I magine an elk or a moose standing still, without fear, as a pack of wolves or a grizzly bear moves in for the kill. It seems unlikely, but this is a common occurrence in areas where predators are reintroduced after several generations of absence. Prey animals tend to forget their fear over time and will often stand vulnerable to attack. This could threaten their survivability as a population if their numbers are already stressed. For this reason, wildlife biologists should carefully assess prey populations before introducing predators into an ecosystem, says John Gittleman, associate professor of biology , in an article published last week in the journal Science.
Wolves kill more prey when reintroduced into an ecosystem after several generations of absence.
Of 165 carnivore reintroductions worldwide, none assessed how prey populations respond to the reintroduction of predator species, he says. When carnivores are introduced by wildlife managers, the emphasis is almost always on the survivability of the predator rather than the prey. They don't know how to respond when a predator approaches because they've never experienced an attack. They often behave as if their evolutionarily developed fear has been completely lost. Prey animals in this situation, such as elk and moose, have been observed standing still allowing a newly introduced wolf population to simply walk up and make the kill, Gittleman says.