The feeding ecology of cape vultures Gyps coprotheres in a stock-farming area

Department of Zoology, University of the Witwatersrand, Johannesburg, South Africa; A.F. Boshoff; The Lakes Nature Conservation Station, Private Bag 6546, George, South Africa
Biological Conservation 01/1986; DOI: 10.1016/0006-3207(86)90027-3

ABSTRACT Cape vultures Gyps coprotheres in the southwestern Cape Province feed exclusively on sheep carcasses, within a limited foraging area. The size and shape of the foraging range was determined by means of a postal survey and confirmed by a radio-tracking study. The quantity of food available within the range, while seasonally variable, was estimated to exceed the colony's requirements. Data pertaining to daily feeding forays of individuals, monthly foraging patterns of the colony and the growth of nestlings indicated no seasonal shortages in the amount of food obtained. The colony remains susceptible to the effects of poisons used in the area; levels of contaminants recorded in most eggs are considered low.

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    ABSTRACT: Gas chromatography was used to establish the presence of quantifiable residues of 14 persistent chlorinated hydrocarbon pollutants in whole blood, clotted blood, heart, kidney, liver and muscle samples obtained from individual African whitebacked (Pseudogyps africanus), Cape griffon (Gyps coprotheres) and Lappetfaced (Torgos tracheliotos) vultures from different localities in South Africa. The levels of pesticides measured in whole blood samples of live specimens were compared between nestlings from two natural breeding colonies, adults from a wildlife area and birds held in captivity. Statistically significant (P<0.05) differences between populations were detected in geometric means calculated for gamma-BHC (lindane), alpha(cis)-chlordane and alpha-endosulfan. Five of the organochlorine contaminants displayed significant variations between concentrations detected in the clotted blood, organs and muscles excised from vulture carcasses. This includes residues of gamma-BHC, alpha-chlordane, dieldrin, beta-endosulfan and heptachlor epoxide. Values of the respective biocides measured in vulture samples were generally low in comparison to results documented for a number of avian species. Although no threat is posed by any of the organochloride pesticides, continual monitoring of especially breeding colonies is recommended. Furthermore, the suitability of African whitebacked vulture nestlings as basic bioindicators is highly advocated.
    Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 08/2001; 129(3):243-64. · 2.71 Impact Factor
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    ABSTRACT: Komen, J. & Brown, C.J. 1993. Food requirements and the timing of breeding of a Cape Vulture colony. Ostrich 64:86-92.Annual food requirements of a Cape Vulture Gyps coprotheres family, comprising one nestling and two adult birds, and a breeding colony were estimated. A family required 226,1 kg meat during a nestling period of 136 days, and 524,4 kg annually. The greatest family food requirements (average 1,98 kg/day) occurred between 60 and 100 days after hatching. The period between 60 and 100 days after hatching was the most critical period of food demands, because (a) this was the period of greatest nestling food requirements, (b) only one parent could be away from the nest at a time, and (c) daily family food intake was effectively constant due to temporal constraints on foraging. The estimated food requirements of a breeding colony comprising 152 breeding pairs and 98 nonbreeding birds was 89 388 kg meat annually, and 36 892 kg during the nestling period, with the highest food requirements (302 kg/day) occurring during September and October. In summer rainfall areas of South Africa, the highest numbers of wild ungulate and livestock mortalities occurred during September and October. It is suggested that, due to physical, physiological and environmental constraints on parent birds' ability to provide food, the breeding cycle of Cape Vultures is timed so that the period of greatest food consumption coincides with the period of greatest food availability.
    OSTRICH. 01/1993; 64(2):86-92.
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    ABSTRACT: Outdoor feeding trials were used to determine gross energy intake, energy assimilation efficiency and metabolizable energy intake of captive adult Cape Vultures (Gyps coprotheres). The mean ash-free dry energy density of daily pooled samples of feces and urine was 14.0 + 0.2 kJ/g. A consistently high mean energy assimilation effidency of 86.2 + 2.7% caused daily energy content of excreta to fluctuate according to the quantity of energy assimilated. Mean gross energy intake was 2926.8 + 349.1 kJ/day and mean metab- olizable energy intake was 2552.9 + 300.9 k J/day for birds with changes in body mass of 2% or less between start and end of feeding trials. The daily energy expenditure of a free-living adult, weighing 8.3 kg, was estimated to be 3006 kJ/day (DEE = 826.7 kJ/day x kg06').