摘要:

SummaryThe ovaries of five Günther's dik‐dik were investigated using histological techniques. The structure of the ovary and corpus luteum as well as the growth and atresia of the follicles are describ

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00120.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryAerial surveys from 1970 onwards suggest a stable Kafue lechwe population of 94 000±9% on the Kafue Flats. The present distribution shows a contraction in dry and wet season range in comparison with 1953/54.Sex ratios of populations on both the North and South banks of the Kafue river do not differ significantly from unity. North bank males have a higher survival rate than South bank males. Survival curves for males and females on the South bank show the same pattern. For both the 1971 and 1972 breeding seasons 73% of South bank females older than 1½ years are expected to have bred successfully. The peaks of conceptions for both seasons are from mid‐December to mid‐March, suggesting a main lambing period from mid‐July until mid‐October. Present sex ratio, age structure, reproductive status and the reproductive cycle have been compared with 1961/62 data.Variation in physical condition, based on monthly measurements of the kidney fat percentage, dressing‐out percentage and live weight, although influenced by the physiological demands of rut and pregnancy, is correlated with the availability of flood‐plain grazing. The lowest values of condition parameters are found during the period of maximum flood, after the end of the rains (April/May), until the receding flood makes flood‐plain grazing available, usually in early June. A high level of tuberculosis, lungworm infection and many other pathogens amongst the South bank population are reported. Animals from the North bank are thought to be in better physical condition.The Kafue Gorge dam, completed in 1971, and the Iteshi‐teshi dam, at present under construction, will prolong the high flood period in wet years and prevent most flooding in dry years, both of these effects will reduce the carrying capacity of the flood plain for lechwe and a large reduction of the size of the population is expected to result from the oper

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00121.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryElephant density over 40 000 km2of the Luangwa Valley was estimated as 2–17 km‐2to give a population size of around 86 000 in that area, a tally that would probably top 100 000 if unsurveyed areas within the drainage had been included. Seasonal movement is largely restricted to a migration on to the riverine strip during the wet season and reciprocal dispersal across the valley thereafter. The mean annual range of movement is about 25

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00122.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryBushbuck density, activity cycles, and ranging patterns on the Mweya Peninsula have been determined by continuous observation of individually recognizable animals. Individuals were followed for periods of 2 to 12 h, and observations were continued at night with the aid of a Starlight Scope image intensifier.The density of this population of bushbuck is very high compared to those reported using more standard censusing techniques. Home range size is larger (15‐3‐35‐2 ha) for adult and subadult males than for females and immatures. Sex ratios show a preponderance of adult females, as has been reported for other populations.Contrary to most published accounts, these bushbuck are no more active at night than during the day; rather, they exhibit cycles of activity with a periodicity of 2–5 h. A crepuscular peak of movement is, however, apparent. Examination of individual home ranges and of ranging patterns indicates that this crepuscular activity peak is connected with a complete disjunction of areas utilized at night and during the day. Bushbuck move out of thickets into patches of grassland at dusk, returning to thickets before dawn. Other differences between nocturnal and diurnal activity include an increase in the relative amount of grazing at night. Possible reasons for these phenomena, in particular the probable role of predation, are di

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00123.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryData on the monthly distributions of the Serengeti migratory wildebeest population between June 1960 and May 1973 have been analysed.It has been shown that the population performs an annual migration, spending the wet season on the Serengeti plains, then moving west towards Lake Victoria at the beginning of the dry season, and later north to the northern extension of the Serengeti National Park or into the Masai Mara Game Reserve in Kenya. The wildebeest return to the plains as soon as the rain begins, but if this is delayed they may move south‐west from the northern areas into the corridor first.Annual differences in the pattern of the migration can be correlated with differences in rainfall. The rainfall affects particularly the timing of the movements of the wildebeest on and off the plains, and the extent to which they utilize the northern areas.A large increase in the size of the population over the years studied has resulted in a greater utilization of the northern areas.It has been shown that about half the total range of the wildebeest population is outside the boundaries of the Serengeti National Park, and it is therefore important that these areas should be protected if such a large population is to surviv

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1975.tb00124.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY