Gray wolves maintain the food chain in winter

Climate change has already had dramatic effects on individual species, with disruptions in range, reproductive success, and seasonal phenomena like migration. But, in a new study from the open-access online journal PLoS Biology (www.plosbiology.org), Christopher Wilmers and Wayne Getz show that the impact of climate change on many different species in Yellowstone Park can be buffered by a top predator - the reintroduced gray wolf (Canis lupus).

Gray wolves inhabited most of North America until US extirpation campaigns nearly eradicated them by the 1930s. In 1995, the US Fish and Wildlife Service reintroduced the persecuted predator into Yellowstone. Wilmers and Getz used data from the past 50 years to establish winter trends and model wolves' impact on the fate of resident scavengers faced with a changing climate. Their models show that wolf kills temper the potentially devastating effects of climate-related carrion shortages on scavengers. Unlike mountain lions and grizzly bears, wolves abandon their prey (usually elk or moose) once sated, leaving much-coveted leftovers for ravens, eagles, coyotes, bears, and other scavengers. Altogether, their modeling studies show that shorter winters without wolves will create intermittent food supplies that no longer track the needs of local scavengers. With or without wolves, late-winter carrion abundance will decline with shorter winters. But wolf kills buffer these shortages, providing meals that could determine whether scavengers will be able to survive and reproduce.

It seems clear that wolves have the potential to provide a safety net for scavengers, extending the time they need to adapt to a changing environment. Thanks to a rebounding wolf population, field researchers can measure the magnitude of this predicted buffer effect. The models described here can guide their efforts and help species adjust to major environmental shifts like climate change. Crucially, Wilmers and Getz's study shows that a robust food chain - including this still embattled top predator - may be even more important as ecological conditions deteriorate.

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Citation: Wilmers CC, Getz WM (2005) Gray wolves as climate change buffers in Yellowstone. PLoS Biol 3(4): e92.

Source : PLoS Biology