Madoqua - Volume 16, Issue 1, January 1989

A survey or the Eastern Caprivi Strip, SWA/Namibia, during January to March 1986 resulted in the collection of 26 species of anurans, of which four are new records for the country. Ptychadena cotti, Ptychadena taenioscelis, Ptychadena upembae and Phrynobatrochus stewartae are known from north and east of the area, and demonstrate a link with the tropical frog fauna in Malawi. An annotated list of species collected from the Eastern Caprivi Strip is presented.

Several options for the inheritance of the red colour in the Mozambique tilapia, Oreochromis mommbicus are discussed. Breeding with only red mutants resulted in 100% red progeny, while crossing typically coloured individuals and red mutants provided silvery coloured offspring. Interbreeding this offspring resulted in a mixture of red, red typical and typical coloured individuals. It is obvious that the red colour is not due to albinism nor is it the result of a single recessive gene.

Thc summertime activity pattern of the tenebrionid beetle Physadesmia globosa was investigated using focal animal sampling. Beetles have a bimodal activity pattern with activity peaks during the morning and the late afternoon. The morning activity peak is divided into an early bout of foraging followed by sexual behaviour.

Veld surveys and game counts were conducted quarterly during 1982 and seasonally during 1983/84 on a typical pro-Namib plain on the eastern boundary of the Skeleton Coast Park. A strong correlation between veld condition and rainfall was evident. The aim of this study was to establish the relationship between fluctuations in veld conditions and the seasonal movements of large herbivores on a typical Namib plain along the eastern boundary of the Skeleton Coast Park.

The proposal that Aloe ramossisima be reduced to varietal rank under A. dichotoma, based on a low incidence of ramossisima-type branching pattern (less than 100 mm above ground level) in most A. dichotoma populations, is invalid, as the ramossisima-type branching pattern has a different cause in the two taxa. Branching patterns in A. dichotoma populations show a majority of first branchings at between 1.5 m and 2.4 m above ground.

A morphometric and biochemicaI genetic comparison of Barbus aeneus and B. kimberleyensis with B. cf. kimberleyensis from Hardap Dam, SWA/Namibia, revealed that the latter population showed distinct evidence of hybridization between B. aeneus and B. kimberleyensis. A similar comparison of the three Labeo-populations from Hardap Dam alsa indicated hybridization between L. capensis and L. umbratus.

Problems regarding the subspecific status of Tilopia rendalli (Boulenger 1896) and the lack of knowledge regarding the genetic status of these populations made it necessary to examine T. rendalli morphometrically and electrophoretically. Blood serum and muscle samples were respectively analysed on polyacrylamide and starch gels.

The range of X. princeps is confined to a narrow band along the whole inland escarpment of SWA/Namibia, extending northwards into southern Angola. X. princeps are diurnal and reduce their exposure to high ambient temperatures through special behaviour (e.g. using the tall as a parasol). They live singly or in family groups of up to three (four?) animals.

Marsh owls Asio capensis were found at 13 localities along the northwestern Namib, SWA/Narnibia. Three nests were found. These records indicate a more extensive distribution along the Namib coast than was previously rhought. Observations were made on the owl's hunting methods, food, breeding biology and behaviour near thc nest.

The major rivers of the Namib Naukluft Park were surveyd to determine the degree of infestation of alien invasive plants. The Swakop and Kuiseb Rivers had the densest infestations, the Tsondab and Tsauchab Rivers had less dense infestations, while no alien plants were found in the Awasib and Koichab Rivers. Datura innoxia and Nicotiana glauco were the most abundant alien plant species.

1447 km of 330 kV and 220 kV electricity transmission lines in South West Africa/Namibia were surveyed from a helicopter. Only one collision victim, a secretarybird Sagittarius serpenturius, was found, and there was no evidence of bird electrocution.