Cheetah menu: wildlife instead of cattle
Scientists from the German Leibniz Institute for Zoo and Wildlife Research (IZW) can give the all-clear: in a recent study they showed that cheetahs primarily prefer wildlife on their menu. The cheetah is a vulnerable species that only exists on Namibia’s commercial farmland in large populations. Here, local farmers see cheetahs as a potential threat for their cattle.
The conflict is an old one: wherever there are carnivorous wild animals, farmers are concerned about their livestock. In Namibia, the concern refers to the possible threat from cheetahs on cattle. When farmers in Namibia are missing a bovine calf, cheetahs are regularly under suspicion – nowhere else in the world are there as many animals of this vulnerable species as on commercial farmland in Namibia. But the suspicion can rarely be confirmed without demur.
In their recent study, scientists of the IZW investigated whether cattle is on top of the cheetahs’ menu. For this purpose they used an indirect method with which they were able to assess the diet over longer periods. “Traditionally, carnivore diet is determined by examining samples of fresh faeces. Faecal samples only provide a snapshot of the diet, based on the detected hair and bone samples of prey animals. One cannot therefore conclude which food items cheetahs devour in the long run”, explains Christian Voigt from the IZW.
Instead the scientists used samples of cheetah hair to determine the stable isotope ratios of carbon and nitrogen. Herbivores have different food webs. One is based on shrubs, trees and herbs whose photosynthesis contains intermediate products with three carbon atoms (C3). In contrast, grasses exhibit a C4 photosynthesis. These food webs can be differentiated with the help of the involved carbon isotopes. Herbivores typically only belong to one food web and the isotope ratio hence deposits in their body tissue. Small antelopes such as springbok or steenbok specialise on shrubs and herbs whereas the oryx antelope feeds on grass – just like the cattle. One step up in the food chain the isotope ratio of the prey transfers to its predator.
The study shows that herbivores of the C4 food chain, to which cattle belong, are nearly irrelevant to the cheetah’s diet. Grazers are only occasionally considered as prey by males when they occur in groups of two or three animals.
In this project the IZW scientists collaborated closely with the farmers. “We live with the farmers on their farmland and share our scientific results with them. In this way, we attain a very high acceptance”, emphasises Bettina Wachter. “The farmers passed on their experience in dealing with these big cats, as cheetahs cannot be simply lured with bait like many other carnivores”, she adds. This is owed to the fact that cheetahs only eat prey they brought down themselves. Thus, aided by the farmers, the scientists installed box traps at marking trees, which were hidden by thorn bushes except for a narrow passage. The only way to reach their tree is passing the trap. Once a cheetah is captured it is sedated and thoroughly examined: body length and weight are determined, samples of blood and hair are taken and then the scientists release the cheetah equipped with a tracking collar.
“We conclude that the farmer’s problems are smaller than they had assumed before this study”, Voigt sums up. This study, published in the scientific online journal PLOS ONE, will contribute to the protection of cheetahs – but not in adversity to the interest of the farmers. “We understand their position. The concepts of species conversation always need to be balanced against the livelihood of humans”, says Wachter. The study is therefore an important mile stone to resolve the conflict between farmers and cheetahs.
Publication:
Voigt CC, Thalwitzer S, Melzheimer J, Blanc A-S, Jago M, Wachter B: (2014): The conflict between cheetahs and humans on Namibian farmland elucidated by stable isotope diet analysis. PLOS ONE 9(8), e101917. doi:10.1371/journal.pone.0101917.
Contact
Christian C. Voigt
Tel.: +49 30 5168-517
Tel.: +49 30 5168-518
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Background information:
The Leibniz Institute for Zoo and Wildlife Research (IZW) investigates the vitality and adaptability of wildlife populations in mammalian and avian species of outstanding ecological interest that face anthropogenic challenges. It studies the adaptive value of traits in the life cycle of wildlife, wildlife diseases and clarifies the biological basis and development of methods for the protection of threatened species. Such knowledge is a precondition for a scientifically based approach to conservation and for the development of concepts for the ecologically sustainable use of natural resources. The IZW belongs to theForschungsverbund Berlin e.V. (www.fv-berlin.de)
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The Leibniz Association is made up of 89 independent research and scientific institutes, as well as two associated members. Their public and research functions are of national importance and comprise a major component of Germany’s publicly-funded research potential. Leibniz Institutes maintain more than 2,300 contracted cooperations with international partners in academia and industry, and some 2,200 foreign scientists contribute to Leibniz Institutes’ output on a temporary basis each year. Formal cooperative partnerships have been or are currently being developed with scientific institutions in France, Japan, Korea, Canada, Poland, Taiwan, and India. Third-party funds of about € 330 million per year indicate high competitiveness and excellence. Leibniz Institutes currently coordinate 75 projects funded by the European Union. They were also awarded grants by the European Union (with a value of € 42 million) and the German Research Foundation (DFG, € 55 million) in 2010, while € 51 million are a result of cooperations with industry partners. Leibniz Institutes contribute to clusters of excellence in fields such as mathematics, optical technologies, materials research, bio-medical research, environmental research, bio- and nanotechnology, as well as biodiversity, economic policy, and educational research. Altogether, ca. 17,200 people are employed at Leibniz Institutes, among them 8,200 researchers, including 3,300 junior scientists.