Moose living in areas without any natural predators are easy targets when bears and wolves are reintroduced, but they wise up quickly, says a US team.
Within one generation, the predation rate drops to the level found in areas where the animals have long co-existed. This has important implications for programmes to reintroduce predators, says Joel Berger of the University of Nevada.
Over 160 carnivore reintroduction programmes have been carried out worldwide, but none has assessed the response of prey populations, says John Gittleman of the University of Virginia. 鈥淏erger鈥檚 work suggests that reintroductions are not as worrisome as they might be, as long as the prey population can sustain the first wave of incoming predators without quickly going extinct,鈥� he says.
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Berger thinks much more work must be done. 鈥淲e need to improve our understanding of how prey species learn about predators. This issue is critical for conservation biologists, since so much of our planet is under assault from feral and introduced predators,鈥� he told 快猫短视频.
Scents and sounds
Berger鈥檚 team studied moose populations in Wyoming and Alaska in the US, Norway, Sweden and Denmark. The moose in the Scandinavian sites were being re-exposed to wolves and bears.
The sites in Wyoming included areas where there were no predators, as well as areas where the wolves and bears were being re-introduced. In Alaska, bears, wolves and moose have co-existed for about 9000 years.
The team already knew that moose exposed to new predator populations are more vulnerable. But they didn鈥檛 know how long it would take the moose to learn to fear them.
The team used scents and sounds associated with wolves and bears to test the moose鈥檚 responses. They found that the 鈥榥aive鈥� moose did not respond in the same way as experienced populations. But within one moose generation 鈥� 7.5 years 鈥� this had changed.
Female moose that lost calves became hyper-vigilant to wolf howls in particular. Berger thinks this behaviour then rubs off on calves, making their generation much less vulnerable to attack.
The possibility of 鈥榩riming鈥� inexperienced populations before new predators are introduced should be investigated, says Gittleman.
鈥淚n captivity, animals have been trained to be wary of predators by 鈥榗ontrolled harassment鈥�,鈥� he says. 鈥淟ive domestic dogs have been used, as have stuffed badgers, to prime ferrets. In the wild nothing like this has been attempted.鈥�
More at: Science (vol 291, p 1036)