David Western

Natural connections : perspectives in community-based conservation

Both realism and justice demand that efforts to conserve biological diversity address human needs as well. The most promising hope of accomplishing such a goal lies in locally based conservation efforts -- an approach that seeks ways to make local communities the beneficiaries and custodians of conservation efforts.Natural Connections focuses on rural societies and the conservation of biodiversity in rural areas. It represents the first systematic analysis of locally based efforts, and includes a comprehensive examination of cases from around the world where the community-based approach is used. The book provides: an overview of community-based conservation in the context of the debate over sustainable development, poverty, and environmental decline case studies from the developed and developing worlds -- Indonesia, Peru, Australia, Zimbabwe, Costa Rica, the United Kingdom -- that present detailed examples of the locally based approach to conservation a review of the principal issues arising from community-based programs an agenda for future action

Life history patterns in birds and mammals and their evolutionary interpretation

SummaryIt is argued that allometric principles account for most of the observed variation in the life history patterns amongst birds. To test this contention it is shown that traits such as incubation time, growth rates, age at first reproduction, lifespan, clutch weight and egg weight all scale to body weight with exponents similar to those found for analogous traits in mammals. It is then shown that most of the variation amongst bird taxa and between birds and mammals based on body weight allometry can be explained by variations in brain size, body temperature and metabolic rate, consistent with theories of growth and ageing derived from mammalian studies. Finally, it is suggested that the evidence for life histostory allometry is sufficiently strong that it argues for a more epigenetic view of life history patterns and their evolution than is generally conceded in most adaptation theories.

Environmental Aspects of Settlement Site Decisions Among Pastoral Maasai

Maasai settlements in Amboseli are distributed in a pattern which reflects various physical and biological characteristics of the landscape. The settlements avoid hillslope gradients exceeding 0.08, and the lower sections of long hillsides, which receive large amounts of runoff. Long, relatively high hillslopes are difficult for exhausted cattle to climb at the end of the dry season, and even the welldrained sites at the upper ends of these slopes are not commonly used. Deep, poorly drained, and light-colored soils are avoided because they affect the comfort of humans, and especially the milk production of cattle. The settlements are located away from dense tree and bush vegetation because of the danger of predators, but during occupation of the site important changes in the vegetation are wrought by the use of trees for settlement construction and firewood. The reasons for the pattern were elucidated by making a set of systematic measurements of settlement distributions and various environmental factors. The conclusions of this analysis were then checked and extended through conversations with Maasai elders. These latter exhibited a sophisticated knowledge of environmental characteristics and processes which is reflected in their choice of settlement sites. Such knowledge has commonly been overlooked by other writers on the subject of pastoralism.

Cattle and Pastoralism: Survival and Production in Arid Lands

Traditional subsistence pastoralists in East Africa tend to keep large herds, milk cattle in preference to eating them, and subject them to long foraging treks. Such practices are widely considered ill-suited to arid lands and are believed to arise because cattle are raised more for social prestige than food production. Whether this is true can only be judged by considering the responses of cattle to arid zones and, given the herders goals and options, his management practices. In considering these factors, we show that indigenous East African cattle demonstrate energy-sparing capabilities during drought. Pastoralists can therefore herd cattle at great distances from water at little more cost than animals on the normal maintenance diet and watered more frequently. The physiological response of cattle to drought, the ecological constraints imposed by livestock and wildlife competition, and the energetic efficiency of mixed milk and meat pastoralism explain why herders traditionally select their characteristic management practices.

Africa's elephants and rhinos: Flagships in crisis

Despite extensive conservation measures over the last two decades, populations of elephants and rhinos in Africa continue to decline. The plight of the black rhino is especially acute. Poaching for rhino horn and ivory, rather than habitat loss, remains the principal threat to these species. The only long-term hope may lie in the effective protection of small, isolated populations.

Cattle Colors in Pastoral Herds: Natural Selection or Social Preference?

