No abstract

The Kafue lechwe population of Zambia numbers 90,000 and is divided by the River Kafue into two virtually segregated populations. The south bank population is known to be infected with tuberculosis but the north bank is thought to be free. One hundred and twenty-five south bank lechwe were cropped at random and lesions of tuberculosis were found in 45 (36 %). Isolates from lung lesions were typed as Mycobacterium tuberculosis vat. boris.Twenty-five of 27 pneumonia cases appeared active and on the assumption that these would die within 12 months the annual mortality due to tuberculosis was estimated as around 8,000.The disease in lechwe and the neighbouring cattle population is discussed.

Aerial surveys from 1970 onwards suggest a stable Kafue lechwe population of 94 000*9% on the Kafue Flats. The present distribution shows a contraction in dry and wet season range in comparison with 1953154.

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 8–10% of the animals.

SUMMARY Of at least 350 species so far recorded within the boundaries of the Niger Inundation Zone, no less than 108 (31%) are wholly or partially of Palaearctic origin. Five main habitats are recognized in the region: wetland, hygrophilous grassland, transition zone, non‐flooded areas and aerial. The habitats, the Palaearctic migrants and their possible Ethiopian competitors are described and discussed. The annual Niger flood regime enables Palaearctic waterbirds to find suitable habitats somewhere within the region during all seasons, but most widely during the autumn and winter months of the flood recession. Non‐aquatic species inhabiting flood plain grassland are scarce during the Palaearctic autumn, when the growth of vegetation reaches its maximum, becoming commoner and more diverse during the winter months. Wetland warblers of the genera Acrocephalus and Locustella have not been recorded on autumn passage. It is suggested that in some years at least, these and other trans‐Saharan migrants from the West Palaearctic overfly the Sahelian latitudes of mid‐West Africa. Species inhabiting the transition zone (which increases in area during years of below average rains and floods) are most in evidence at the end of the winter period and during the spring hot dry season, prior to northward trans‐Saharan migration. Habitats and species encountered in the non‐flooded areas are similar to those recorded in the Sahel zone elsewhere in West Africa. Aerial habitat is utilized by Common Swifts arriving en masse in early August, at the maximum development of the south‐westerly monsoon airstream. Several aquatic species and the first few trans‐Saharan migrants also occur during the summer rainy season. Some species (e. g. Whiskered Tern, Lesser Kestrel, Turtle Dove, Short‐toed Lark and Sand Martin) are most numerous during the late winter and spring hot seasons, when conditions provided by the Inundation Zone may be more suitable for pre‐migration feeding than in other parts of the Sahel zone. As yet there is virtually no information available to determine any effects that drought seasons or flood variation may have on the migrant populations.