Caribou, Deer, Elk & Moose - Sounds Wild
Caribou Swamp Predators


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Swamping predators

Spring on the north slope of the Brooks Range, and hundreds of thousands of caribou have congregated on their traditional calving grounds. The four largest caribou herds in Alaska have their calves north of the Brooks Range on the coastal plain. Tens of thousands of caribou calves are born in about a three week period at the end of May and the first weeks of June.

All those caribou calves attract predators - but they also overwhelm the predators. It's known as predator swamping, or predator saturation - an anti-predator adaptation where prey occurs for a short time at very high densities, which reduces the probability of an individual animal being eaten. When predators are flooded with food, they can only eat so much, and the prey animals prey benefit from safety in numbers.

Wolves and bears and to a lesser degree, wolverines and golden eagles, watch the herds and eat newborn calves. But this window of opportunity is short-lived; when caribou calves are just a few weeks old they are able to keep up with their mothers and other adults in the herd and keep away from wolves and bears. Because tens of thousands of caribou are all born within a very short time, predators are swamped with food.