Although widespread across Alaska, Canada and the continental United States, the Canada lynx has declined dramatically in the U.S. in recent decades. In 2000, the species was listed as threatened under the U.S. Endangered Species Act.
The new research, published in the Wildlife Society Bulletin, suggests that the decline in the lynx’s prey could be caused by an explosion in the coyote population, which has increased due to the large-scale loss of wolves.
‘Trophic cascade’ of impacts
As top predators, wolves play a vital role in ecosystems by regulating the populations of their prey, such as elk and deer. They also keep a check on smaller predators, including the coyote.
“Before they were largely extirpated, wolves used to kill coyotes and also disrupt their behavior through what we call the ‘ecology of fear,’” said William Ripple, one of the researchers. “Coyotes have a flexible, wide-ranging diet, but they really prefer rabbits and hares, and they may also be killing lynx directly.”
Wolves are known to harass and kill coyotes, and coyotes are also less likely to venture into areas where wolves are present. The loss of wolves therefore allowed the coyote population in the United States to expand, with a consequent reduction in snowshoe hares and a knock-on impact on the lynx – an effect that scientists call a “trophic cascade” of impacts.
Wolves and the recovery of ecosystems
The researchers suggest that one way to help the lynx would be to support the recovery and reintroduction of wolves, which would keep coyotes in check and also control grazing ungulates such as deer, so helping plant communities to recover and hares to increase.
Although top predators such as wolves are still unpopular with some people, numerous studies have shown them to be vital to the health of ecosystems. For example, the reintroduction of wolves to Yellowstone National Park reduced the over-browsing of plants and trees by elk, allowing trees to re-grow along rivers. This allowed a range of other wildlife to flourish, including beavers, whose dams in turn created new habitat for fish. A range of scavenger species also benefitted from wolf-kills.
Coyote populations in Yellowstone halved after wolves were reintroduced, and this may be helping snowshoe hares to recover.
Although most of the focus of wolf restoration has been on the wolf’s value to the broader recovery of ecosystems, this new research shows that they can also play an important role in helping to save other threatened species.
Liz Shaw, ARKive Species Text Author