摘要:

SummaryAspects of the seasonality of breeding, age‐specific fertility, and growth were studied in a sample of animals collected from the Serengeti buffalo population, and compared with two populations in Uganda. Fluctuations in fertility and recruitment were studied by the use of regular aerial photographic samples of herds in the Serengeti. The fluctuations in fertility rate were not related to density and hence could not have regulated the population.Buffalo show a pronounced seasonality in births which is correlated with the quality of ingested food and with rainfall. Since the female has a considerably higher food requirement during late pregnancy and lactation, nutrition is probably an important factor determining this seasonality. Conception does not appear to be influenced by nutrition, for the quality of food remains high throughout the rainy season prior to and during the period of conception. Growth rate, age of first ovulation, and age of sexual maturity do not appear to differ between the Serengeti and Uganda populations. Although there is little difference in fertility between these populations, as measured from the collected samples, little weight can be placed on this evidence, for large fluctuations in fertility can take place from year to year within a population. The fluctuations in the Serengeti population do not appear to be correlated with rainfall, and it is possible that they are random. Fluctuations in recruitment from year to year are also observed. Two sample areas over 100 km apart but within the same population show parallel fluctuations suggesting a similar external influence on the size of the recruitment. This recruitment is not correlated with population size but it may be related to rainfall. Underweight calves at birth have been recorded and this may have been caused by the undernutrition of pregnant females during the dry season through a combination of poor food supply and the demands of the previous lactatio

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00111.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryAnalysis is carried out on the population data obtained from censuses and estimates of fertility and recruitment for the years 1965–1972, From the analysis, adult mortality is the only detectable reduction which acts as a negative feedback on the population, and is the only one needed to regulate the population in a way similar to the observed population trends. From a frequency distribution of ages at death, an approximate composite life table is constructed. This shows that males and females have similar age‐specific mortalities until old age, but then males survive relatively better. Information on the causes of mortality indicate that the regulating adult mortality is caused in part by undernutrition, which in turn is due to food limitation rather than to social and physiological factors. Predation causes only a small part of the annual adult mortality, and its effect is swamped by other factors. Diseases play an important part as a primary factor in juvenile mortality but not in adult mortality because of the development of immunity. However, both disease and predation are important as secondary agents killing adults already weakened by moderate undernutrition. It is suggested that they play an essential role by hastening the population's response to changes in the food supply, and hence dampening oscillations that might develop in population and resou

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00112.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryOver the past 70 years, human activity has severely limited the diversity and movements of large mammals in the region of Lake Nakuru National Park, Kenya. Game counts were begun in April 1970 to assess the status of those species remaining. The density of large mammals per km2was found to be 64.20±8.86 (mean ±S.D.) and the biomass density of the six major species in kg/km2was 6298±801. The biomass was most heavily concentrated in the grassland‐woodland area south of the lake. Defassa water‐buck was the dominant species accounting for 76% of the biomass density. The probable reasons for their dominance are: (1) favourable habitat; (2) decreased competition; (3) reduced predation; (4) control of poaching; and (5) non‐migratory habits. Future management may ultimately depend on the relationship of waterbuck to the food resources a

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00113.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryThe feeding habits of lions in Nairobi National Park have been observed between 1968 and 1972.Nairobi Park is briefly described and the herbivore and predator populations are discussed.The relationship between the changing status of the prey population for the period 1968‐72 and the feeding habits of the lions is examined and compared with data from earlier years.Selection ratio (preference ratio) for three of the most important prey species is more closely adjusted to the abundance of these species in the total ungulate population than was the case prior to 1968. Only warthog and eland form an exception. Predation on wildebeest shows the most marked decrease although this species has been increasing during the last 5 years.Wildebeest, kongoni, zebra and warthog have provided 80% of total kills throughout the study on the basis of numbers killed. On this basis, warthog has the highest preference rating. However, the largest contribution to the lions' diet expressed in kg is by kongoni, followed by zebra, wildebeest, eland and warthog, in that order.Kongoni and wildebeest contribute most during the first half of the year and zebra and eland during the last 6 months.Selection for males is significant in zebra and eland and highly significant in kongoni, whilst only in zebra is selection for juveniles eviden

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00114.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryAs part of a study of the ecology of a high density hippopotamus population (Hippopotamus amphibius) in the Luangwa river in eastern Zambia, a shot sample of 176 males and 161 females was examined. All animals were classified according to age (0–43 years). The female reproductive organs were removed, dissected, examined, and the lactational status was noted. Ovaries and corpora Iutea were weighed, sliced, and all follicles>5 mm in diameter were recorded. The testes of the males were dissected and weighed. Indications of puberty and maturity in the female were observed in some animals at an age of about 7 and 8 years respectively; but some animals were still not breeding until 20 years of age and the ages at which 50% of the female population reached puberty and maturity (Laws&Clough, 1966) were 11 and 13 years respectively. In the male, puberty begins at an average age of 6 years and maturity is reached at approximately 8 years of age. The data showed that lactation has no effect on ovarian weight or activity. The weight of the corpus luteum during pregnancy (36–72 ± 2–65 g) is significantly(P<0–01) greater than that observed in non‐pregnant animals (16–64 ± 2–46 g). Multiple ovulation occurs in 8–1

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1974.tb00115.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.tb00116.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.tb00117.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.tb00118.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.tb00119.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY