摘要:

SummaryThe amount of food consumed by a clan of spotted hyaenas in the Namib desert was determined gravimetrically for 19 nights and the amount consumed by each individual was calculated according to its feeding time budget. At large, fleshy ungulate carcasses, each adult clan member ate about 8.7kg nightly, except for the bottom‐ranking male, who obtained only half that amount per night. Skin and bone remains were consumed at a slower rate of 2kg/hyaena/night. Medium‐sized ungulates were devoured rapidly so that each hyaena obtained more during such feeding nights than at large carcasses. Over a 29 day period, a hyaena clan consumed five cacasses at a rate of 4.0kg/hyaena/day, which compared well with previous estimates of average daily consumption in large social carnivores studied elsewhere. Annually, sixteen Namib hyaenas ate some 4.8% of the ungulate bio‐mass, removing, in terms of numbers 14.3% of the gemsbok and 2.2% of the mountain zebra. This depletion did not appear to limit these popula

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00977.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryMonthly changes in abundance of Thomson's gazelles at 142 locations on the Serengeti Plains are presented over a 3½ year period. Numbers of gazelles on the eastern plains were strongly correlated with rainfall, whereas numbers in the central and western plains appeared to be related to other variables. Movements of female cheetahs and non‐resident male cheetahs corresponded closely to the movements of Thomson's gazelles but those of resident male cheetahs remained relatively independent of the gazelle migrati

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00978.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryBetween April 1981 and December 1984 aerial surveys were conducted in the northern Central Kalahari Game Reserve, the Lake Xau area and a larger area in southwestern Botswana. Range conditions were monitored in the northern Central Kalah, ri Game Reserve. The migration of wildebeest to surface water at Lake Xau was documented. Since the Kalahari wildebeest population has had severely restricted access to surface water for decades and this access is steadily diminishing, it is inferred that the existing population is smaller than it used to be and can be expected to decline further in the future.

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00979.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryA sample of 535 small mammals, caught over a range of altitudes from 1500 to 4000 m in the Bale Mountains, on various expeditions from December 1971 to August 1986, enables the altitudinal zonation of the species to be delimited. The most abundant species,Lophuromys flavopunctatus, ranged from near the lower tree line at 1550 m, right up through the forested zones and onto the Afro‐alpine moorland at 3900 m. The endemicPraomys albipesalso ranged through the forest from 1550 to 3200 m, but was replaced in open habitats between 2400 and 3900 m byStenocephalemys griseicaudaand between 3000 and 4000 m byS. albocaudata, which was relatively more abundant than its congener at higher altitudes. Other moorland species, includingCrocidura fumosa, Otomys typus, Lophuromys melanonyxandArvicanthis blickiwere also commonest at 3800–4000 m, but, like theStenocephalemysspp., penetrated to lower altitudes in open habitats.Mus mahometwas confined to lower altitudes (1510–3000 m) and open habitats, apparently replaced byMus triton, not previously recorded from Ethiopia, in forested habitats at middle altitudes (1950–

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00980.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryMacrophyte succession in Jebba Lake, Nigeria, was observed through the first four years after impoundment. Two distinct serai phases, a floating fern phase and a draw‐down flora phase could be recognized.The floristic composition of the macrophyte vegetation was also investigated to check earlier predictions (Obot&Mbagwu, 1986) on the probable structure of the macrophyte flora. The failure of obligate floating macrophytes such asPistia, AzollaandSalviniato establish in the lake as predicted is discussed. However, rooted emergent macrophytes were observed to be more successful than would be expected from the prediction

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00981.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryFollowing the recent decline in browsing and grazing pressures and changed fire regimes in Queen Elizabeth National Park, Uganda,Acaciathickets have encroached on grassland habitats important for grazing mammals. The objective of this research was to test experimentally the effects of fire behaviour, using simulated and natural fuel loading conditions, onA. sieberianaseedling and sapling regeneration.A high fire intensity (3200 kW m‐1) in natural fuels stimulated high seedling emergence (172 seedlings m‐2) compared to 6 seedlings m‐2without fire. Also a highly significant linear regression was established between percentage top‐kill of seedlings and fire intensities. High fire intensities during late dry season fires were more effective in controlling sapling height growth than early dry season fires of low intensities. A conceptual diagram was developed to show the major factors and possible pathways leading to successful invasion byA. sieberianainto grassland openings of the

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00982.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryNestling African fish eaglesHaliaeetus vocifer(Daudin, 1858) in Queen Elizabeth National Park (QEP), Uganda, attained and exceeded the adult body weights of their respective sexes by fledging time. The growth curves conformed with the sigmoid form of most animal species. The overall growth rate,K(g/day), was low, averaging 0.077 ± 0.017 g/day and the timet10–90required to complete growth from 10 to 90% of the asymptotic weight wasc. 42 days. Brood size and hatching order did not significantly influence growth rates but the sex of the young did. The tarsus, femur and humerus reached adult sizes by fledging time but the standard wing did n

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00983.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryThe theoretical maximum rate of increase for the African elephant is calculated at 7%. This figure agrees closely with the rate of increase observed at Addo Elephant Park, the highest rate of increase reported for elephants living under natural conditions. An elephant population increasing at the maximum rate soon reaches a stable age distribution in which 48% of the animals are older than 11 years of age, (the age of first reproduction) and 6.7% are calves (less than one year old). Several papers have reported frequencies of calves in natural populations of up to twice this percentage. Calculations are presented to show that such high calf frequencies are both theoretically impossible on a sustained basis, and internally inconsistent with the population data presented in these papers.

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00984.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

SummaryThe only feeding habitats available to African lily trotters,Actophilornis africanus(Gmelin), at Lake Naivasha are mats of the alien water fern,Salvinia molestaMitch. This has replaced the native floating leaved water lily beds. Lily trotters were able to use these mats, taking invertebrate food items from the surface or turning plants over and pecking at the rootlets. Pecking rates and turning rates responded to the nature of the available food, with pecking rates high and turning rates low when terrestrial arthropods were found on the mat surface. Both pecking rates and turning rates were low when large aquatic food items, such as the swamp worm (Alma emeniMichaelsen), were available. Pecking rates and turning rates were both high when the predominant food items were aquatic insect larvae. The largest of these (hydrophilid larvae) were taken in preference to the smaller but commoner chironomid larvae. Colonization of the mats of S.molestaby invertebrates was low if the mats were affected by wind action but higher if they were constrained by enclosure or stranding; mats with higher invertebrate densities supported more feeding lily trotters.

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00985.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0141-6707    

DOI:10.1111/j.1365-2028.1988.tb00986.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY