摘要:

Summary(1) The activities of bull elephants in the vicinity of the Serengeti National Park headquarters at Seronera was monitored from 1968 to 1971.(2) Elephant bulls congregate in small groups of ever–changing composition; a dominance heirarchy cuts across group integrity.(3) Occupancy of the drainage area of the Seronera river is predictable by rainfall; changes in occupancy level are a question of duration rather than amplitude.(4) The feeding behaviour of the bulls is described. It is argued that largeAcaciatrees are uprooted for nutritional rather than social reasons. The effects of the bulls on the Seronera woodlands will be analysed in Part II (Croze, 1974

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00104.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Summary(1) The impact of groups of bull elephants on the wooded–grassland of the Seronera area of the Serengeti National Park, Tanzania, is examined.(2) Elephant use of trees occurs contagiously. At use loci in the woodlands, removal of canopy–forming acacia has been as high as 6% per annum.(3) However, from a survey of the whole Seronera woodland community, the loss of large trees has been 2–5% per annum.(4) It is argued that the regeneration potential is adequate to compensate loss due to elephant activity, and that large acacia will not disappear because of elephants.(5) Management action is discussed and recommendations

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00105.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryAn attempt was made to determine the species composition, density and biomass density of lizards in some of the principal land units in South Turkana. Thirteen species were recorded. Density estimates were determined from quadrat sampling in representative habitats.Because the number of lizards active was found to vary with time of day and temperature, minimum density estimates were obtained by confining counts to peak activity periods. Biomass density was calculated from the product of species density and the mean population weight measured from shot specimens. The biomass density estimate of the lizard fauna was found to be about 4–5% of the large mammal fauna, and appreciably more in the more arid land units.The species composition of South Turkana lizards show affinities to the Somali fauna, though not to the extent of the East Rudolf fauna, suggesting a more recent penetration of arid–adapted spec

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00106.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryObservations are presented on food searching in griffon vultures. To locate food directly, griffon vultures do not use a sense of smell but rely on vision. However, most birds locate carcasses indirectly—by watching the activities of neighbouring birds. The method of food searching is described and the number of birds which arrive at a carcass is shown to depend on the amount of food that is available. Birds do not hold feeding ranges, but travel widely during food searching, one bird travelling 180 km in 6 days. The density of searching birds varies greatly according to the density of ungulates in an area, birds being most numerous over high ungulate concentrations. The altitude at which birds search also varies, birds flying at higher altitudes over areas of low ungulate density and at lower altitudes over ungulate concentrations. These variations in searching density and height are shown to affect the efficiency of food searching. Carcasses are located rapidly and the food consumed quickly in high ungulate density areas, while in low ungulate density conditions carcasses can take a long time to be located. It is concluded that griffon vultures are more likely to find food and are better able to compete with mammalian competitors by searching over migratory ungulate herds than over areas containing resident ungulate species. Their adaptations for gliding flight enable these birds to follow these migratory ungulates throughout the yea

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00107.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00108.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00109.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00110.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY