LAKE RUDOLF AND THE PALAEARCTIC EXODUS FROM EAST AFRICA

The 165 000 km² sub-desert corridor in which Lake Rudolf lies may affect the routes taken by Palaearctic migrants in eastern Africa. A five-week study was made at Lake Rudolf during the spring migration period. The area is important for water birds, especially waders. It is less important for land birds, although on passage several passerines occur abundantly on Central Island, and some commonly in similarly well vegetated area (Turkwel river, littoral reedbeds). Some may fatten there before emigrating. Evidently the sub-desert corridor is not so inhospitable that it is entirely avoided or overflown by migrants.     

THE WHITE-BREASTED CORMORANT IN SOUTH AFRICA

Akinsola, O.A., Ezealor, A.U. &; Polet, G. 2000. Conservation of waterbirds in the Hadejia-Nguru Wetlands, Nigeria: current efforts and problems. Ostrich 71 (1 &; 2): 118–121.

The ornithological importance of the Hadejia-Nguru wetlands at both national and international levels is well known. Current efforts at conserving the avifauna of the wetlands started with the establishment of the Hadejia-Nguru Wetlands Conservation Project (HNWCP) in 1987, as a joint international initiative to promote sustainable use of this hydric ecosystem in the otherwise semi-arid zone of north-eastern Nigeria. The present phase of the project started in 1995 with the major goal of maintaining the natural resources and function of the wetlands. This paper discusses recent activities of the project that have been directed towards conserving the wetlands, particularly its avifauna.

Bird monitoring and the annual dry season (northern winter) waterbird surveys remain the most publicised bird conservation effort of the HNWCP. However, recognition of the vital and central role of water in maintaining the ecological health of the wetlands has prompted the project to evolve a new strategy of regular meetings of the wetlands' water stakeholders (tagged “water-use advocacy”), to resolve periodic water-shortage and distribution problems.

Uncontrolled hunting of birds and habitat loss remain pressing problems throughout the wetland. The HNWCP has made efforts to curb these problems by sensitising the local communities through awareness campaigns and harnessing the efforts of concerned local and national organisations. However, the HNWCP has had difficult experiences regarding the problems of crop damage by avian pests from the wetlands.     

HETEROTROPHIC UTILIZATION OF ACETATE AND GLUCOSE IN SWARTVLEI,SOUTH AFRICA

SUMMARY

The utilization of dissolved organic compounds in Swartvlei was measured by the addition of single concentrations of ¹⁴C-labelled acetate and glucose to water samples, The results indicated acetate uptake was greatest in the aerobic zone while glucose was predominantly utilized in the anaerobic zone. With the exception of two months, integral glucose uptake was usually greater than the uptake of acetate. In August and September 1971 acetate was indicated as being utilized predominantly by flagellates and in December 1971 by dinoflagellates. During the remainder of the study, bacteria were assumed to be responsible for the uptake of acetate. The extensive weed beds which surround the upper reaches of Swartvlei may be a major source of acetate and glucose in the pelagic water column.     

BODY MEASUREMENTS,PLUMAGE AND MOULT OF THE SACRED IBIS IN SOUTH AFRICA

Lowe, K. W., Clark, A. & Clark, R. A. 1985. Body measurements, plumage and moult of the Sacred Ibis in South Africa. Ostrich 56: 111–116.

Body measurements, plumage and moult of Sacred Ibis Threskiomas aethiopicus were studied at Pretoria from July 1973 to June 1974. Adult and immature Sacred Ibises are sexually dimorphic in size. Bill length alone can be used to sex most birds. Body mass, wing, tarsus and tail lengths overlap greatly between the sexes but males are generally larger than females. The sexes show similar patterns of variation in body mass and gonad size throughout the year. Juveniles follow a different pattern of variation in these parameters. The plumages of adults, immatures and juveniles are described and compared. There is no sexual dimorphism in plumage pattersn. Moult in adults occurs mainly in the post-breeding period from January to August, and in juveniles and immatures throughout the year. Adult Sacred Ibises have an-extensive, irregular and asymmetrical moult. Factors affecting sexual size dimorphism in African and Australian populations are discussed.