Despite the wide environmental tolerances of various cichlid species, they show relatively little morphological diversity. However, due to their phenotypic plasticity, confusion in species identification occurs. Therefore, fifteen cichlid species were analysed by comparing selected meristic and morphometric characteristics to determine the value thereof in identification keys. The results show that although it was possible to identify some species by means of discriminant function analysis, the value of the individual characteristics in routine identification is extremely low due to vast overlapping distributians. It can be concluded that other or additional characters should be incorporated in identification keys.
Reptiles and amphibians from the Etosha National Park were recorded in 1983, 1984 and in June 1985. Three species of frogs and 30 reptile taxa were documented, representing l I snakes, 17 lizards and 2 chclonians.
Culture and serological results obtained during a 5-week field study on anthrax in the Etosha National Park are presented. With one exception - a water sample from a natural fountain - Bacillus anthracis was only isolated from animal specimens or environmental samples associated with animals known to have or suspected of having died of anthrax and no environmental ""reservoir"" for the bacterium could be identified. In laboratory tests, vegetative forms of B. anthracis inoculated into water samples declined rapidly in number and spore forms showed no inclination to germinate.
The Cape vulture is a declining endemic in southern Africa and needs to be carefully monitored. In view of the spatio-temporal separation of the various age classes it is important to record the age af a bird with each sighting. This has not happened in the past as no clear, concise ageing guide was available. Detailed descriptionptions and photographs are presented of birds of each age class. This is done for seven nestling categories and five age classes of free-flying birds.
A supplementary feeding scheme was initiated at the Waterberg Plateau Park, South West Africa/Namibia, in an attempt to reverse the decline in the Cape vulture Gyps coprotheres population. Cape vultures were considered to successfully exproit the carcasses provided at the feeding station.
Spotted hyaena Crocula cracuta demography was studied in Etosha National Park, South West Africa/Namibia. In central and eastern Etosha, spotted hyaenas were most abundant in areas occupied by the migratory plains ungulates, eg. zebras Equus burchelli, springbok Antidorcas marsupiaIis, wildebeest Connochaetes taurinus. Hyaena density (5 adults and subadults/100 km2) estimated in a portion of the migratory plains ungulate range was low compared with densities reported from most other conservation areas.
Two exposed beaches on the central Namib coast were sampled quantitatively to determine intertidal macrofaunal community structure and zonation. The shallow subtidal rnacrofaunal community of the more protected beach was sampled using a diver-operated suction sampler. Both beaches support moderately rich communities showing affinities to regions both to the north and south. Zonation patterns of the macrofauna on both beaches are discussed and compared with other sites.
The occurrence of invasive alien plants in the Namib Naukluft Park in areas disturbed by the activities of man are listed. Datura innoxia, Nicotlana glauca, Prosopis spp. and Ricinus communis were the species which occurred most frequently. Most invasive plants were associated with an artificial supply of water. Datura innoxia was found primarily downstream of river fords suggesting that it has spread as a result of road building and maintenance activities. The intention of this report is to serve as a baseline for future monitoring of alien plants and to indicate which species, and which areas, require immediate management action to eradicate or prevent further spread of these plants.
Plant species diversity plant cover and plant density are reported for three dunes situated across a climatic gradient in the Namib Desert. Substrate penetrability, dune slope and dune aspect, parameters of importance to the plant community characteristics, are also reported. The central site, Bushman's Circle, had the greatest plant species diversity wlth four perennial species having more than 0.5% crown cover values. The eastern site, Far East, had two such species, while Nara Valley, the western site, had one.