Feeding ecology and diet

Carnivores do not eat only meat. In fact they have a varied diet and comparatively few are exclusively meat eaters. Some, such as the bamboo specialist giant panda (Ailuropoda

An Arctic fox (Alopex lagopus) crosses the ice. (Photo by J-L Klein & M-L Hubert/Okapia/Photo Researchers, Inc. Reproduced by permis-

Bat-eared foxes (Otocyon megalotis) play fighting in Kalahari Gemsbok National Park, South Africa. (Photo by Nigel J. Dennis/Photo Researchers, Inc. Reproduced by permission.)

An Arctic fox (Alopex lagopus) crosses the ice. (Photo by J-L Klein & M-L Hubert/Okapia/Photo Researchers, Inc. Reproduced by permis-

the frugiverous palm civets, kinkajou (Potos flavus), and raccoons, hardly ever eat meat. Mustelids are probably the most exclusively meat eating family, weasels and their allies being known as fierce and combative predators capable of killing prey up to 10 times their body weight and otters living mainly of fish, crayfish, crabs, and frogs. However, European badgers rely mainly on earthworms. Mongooses live mainly off insects, although some species are known as snake killers. Cats too are mainly carnivorous, the large cats are probably the most spectacular of all predators. Bears, viverrids, dogs, and hyenas are more omnivorous, although all, except viverrids, have meat-eating specialists amongst their ranks. Polar bears, African wild dogs, and spotted hyenas rarely divert from a meat diet, but brown bears, brown hyenas, and jackals are all truly omnivorous. The aardwolf is another strict specialist feeding almost exclusively on snouted harvester termites of the genus Trinervitermes. The marine carnivores feed on a variety of marine animals including fish, mollusks, crustaceans, penguins and, particularly in the case of the leopard seal, other seals. The world's most abundant mammal after humans, the crab-eater seal (Lobodon carcinoph-agus), feeds mainly on krill, and one of the giants, the walrus (Odobenus rosmarus), mainly eats mollusks.

A characteristic of most of the food eaten by carnivores is that it is of high quality, but difficult to obtain, therefore, they have to make full use of their opportunities. Many carnivores live under what has been called a feast or famine regimen. They are able to gorge themselves when the opportunity is presented, a spotted hyena can eat a third of its body weight in one sitting, and are also able to go for long periods without eating. Hibernating bears are the most extreme in this regard and are able to survive for half a year without eating,

A harbor seal (Phoca vitulina) rests at the water's edge. Seals are known to eat at least 67 species of fish, and more than 70 kinds of invertebrates, (Photo by E. & P. Bauer. Bruce Coleman, Inc. Reproduced by permission.)

drawing on fat reserves built up during the bountiful summer. If more food is found than an individual can consume, some species will cache the remains. Brown hyenas will scatter hoard ostrich eggs under bushes and in thick grass clumps should they find an unattended nest. Canids actually bury their excess food and show an uncanny ability for relocating it.

The impact that predators have on their prey is a complicated subject of great controversy and emotion as it often clashes with our own interests. Certain important principles need to be taken into account. Predators do not kill at will, or even the first prey they come across. They have to pit their skills and stamina against formidable opponents. The kill is the culmination of a range of behavioral strategies that may have taken hours or even days to succeed. The relationship between predator and prey is a delicate balance, an evolutionary arms race, where neither has managed to gain the upper hand. Ecologically speaking, predation is an important process that contributes to the dynamic nature of ecosystems. Predators help to keep prey numbers in check and often to dampen drastic fluctuations. They may weed out the less fit members of the prey population by selecting the old and infirm. They also often select males over females from the prey population, thereby lessening their impact as most prey species are polygamous; i.e. one male mates with several females. Furthermore, the impact they have on the prey populations is often mediated by environmental conditions such as droughts in Africa and severe winters in north America and Europe.

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