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North America's mammals are seeking refuge from the heat in forest habitats

In a recent study led by UC Davis, researchers found that in North America’s hottest regions, mammals prefer forests over areas dominated by human activity. 

The research revealed that mammals, including pumas, wolves, bears, rabbits, deer, and opossums, are 50% more likely to inhabit forests than open habitats in hotter regions, while the opposite is true in colder areas. 

“Different populations of the same species respond differently to habitat based on where they are,” said study lead author Mahdieh Tourani. “Climate is mediating that difference.”

An example of this is the eastern cottontail rabbit, which prefers forests in hotter areas but tends to occupy human-dominated habitats in colder regions.

Biodiversity crisis

“Addressing the ongoing biodiversity crisis requires identifying the winners and losers of global change,” wrote the study authors. 

“Species are often categorized based on how they respond to habitat loss; for example, species restricted to natural environments, those that most often occur in anthropogenic habitats, and generalists that do well in both.”

“However, species might switch habitat affiliations across time and space: an organism may venture into human-modified areas in benign regions but retreat into thermally buffered forested habitats in areas with high temperatures.”

Focus of the study

For the investigation, the researchers used data from Snapshot USA’s extensive camera trap network.

“We analyzed 150,000 records of 29 mammal species using community occupancy models,” said Tourani. 

“These models allowed us to study how mammals respond to habitat types across their ranges while accounting for the fact that species may be in an area, but we did not record their presence because the species is rare or elusive.”

Ecological flexibility 

This research challenges the traditional conservation biology practice of categorizing species into simple groups based on their compatibility with human environments. 

The researchers say there is growing recognition of ecological flexibility, and that species are more complicated than those two categories suggest.

Habitat conservation 

“We can’t take a one-size-fits all approach to habitat conservation,” said study senior author Daniel Karp. “It turns out climate has a large role in how species respond to habitat loss.”

For example, if elk are managed under the assumption that they can only live in protected areas, there may be missed opportunities to conserve them in human-dominated landscapes.

“On the other hand, if we assume a species will always be able to live alongside us, then we might be wasting our effort trying to improve the conservation value of human-dominated landscapes in areas where it is simply too hot for the species,” said Karp.

Study implications 

The study highlights the growing importance of preserving forest cover for wildlife conservation in the context of a warming climate.

“If we’re trying to conserve species in working landscapes, it might behoove us to provide more shade for species,” said Karp. “We can maintain patches of native vegetation, scattered trees, and hedgerows that provide local refugia for wildlife, especially in places that are going to get warmer with climate change.”

The study is published in the journal Proceedings of the National Academy of Sciences.

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