Could wolves help songbirds weather climate change?

A new study has documented a decline in songbird populations in Arizona as a result of climate change.  What gets less attention in this story is that this decline is caused by elk over-browsing the plants that provide cover and nesting sites for the birds.  With warming temperatures leading to decreased snow pack over the last 22 years, elk have been staying at higher elevations for longer periods of time, leading to the intensive browsing and resulting reduction in songbirds.

We know that songbirds also declined in the Yellowstone area due to over-browsing of streamside habitat by elk. However, the reintroduction of wolves 15 years ago has facilitated the return of both the habitat and the songbirds, as well as a host of other species such as beavers and frogs. 

Given the role that wolves played in restoring the ecosystem in and around Yellowstone, one can’t help but wonder whether the beleaguered Mexican wolf population might be able to help mitigate the Arizona songbirds’ decline if only they were able to recover across the Southwestern landscape.  By keeping elk on the move, wolves would likely reduce the potential for over-browsing in any particular area.  This is supported by the researchers’ finding that in areas where elk were experimentally excluded and vegetation was allowed to recover, there were three times the numbers of songbirds than in areas that were browsed by elk. 

If Mexican wolves were able to reduce the browsing pressure in Arizona and enable the return of some of these songbirds, it wouldn’t be the first example of wolves helping to lessen the impact of climate change for other species.  Back in Yellowstone, researchers have found that wolves also provide a year-round supply of food for scavengers of all kinds, including ravens, eagles, coyotes, and bears.   In the absence of wolves, winter elk deaths were largely dependent on snow depth, and in years with less snow few elk would die—leading to a food shortage for many of the park’s animals.  With the reintroduction of wolves, however, there is now a steady supply of food throughout the winter – regardless of whether the season is mild or severe.   

The authors of that study credit the wolf – and predators in general – for buffering the ecosystem from climate change, stating: "We're finding that ecosystems that have lost a keystone predator may exhibit less resilience to the impact of climate change.”

The lessons we have learned from the return of wolves to Yellowstone show us what we are missing in the areas where top predators have been intensively removed.  Each new study adds to the already overwhelming amount of evidence that predators are a key part of our ecosystems and their presence is essential to maximizing adaptability to changing environmental conditions for all species. 

The Mexican wolf population has been struggling to recover in the wild after facing decades of political resistance, but a new recovery plan is currently in the works.  And the evidence suggests that if the wolves are allowed to succeed, we’ll ultimately be recovering much more than just the wolf.

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Photo credit: USFWS Mexican wolf