The giraffe and its food resource in the Serengeti. II. Response of the giraffe population to changes in the food supply
The dynamics of the giraffe population of the Serengeti were quantified to ascertain the response of the population to the increasing biomass of the available browse resource. Aerial counts conducted in 1971 and 1976 together with analyses of fecundity and mortality data suggest a rate of population increase of some 5-6% per annum. Compared with […]
Comparison of aerial counts with ground counts for large African herbivores
1. Over the past 50 years, aerial counts have been widely used in African wildlife management; however, the accuracy of the resulting estimates has rarely been questioned. The reliability of aerial counts of large African herbivores was examined by comparing the results of a series of systematic aerial sample counts with those from a series […]
A study of animal movement in the Hoanib River catchment, northwestern Namibia
Seasonal movements of domestic stock and wildlife were analysed across the Hoanib River catchment. Data were gathered by ground and aerial surveys and represent the seasonal movement of animals, rather than the total number of animals in the catchment area. Domestic stock movement and distribution did not vary substantially and appeared to be associated with […]
Giraffe demography and population ecology
Population dynamics describe temporal change in population size and structure and the processes that contribute to that change. For conservation to succeed, it is critical that we are able to detect changes in population size and the demographic processes in the population, and also we must learn how to effect change in population size by […]
Migratory herds of wildebeests and zebras indirectly affect calf survival of giraffes
In long-distance migratory systems, local fluctuations in the predator–prey ratio can exhibit extreme variability within a single year depending upon the seasonal location of migratory species. Such systems offer an opportunity to empirically investigate cyclic population density effects on short-term food web interactions by taking advantage of the large seasonal shifts in migratory prey biomass. […]
Precision, accuracy, and costs of survey methods for giraffe Giraffa camelopardalis
Giraffes Giraffa camelopardalis are megafaunal browsers and keystone species in African savanna ecosystems. Range-wide population declines are suspected, but robust data are lacking. Tanzania holds the largest population of giraffe of any range state, and aerial surveys constitute most of Tanzania’s giraffe population monitoring data, but their accuracy has not yet been assessed. An IUCN […]
Herbivore population crashes and woodland structure in East Africa
Between 1985 and 1991, bush encroachment was serious in Lake Manyara National Park, northern Tanzania. Shrub cover increased by c. 20%. The increase was independent of initial (1985) shrub cover. Since 1987 there has been a steep decline in the number of African elephant in the Park due to poaching. Elephant density decreased from about […]
Seasonal ungulate distribution and densities on Manyara ranch 2012-13
The northern Tarangire-Manyara Ecosystem in Tanzania is among the richest areas in the world for large mammal diversity and abundance, and Manyara Ranch provides crucial wildlife habitat for migratory and resident species between the Tarangire River and Lake Natron. This area is essential to the survival of migratory wildlife populations in the area, and sustains […]
The giraffe and its food resource in the Serengeti. I. Composition, biomass and production of available browse
The quantification of the browse resource available to giraffe was undertaken as the first stage in the study of the relationship of the giraffe population and its food supply in the Serengeti woodlands. Techniques are described for estimating the seasonal standing crop biomass of available browse and its quarterly rate of production. The conversion of […]
Densities of mammals in partially protected areas: the Katavi ecosystem of western Tanzania
In Africa the majority of conservation areas sanction some sort of human activities within their borders but few of them are part of community‐based conservation schemes. The effectiveness of these state‐owned, partially protected areas in conserving mammalian fauna is largely unknown. Large and medium‐sized mammal densities in three different sorts of partially protected area were […]