Global warming is shrinking where bumblebees range, research finds – ‘Bumblebee species across Europe and North America are declining at continental scales’Posted by Jim at Sunday, July 12, 2015
By Nicholas St. Fleur
9 July 2015
(The New York Times) – Climate change has narrowed the range where bumblebees are found in North America and Europe in recent decades, according to a study published Thursday.
The paper, published in the journal Science, suggests that warming temperatures have caused bumblebee populations to retreat from the southern limits of their travels by as much as 190 miles since the 1970s.
Logic would suggest that the northern reaches of their home turf would shift to higher latitudes by a corresponding distance. But that has not happened, leading researchers to think that the more northern habitats may be less hospitable to them.
“Bumblebee species across Europe and North America are declining at continental scales,” Jeremy T. Kerr a conservation biologist at the University of Ottawa in Canada who was the lead author of the report, said at a news conference. “And our data suggest that climate change plays a leading, or perhaps the leading, role in this trend.” […]
They compared population changes from 1974 to 2010, when temperatures began to warm, with changes from 1901 to 1974, when human-caused climate change was less of a factor. They found that the southernmost range of bumblebees retreated north at a rate of about 3 miles per year (the precise latitude was different for the many species of bees they studied).
For example, Bombus affinis once buzzed as far south as Georgia, but now is only rarely seen in states like Illinois, Maine and Wisconsin, while Bombus terricola, which thrived in North Carolina and the Mid-Atlantic, is now mostly seen in parts of Maine, New Hampshire, Ontario and Quebec, according to Leif Richardson, an ecologist from the University of Vermont and a co-author of the paper.
“One of the most striking results was that trends were often indistinguishable between Europe and North America,” said Paul Galpern, a landscape ecologist from the University of Calgary and a co-author of the paper. “Bumblebee species are responding quite similarly across continents since climate change began to really accelerate from 1975.” [more]
ABSTRACT: For many species, geographical ranges are expanding toward the poles in response to climate change, while remaining stable along range edges nearest the equator. Using long-term observations across Europe and North America over 110 years, we tested for climate change–related range shifts in bumblebee species across the full extents of their latitudinal and thermal limits and movements along elevation gradients. We found cross-continentally consistent trends in failures to track warming through time at species’ northern range limits, range losses from southern range limits, and shifts to higher elevations among southern species. These effects are independent of changing land uses or pesticide applications and underscore the need to test for climate impacts at both leading and trailing latitudinal and thermal limits for species.