“Bumblebee species across Europe and North America are declining at continental scales, and our data suggest that climate change plays a leading, or perhaps the leading, role in this trend”.
“The net effect is that climate change is kind of like a vise, where [bumblebee populations] are being crushed from the southern edges of their range inward”, said Kerr, a professor of biology at the University of Ottawa in Canda.
When climate warms, many wildlife species expand into areas that used to be too cold for them.
There’s new evidence that wild bees, some of nature’s most industrious pollinators of wildflowers and crops, are getting squeezed by our planet’s changing climate. Live Science reports that climate change is advancing at a high speed and bumblebees are not able to keep the pace for adapting to the growing changes and demands on their way of life. Researchers have also argued that bees that have migrated to the north face more struggles as they lack the capacity to rapidly grow a new population when they move.
Normal Carreck, Science Director at global Bee Research Association, said the study helps them look in another direction.
In many cases, if an animal’s southern range moves up, so does its northern range, so that its entire geographic range shifts. These findings contradicted the earlier studies that pointed towards pesticide use, parasites, disease and loss of areas for habitat as some of the reasons for their decline. Bumblebees, however have “unusual evolutionary origins in the cool Palearctic”, the scientists write, which may help explain their rapid losses of terrain from the south and lagging expansion in the warming north. They examined more than 420,000 historical and current bumblebee observations from 1901 to 2010 across 67 different species. This is known as neonicotinoids and doesn’t mean they can’t harm the bees; only that they don’t affect the study’s results. Hotter climates seek to push bumblebees north, where there is less matter for them to pollinate.
“We need to have a thoughtful, worldwide discussion about whether we should be helping bumblebee species establish colonies in areas further north, called ‘assisted migration, ‘” the researcher Kerr said.
The new study shows that the culprit is not pesticides and it’s not simply land use changes-two other major threats to bumblebee populations and health.
Kerr’s study drew on museum records of bumblebees captured by naturalists and researchers over decades. And the shifting ranges could also be a problem for both wild plants and crops at the bees’ southernmost limits if the bumblebees aren’t around in the future to pollinate them, said Richardson.
