ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00132.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryTemporal patterns of reproduction in nine species of ungulates were studied by means of repeated road strip counts and through observation of individually known females. Zebra and oryx show one distinct peak of births annually, Coke's hartebeest two peaks per year, but all these species may give birth throughout the year. In waterbuck, impala, Grant's gazelle, gerenuk, lesser kudu and giraffe no marked peaks were evident, i.e. reproduction is largely non‐seasonal. Only the warthog (though not studied in detail) has a short, distinct reproductive season. While mean rainfall and temperatures follow a well‐defined seasonal pattern, rainfall is often irregularly distributed, both in time and in space, and varies considerably from year to year. For most species, more or less continuous reproduction may therefore be more advantageous than a seasonal pattern related to average climatic conditions. Other factors influencing the temporal pattern of reproduction include phylogenetic relationships and food habits. Seasonal reproduction is more marked in grazers than in browsers, and this difference is probably related to seasonal changes in food qual

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00133.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryAnnual and monthly rainfall records (1969‐72) for the southern section of Tsavo National Park (East) were used to estimate net primary production above ground. Annual estimates of mean primary production varied between 210 g nr‐2a‐1(1971) and 545 g nr‐2a‐1(1969). The distribution limits of elephant deaths during 1970‐71 showed good correlation with the annual 200 g nr‐2a‐1contours.The calculated food consumption of the elephant population indicated txhat 4–7% of the primary production was eaten in years of good rainfall and 8–12% in drought years. Monthly food consumption was used to demonstrate that in a year where 4 to 5 consecutive months fell below the large mammal food requirement some mortality occurred.Maps showing the probability of a given level of primary production occurring in a specific region in any one month related very well to recorded elephant distributions. Further maps showing the probability with time of 4 and 5 consecutive months with primary production below the food requirements of the large mammals predicted 5 and 10 year and 43–50 year periodicities in primary production. The influence of the annual and longer term periodicities is discussed, and illustrated by generalized models which predict the ‘carrying capacities’ of the habitat for the different faunal categories.The potential of the probability maps for management purposes was demonstrated by reference to the ‘elephant problem’ and the much discussed recommendations of culling and non‐interference. On the available evidence it is believed that, in Tsavo (East), non‐interferenc

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00134.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryVegetation communities and the climate during the study are described for the ranch. From 1970 to 1972 feeding observations were made during 21 months on semi‐domesticated buffalo, eland and oryx and on cattle using the feeding minutes technique. The animals were observed in three plant communities as follows: (1) riverine vegetation with eroded slopes; (2) a catena of dry grassland and bushed woodland on grey and red soils; (3) moist coastal bush with grassland patches. Observations included periods of high and low rainfall in each community although these were irregular. Plant samples from the more common species were collected at intervals for chemical analysis.Early in the plant growth period all species graze within the grass/herb layer. As the grass matures eland gradually concentrate on browse plants while the other species continue to graze and to browse a little. When deciduous browse plants lose their leaves eland rely on evergreen shrubs.Annual and drought‐tolerant perennial grasses form the main diet of oryx while buffalo and cattle both eat bulky perennial grasses.Analyses of browse leaves show that during dry periods they are comparatively rich in protein when compared with grasses. The requirements of eland for protein rich food explain why they migrate over the ranch and do not do well when restricted. The possible influence of irregular rainfall on the eland population is discussed.The oryx is the smallest of the three grazers and therefore able to be more selective. The annuals which they eat form standing hay which is fairly nutritious, while their small mouths permit selection of protein‐rich parts of perennial grasses. Cattle and buffalo require large quantities of feed which may be of poor quality. Their large mouths are unable to select the protein‐rich parts of perennial grasses and this puts them at a disadvantage during a prolonged

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00135.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryThe stomach contents ofLemniscomys striatusandPraomys (Mastomys) natalensis, caught in the Rwenzori National Park over a period of one year (1965‐66), were analysed. InLemniscomysthe percentage by weight of insects (mainly termites) in the stomachs increased during the wet seasons, while termites were consumed byPraomysthroughout the year. Qualitative analysis showed that the fruits of the woody shrubErythrococcusformed an important part of the dietof Praomysduring the rains. Both species ate grass leaves and stems in varying amounts throughout the year and both utilized seeds of legumes and other herbs towards the end of the wet seasons.In bothLemniscomysandPraomyscollected between January and June 1972 liver and total body fat levels appeared to be related to rainfall and to reproductive state. There was a peak in fat levels during the high rainfall period in April. Pregnant and lactating females were caught mostly in May and June towards the end of the wet season; they had higher fat levels than males caught in the same period, but lower fat levels than non‐breeding mature or immature females and males caught in April.The possible significance of seasonal changes in diet and in body composition in the timing and duration of the breeding season is discus

