Earth Protect Blog

Urban animals can’t take the heat

By Emily Anthes

The New York Times

For many wild animals urban environments are unappealing homes, covered in concrete and carved up by car traffic. As buildings go up and roads are laid down, some species seem to vanish from the landscape, and animal communities often become less diverse, scientists have found.

But not all cities are created equal. Urbanization appears to take a greater toll on wild mammals in hotter, less-vegetated locales than in cooler, greener ones, according to a new study, which was published in Nature Ecology & Evolution last week. The findings suggest that climate change could exacerbate the effects of urbanization on wild animals.

“As our climate warms, the heat of our cities is something that is going to continue to be a challenge to both us and wildlife,” said Jeffrey Haight, a postdoctoral scholar at Arizona State University and an author of the new study.

The researchers analyzed photos snapped by wildlife cameras at 725 sites across 20 North American cities. The cities, which included Chicago, Phoenix and Tacoma, Wash., were participants in the Urban Wildlife Information Network, an ongoing effort to collect data on urban biodiversity. In each city, the cameras were deployed in an assortment of locations; some camera sites, like those near airports or freeways, were highly urban, while others, like parks and trails, were less-developed.

The scientists studied the photos taken during the summer. They detected a total of 37 native mammal species, including raccoons, squirrels, rabbits, foxes, cougars and deer.

In general, the researchers found, wild mammals were more common and more diverse at less-urbanized sites, reinforcing findings from other studies. But wildlife seemed to cope better with urbanization in cities that were cool or lush than in those that were warmer or more barren.

For instance, as camera sites became more urban, mammal diversity dropped off more sharply in warm Los Angeles than it did in cooler Salt Lake City.