More proof it ain't happening?
Study: Michigan mammals migrating north
TRAVERSE CITY, Mich. (AP) — Commonplace rodents such as opossums and white-footed mice are migrating rapidly northward in Michigan, suggesting climate change is taking hold in the upper Great Lakes region, says a newly released scientific report.
The growing abundance of rodent types that historically lived farther south, coupled with a decline of others long found north of the 45th parallel, has accelerated rapidly since the 1970s, say researchers led by biologist Philip Myers, of the University of Michigan.
The findings are similar to those of other studies that have linked northward animal migrations with warming temperatures in North America, Myers said.
The study, published in the June issue of the journal Global Change Biology, considered and dismissed other possible explanations for the evolving mammal populations, such as logging and urban sprawl.
Although based on data gathered only in Michigan's northern Lower Peninsula and Upper Peninsula, its findings carry implications for the entire upper Great Lakes and other northerly regions, Myers said.
Michigan's northlands are a good location for measuring the effects of climate on mammals, he said. They represent either the southernmost or northernmost extent of many species' range.
And the project was boosted by a treasure trove of records on mammal distribution in the area, including more than a century of field notes and specimen collections housed in research museums at the University of Michigan and Michigan State University.
Beginning in 1978, university researchers bolstered older records by live-trapping small mammals for study. Especially helpful were findings from a 6,400-acre virgin tract within the Huron Mountain Club, a private hunting and fishing enclave that was spared during a series of logging booms that started in the late 1800s.
Altogether, the researchers compiled more than 14,600 records dealing with nine mammal species chosen for study.
Of those, four are on the upswing in northern Michigan: the white-footed mouse, southern flying squirrel, eastern chipmunk and opossum. They historically lived farther south and have migrated northward. The opossum was found only in southern Michigan a century ago but now is common statewide.
Meanwhile, the five species in decline are longtime natives of northern Michigan: woodland deer mice, southern red-backed voles, northern flying squirrels, woodland jumping mice and least chipmunks.
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