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00136.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryEnvironmental influences on reproduction in female giraffe were investigated by calculating conception dates for 123 calves and twenty foetal giraffe from the eastern Transvaal, South Africa. Of these, 60% occurred during the 4 months December to March. This period is the peak of the austral summer when plant leaf production is at a maximum, the preferred food species of the giraffe are abundant and the protein and energy content of these are high. Rainfall is also highest at this time. Conceptions also occurred in all other months of the year. Data on calving from captive animals in Australia, and from wild giraffe elsewhere in South and East Africa were also included in the study. Nineteen adult male giraffe collected over a period of 1 year from the eastern Transvaal were also investigated. Seminiferous tubule diameter fluctuated with age but regular seasonal fluctuation was not apparent. Testicular testosterone concentration varied from trace amounts to 10.1 μg/g. Testes mass and epididymes mass were closely correlated with age but no seasonal effects were apparent

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00137.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryRanging patterns, feeding activity, and time budgets of a group of gray‐cheeked mangabeys in the Kibale Forest, western Uganda, were studied in May‐June 1971 and from March 1972 to April 1973. Locations and activities of individuals in a fifteen‐member group of this arboreal primate were systematically recorded at half‐hourly intervals during continuous following of the group. Phenological data were concurrently collected for eleven species of intensively used trees. Mangabeys are primarily frugivores, although leaves and flowers of some species are eaten and substantial time was devoted to insect foraging.Although a typical twice‐yearly alternation of wet and dry periods exists in this forest, strongly seasonal trends are the exception in the following aspects of mangabey behaviour: (1) extent and location of areas used, (2) distance moved daily, (3) percentage of time spent feeding or moving, (4) percentage of time spent feeding on different food types. An explanation may be provided by the phenological data, which indicate that many species of tree used by mangabeys fruit either asynchronously and nonseasonally or synchronously but at very long and possibly irregular intervals. Thus mangabeys are faced with foods which fluctuate widely in availability, particularly within a small area, but which are not seasonal in their flu

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00138.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryThe Amboseli ecosystem is in a semi‐arid savannah environment in which water availability is highly seasonal, a feature which has an important bearing on the structure and efficiency of the large mammal community.Data are presented to show that the seasonal movements, a wet season dispersal and dry season concentration of water‐dependent species (obligate drinkers) can be related to the seasonality of rainfall and water availability, but that similar patterns do not prevail in the water‐independent species.Evidence suggests that water availability is a crucial parameter in calculating the carrying capacity of a range, and that the duration of ephemeral supplies, which reflect rainfall seasonality, evapotranspiration, and soil water storage capacity, is equally important. A simplified model is presented which calculates the carrying capacity of water‐bound communities–taking into account these two limiting factors.There appears to be a physiological barrier to a heavy utilization of the low water content grasses beyond reach of the water‐dependent species, since most water‐independent species select high water content browse in order to maintain a positive water balance. Significantly, while the water‐independent community is almost exclusively composed of browsers, most water‐dependent species are grazers. The biomass density of large mammals beyond 15 km from water, a radius which encloses 99‐5% of the biomass of water‐dependent species, is extremely low compared to areas within 10 km of water.As a consequence of the physiological barrier to a heavy utilization of low water content forage in water‐deficient areas, the food chain efficiencies are appreciably lower than those with permanent water sources. Livestock development programmes have long appreciated this constraint and employed water development schemes to increase range‐carrying capacity.Seasonality in the movement patterns of Amboseli is compared to other large mammal communities and management i

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00139.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryMeasurement of total body water and water turnover was based on the single injection dilution principal using tritiated water.Under a daylight grazing regime the water turnover varied from 24 to 98 ml/kg/day in oryx and 42 to 121 ml/kg/day in eland. This large seasonal variation was most highly correlated with heat load expressed as solar radiation or mean ambient temperature. Lack of correlation between water turnover and dry matter intake, and low correlation with dietary moisture may have been due to difficulties in measuring these parameters accurately.When preformed water was calculated by subtraction of drinking and metabolic water from total turnover, it was found to have a positive correlation with turnover rate and a negative correlation with water drunk. Thus high water turnover was not associated with high drinking requirements in either species.The relationship between climate, pasture and water turnover, could be upset by changes in the activity of the animal from the normal day grazing pattern.The results obtained from the domestic game animals were used to explain how wild oryx and eland could exploit a hot, semi‐arid environment without drinking. To achieve this, the wild animal must obtain most of its nutritional requirements between evening and morning, and its water requirements during the period of maximum relative humidity between midnight and daw

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00140.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00141.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY