Sex Differences in Giraffe Feeding Ecology: Energetic and Social Constraints

Ethology - Tập 87 Số 1-2 - Trang 79-89 - 1991
Truman P. Young1, Lynne A. Isbell1
1School for Field Studies, Beverly, and Animal Behaviour Group, Department of Anthropology, University of California, Davis

Tóm tắt

AbstractSex ratios of giraffe groups differ in different habitats, with open vegetation having female‐biased groups, and tall, thick vegetation having male‐biased groups. On a ranch in south‐central Kenya, we quantified habitat differences of male and female giraffe groups and showed that the preference for open habitats by female groups was limited to groups with young. We suggest that this difference is due to the avoidance of predators of young giraffes. We also showed that rates of giraffe feeding peaked at intermediate feeding heights equal to approximately 60% of adult giraffe height. In the dense habitats with a variety of tree heights used by male groups and female groups without young, both male and female giraffes fed most at heights where they could feed fastest. However, in the open habitats used by female groups with young, females fed mostly at heights below optimum because these habitats are dominated by short food plants. On the other hand, the dominant males accompanying these female groups fed at heights above optimum on rare tall trees, possibly to increase intrasexual vigilance. Apparently, both male and female giraffes sometimes forfeit feeding efficiency tor short‐term reproductive gains.

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Tài liệu tham khảo

10.1163/156853974X00534

Dagg A. I., 1976, The Giraffe: Its Biology, Behavior and Ecology

10.1111/j.1365-2028.1990.tb01136.x

10.1111/j.1365-2028.1966.tb00889.x

10.1111/j.1365-2028.1972.tb00855.x

Hall‐Martin A. J., 1974, Food selection by Transvaal lowveld giraffe as determined by analysis of stomach contents, J. S. Afr. Wildl. Manage. Assoc., 4, 191

Hanson R. M., 1985, Diets and trophic ranking of ungulates in the northern Serengeti, J. Wildl. Manage., 49, 823, 10.2307/3801717

10.2307/1033

10.1111/j.1096-3642.1958.tb00687.x

10.2307/3793

10.1111/j.1439-0310.1977.tb00074.x

10.1111/j.1365-2028.1979.tb00453.x

10.1111/j.1365-2028.1972.tb01173.x

10.1111/j.1365-2028.1978.tb00419.x

10.1111/j.1558-5646.1977.tb01019.x

Ngog‐Nje J., 1984, Regime alimentaire de la girafe au Parc National de Waza, Cameroun, Mammalia, 48, 173, 10.1515/mamm.1984.48.2.173

Owen‐Smith N., 1985, Ecology and Management of the World's Savannas, 345

10.1111/j.1365-2028.1983.tb00326.x

10.2307/2403043

10.1111/j.1469-7998.1984.tb04288.x

Pellew R. A., 1984, The Encyclopaedia of Mammals, 534

10.1016/S0003-3472(74)80049-7

10.1080/00222938200770381

10.1080/00222938500770471

Pulliam H. R., 1984, Behavioural Ecology

Pyke G. H., 1977, Optimal foraging behaviour: a selective review of theory and tests, Qu. Rev. Biol., 52, 371

10.2307/1936781

Wyatt J. R.1969:The feeding ecology of giraffe (Giraffa camelopardalisL.) in Nairobi National Park and the effect of browsing on their main food plants.MSc Diss. Univ. of East Africa Nairobi.

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Ethology

Tập 87 Số 1-2

79-89

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