Indigenous cattle in East Africa show a wide range of coat colors. A study was undertaken to establish whether the observed variations resulted from social preference of herdsmen or natural selection. Cattle of different coat colors were compared under experimental conditions at 1,400—m altitude. Dark cattle absorbed more solar radiation than light cattle, drank more H2O, lost less weight during a drought, and gained weight faster after it. In the same drought, significantly more light than dark cattle died in an adjacent pastoral area, whereas in a lowland area more dark than light apparently do so in droughts. From a geographic analysis cattle colors were found to vary, with an increased proportion of dark animals at higher altitudes. However, cattle herds in northern Kenya were found to have a higher proportion of light cattle than at comparable altitudes in southern Kenya. When prevailing heat stress values were calculated, the proportion of light cattle was found to increase linearly with heat stress with no significant difference between northern and southern localities. The selective effect of heat stress on coat color is discussed. The trend line of lighter coat color with higher heat stress was found to operate within and between tribal boundaries. Social preferences apparently do not strongly influence the prevailing natural selective formce but may reinforce it as the ecological significance of coat color is widely recognized by pastoralists.

Grasslands, People, and Conservation: Over-the-Horizon Learning Exchanges between African and American Pastoralists

The worlds grasslands and large migratory populations of wildlife have been disproportionately lost or disrupted by human activities, yet are poorly represented in protected areas. The major threats they face are land subdivision and the loss of large-scale dynamic processes such as wildlife migrations and fire. The large-scale dynamical processes and ubiquity of livestock economies and cultures across the grasslands calls for an integrated ecosystem approach to conservation to make up the shortfall in protected-area coverage. Ranchers and pastoralists will be more inclined to adopt an integrated landscape approach to conservation if they also see the threats to wildlife and grassland ecosystems as affecting their livelihoods and way of life. We arranged a series of learning exchanges between African and American pastoralists, ranchers, scientists, and conservationists aimed at building the collaboration and consensus needed to conserve grasslands at a landscape level. There was broad agreement on the threat of land fragmentation to livelihoods, wildlife, and grasslands. The exchanges also identified weaknesses in prevailing public, private, and community modes of ownership in halting fragmentation. New collaborative approaches were explored to attain the benefits of privatization while keeping the landscape open. The African-U.S. exchanges showed that learning exchanges can anticipate over-the-horizon problems and speed up the feedback loops that underlie adaptive management and build social and ecological resilience.

PATTERNS OF DEPLETION IN A KENYA RHINO POPULATION AND THE CONSERVATION IMPLICATIONS

Abstract The Amboseli black rhino population has been monitored closely over 13 years and its decline to near extinction levels parallels its fate elsewhere. The patterns and causes of decline are attributed directly to human agencies, initially resulting from changing social and political circumstances amongst pastoralists, recently due to poaching for horns. The general conservation implications are discussed and the need to contain the international trade in horns is considered the overriding priority, due to the difficulty and expense of eliminating poaching.

Impact of Land Subdivision and Sedentarization on Wildlife in Kenya’s Southern Rangelands

Abstract Subdivision and sedentarization of pastoral communities is accelerating rapidly across the African rangelands, posing a severe threat to wildlife populations, but few studies have looked quantitatively at the ecological impact of sedentarization. Here we look at the impact of sedentarization on wildlife by comparing ecologically matched subdivided and unsubdivided Maasai pastoral lands (ranches) in semiarid southern Kenya. We found no significant difference in livestock densities on the two ranches but there was a significantly higher wildlife density on the unsubdivided ranch, in both dry and wet seasons. Nonetheless, the unsubdivided ranch still had a higher percentage of grass biomass and ground cover and lower grazing pressure than the subdivided ranch. Distribution of homesteads (bomas) was mostly random on the subdivided ranch, with little area unaffected by human settlement. On the contrary, the unsubdivided ranch had a highly clumped boma distribution pattern, resulting in much of the land being relatively far from permanent human settlement. We show that the regular distribution and permanence of settlements following subdivision and sedentarization greatly reduces wildlife populations both through direct displacement and a reduction of forage. Relative to mobile pastoralism on open rangelands, sedentarization leads to reduced seasonal movements of livestock, lowered grass biomass, and slower grass recovery after very dry periods. This study points to the need to maintain mobile, large-scale herd movements to avoid the heavy impact on grasslands associated with sedentarization of pastoral settlement and herds.

Production, reproduction and size in mammals

It is argued that birth rate, turnover rate and production/biomass ratios (P/B) are equivalent in stable populations. It is then shown from field data on 21 mammal species that production scales as a 2/3 power of body mass, suggesting that size rather than life history characteristics explain most interspecific variation. The relationship simolifies calculations of annual production in populations and energy flow through communities.