Climate change forces mammals to move north.

Byline: ANI

Washington, May 13 (ANI): A new study has shown that some mammal species in Michigan, US, are rapidly expanding their ranges northward, apparently in response to climate change.

In the process, these historically southern species are replacing their northern counterparts.

The finding was made by researchers at the University of Michigan, Michigan State University and Ohio's Miami University.

In the study, lead author Philip Myers, professor of ecology and evolutionary biology at U-M, and coworkers, analyzed distribution and abundance records of opossums and eight species of small forest rodents.

In addition to data collected by live-trapping animals over the past 30 years, the researchers relied heavily on specimens and notes in research museums including the U-M Museum of Zoology and the Michigan State University Museum.

"Museum collections have been underutilized in studying the effects of climate change," Myers said.

"We're fortunate in Michigan to have an amazing resource in the U-M Museum of Zoology collection, which contains great records of thousands of Michigan species from hundreds of locations, sampled over the past 100 years," he added.

Combining trapping data from Huron Mountain Club and other locations with museum material and road kill reports, the researchers ended up with a total of 50,000 records, 14,614 of which were for the nine mammal species in the study.

When those records were analyzed, they painted a clear picture of mammals on the move.

Of the nine mammal species examined, four have established strongholds or increased in abundance, while five have declined.

The increasing species-white-footed mice, southern flying squirrels, eastern chipmunks and common opossums-all are southern species, while the declining species-woodland deer mice, southern red-backed voles, northern flying squirrels, woodland jumping mice, and least chipmunks-are all northern species.

The south-to-north expansion pattern is what you'd expect if climate change is driving the advance.

To investigate, the researchers downloaded maximum and minimum daily temperatures from the National Climate Data Center for 16 weather stations in the Upper Peninsula, where changes in the small forest rodent community have been especially pronounced.

They then calculated monthly averages for minimum and maximum daily temperatures for each year between 1970 and 2007 for each station and for the region as a whole.

Across all 16 sites, average annual minimum daily temperatures increased significantly over the 37-year period.

Average annual maximum daily temperatures also rose, although not as dramatically.

The research team's results and conclusions dovetail with those of other groups that have found northward expansions of particular species in Wisconsin and Ontario and a shift from lower to higher elevations in the Yosemite National Park. (ANI)

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