possible. After reaching the target herd size, offtake ranged from 15 to 23 percent, depending on the species (Table 3). This does not compare very favourably with offtake rates of up to one-third for herds of domestic small ruminants which include very few mature males.
1 Realized offtake and herd growth at Wildlife Ranching and Research from 1981 to 1989
Prélèvements réalisés et croissance des hardes au ranch de la Wildlife Ranching and Research entre 1981 et 1989
Entresaca realizada y crecimiento de los hatos en el Wildlife Ranching and Research entre 1981 y 1989
|
Game species |
Annual offtake rate1 |
Females in % of crop |
Herd growth (% per year)2 |
|
Thomson's gazelle |
23 |
34 |
- 9 |
|
Grant's gazelle |
17 |
36 |
- 6 |
|
Hartebeest |
26 |
43 |
- 6 |
|
Wildebeest |
213 |
38 |
8 |
|
Impala4 |
15 |
17 |
17 |
1 Relative to maximum ground counts following the proposition of Sinnary (1988).
2 Calculated from the relative growth multiplier for the period considered raised to the power of the reciprocal of period length.
3 Exclusively in 1985.
4 Impala cropped since 1982.
2 Implied mortality and female cropping rates at Wildlife Ranching and Research
Taux supposé de mortalité et de prélèvement de femelles au ranch de la Wildlife Ranching and Research
Mortalidad implícita y tasas de extracción de hembras en el Wildlife Ranching and Research
|
Game species |
Annual mortality rate (%) |
Rate of females cropped | |
|
|
Calves |
Other ages |
per parity (%) |
|
Thomson's gazelle |
45 |
22 |
10 |
|
Grant's gazelle |
40 |
10 |
15 |
|
Hartebeest |
20 |
5 |
25 |
|
Wildebeest |
20 |
5 |
24 |
|
Impala |
30 |
10 |
7 |
3 Potentials of herd growth, male cropping rate during expansion and sustained offtake at Wildlife Ranching and Research
Potentiels de croissance des hardes, taux de prélèvement des mâles pendant l'expansion et taux d'exploitation durable au ranch de la Wildlife Ranching and Research
Potencial de crecimiento de los hatos, tasa de extracción de machos durante el período de expansión y entresaca sostenida en al Wildlife Ranching and Research
|
|
Potential rate of increase of herd size (% per year) |
Males cropped during herd expansion (% of herd size per year) |
Sustained offtake (% of herd size per year) |
|
Thomson's gazelle |
15 |
14 |
22 |
|
Grant's gazelle |
16 |
7 |
15 |
|
Hartebeest |
30 |
8 |
21 |
|
Wildebeest |
22 |
7 |
19 |
|
Impala |
26 |
9 |
23 |
Impala (female) - Impala (femelle) - Impala (hembra)
Impala (male) - Impala (mâle) - Impala (macho)
Grant's gazelle (female) - Gazelle de Grant (femelle) - Gacela de Grant (hembra)
Grant's gazelle (male) - Gazelle de Grant (mâle) - Gacela de Grant (macho)
Thomson's gazelle (female) - Gazelle de Thomson (femelle) - Gacela de Thomson (hembra)
Thomson's gazelle (male) - Gazelle de Thomson (mâle) - Gacela de Thomson (macho)
Wildebeest (female with calf) - Gnou (femelle avec son petit) - Ñu (hembra con una cría)
At WRR, the sustainable cropping rate of wild herbivores did not seem outstanding when compared with that expected for livestock, especially small ruminants. However, such comparisons across species are quite meaningless for several reasons. Most important, the question is never one of substitution but, rather, one of complementarily. Furthermore, outputs cannot be rated in physical terms but must be valued. In general, venison fetches substantially higher prices. On the other hand, wildlife utilization is not a zero-input scheme. In fact, cropping wild animals is more costly than culling livestock. Another aspect is the far greater opportunities for diversification offered by wildlife; venison is just one output. Others include trophies, souvenirs, furs, photo motives, tourist services or sideline recreational activities. Technical arid economic determinants of productivity, therefore, seem to be more crucial than biological differences between wild and domestic animal species. Issues of biological efficiency become more important where a difficult environment is a permanent or sporadic feature. Wild animals can withstand harsh conditions better than domestic livestock. The edge that livestock certainly has over the wildlife resource involves an aspect of the non-biological environment: the knowledge base of its management and utilization is huge. If only a fraction of the resources that have gone into livestock research worldwide were being invested in research on wildlife resources, the conclusions on the comparative productivity of livestock and wildlife would certainly experience appreciable shifts.
The more practical conclusions of the present modelling exercise are as follows. At WRR, female animals ran a chance of up to 25 percent per parity (of which there are several in a lifetime) of being cropped during their reproductive life. In populations that are to be kept stationary, this is not a disadvantage. On the contrary, such a regime increases the sustained cropping rate because females are made use of before they die naturally. However, when the objective is to increase herd size, cropping of females must be counterproductive. At WRR, female cropping in combination with the high natural mortality rate has led to stagnant herd sizes. Cropping of females must also have accounted for part of calf mortalities. If cropping of females had been avoided, herds would have expanded quickly. Cropping of males during expansion could have yielded annual offtakes of 7 to 14 percent of (the steadily increasing) herd sizes. For Thomson's and Grant's gazelles and impala - where it is possible to determine the sex of animals to be cropped by the presence of horns and size and shape - the practice of excessive female cropping certainly brought about missed opportunities. Unfortunately, taking sex into account at the time of cropping is not feasible for hartebeest or wildebeest as they cannot be marked or segregated according to sex without unjustifiable input and expense. If corresponding techniques could be identified, the internal rate of return of venison production would likely increase by 50 to 250 percent (Baptist and Sommerlatte, 1991).
For venison producers, the substitution of species with clear sex dimorphism for those without is a strategy worth considering, especially in situations where herds have to be built up or where periodic population collapses are a regular feature of the environment.
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