Population estimates, densities and biomass of large herbivores in Simanjiro Plains, Northern Tanzania

Abstract

Summary A total of twenty‐four aerial censuses were carried out in the Simanjiro Plains, northern Tanzania, from 1970 to 1972 in order to estimate the populations, densities and biomass of eleven common large herbivores. Results show that amongst wild herbivores zebra and wildebeest have the highest populations which reach a peak during the wet season between March and May. They were estimated to be about 6000 and 5000, respectively. The corresponding densities were 10.96/km2 and 7.44/km2, respectively. There were practically none of these species in the area during the dry season. Figures for the other species are given. Cattle have the highest population which reaches a peak during the dry season. It was estimated to be about 26,000 with a corresponding density of 44.83/km2. The average total biomass density for all herbivores was 8500 kg/km2. RÉSUMEÉ Un total de 24 recencements atriens furent menés dans les Plaines du Simanjiro, en Tanzanie du Nord entre 1970 et 1972, en vue d'estimer les densités et biomasses des populations de 11 grands herbivores communs. Les résultats montrent que, parmi les herbivores, le zèbre et le gnou ont les populations les plus élvées, qui atteignent un maximum durant la saison des pluies entre mars et mai. On a estimé ces populations à 6000 et 5000 respectivement. Les densités correspondantes sont de 10,96/km2 et de 7,44/km2 respectivement. 11 n' y a pratiquement aucune de ces espéces dans la région durant la saison sèche. Les résultats concernant les autres espèces sont donnés. C'est le bétail qui a la plus haute densité de population, atteignant un maximum pendant la saison séche. II a été estiméà environ 26.000, correspondant à une densité de 44,83/km2. La biomasse moyenne totale pour tous les herbivores est de 8500 kg/km2.

Post Drought Population Status and Trend of Specialized Browsers in the Mid Kenya-Tanzania Borderland

“…They are also found west and south to Mkomazi, Amboseli and sporadically appearing in Serengeti National Park [2], and are probably extinct in Uganda, Sudan and Eritrea [1]. They inhabit scrubland, Acacia woodlands and semi-arid grasslands [5], and are mostly common in areas with an annual rainfall of 40 to 80 cm [16 to 31 inches]. Predictions [4] indicated that in the near future, the species is likely to be confined in protected areas as a result of pressure associated with habitat loss and illegal poaching outside these areas.…”

“…Their habitats are mostly semi-arid Acacia-Commiphora thornbush, and tend to avoid open areas and those with long grass [1] [2] [3], although they have been at about 1740 m near Mt. Kilimanjaro in Tanzania [1] [5]. It's a water independent species and primarily selective browsers, and forages on leaves and young shoots of shrubs, herbs and trees [1], and in a study in Tsavo East National Park, Kenya, [3] observed that they fed on 150 different plant species.…”

Assessment of distribution patterns for the grey kangaroo within southern Queensland : an application and appraisal of faecal pellet counts and aerial survey for the study of grey kangaroo density and distribution

“…In common with all sampling methods, once a critical sample size is reached, gains in precision are minimal and further sampling is of no great benefit unless the survey has aims additional to a population estimate. For example, while a sampling intensity of 25 per cent may be appropriate for an area of 570 km2 (Kahurananga, 1981) it is doubtful whether it can be justified for an area of 45 000 km2 (Fuller, 1950). With regard to kangaroo surveys, Caughley (1979b) discusses the role of size of the survey zone in determining sampling intensity.…”

“…Buechner et al, 1951;Bowman, 1955;Gilbert and Grieb, 1957;Darling, 1960;Lamprey, 1964;Watson and Turner, 1965;Lovaas et al, 1966;Buss and Savidge, 1966;Field, 1971;Eltringham, 1977;Edroma, 1981; and sample censuses (e.g. Fuller, 1950;Petrides, 1953;Banfield et al, 1955;Schultz and Muncy, 1957;Bergerud, 1963;Watson et ai., 1967;Kahurananga, 1981). Even where blocks are searched transects are usually the method utilized within each unit (e.g.…”

“…An aircraft altitude of approximately 9 0 m is the most widely used and recommended (e.g. Buechner et al, 1951; Petrides, 1953; Grzimek and Grzimek, 1960;Frith, 1964; Newsome, 1965;Bailey, 1971; Le Resche and Rausch, 1974; NortonGriffiths, 1975a;Kahurananga, 1981). The absolute range is from approximately 30 m to 600m (Fuller, 1950).…”