Rapidly decreasing population of wild bees is yet another disastrous side-effect of our planet’s changing climate, leaving us without one of the most important pollinators of crops and wildflowers.

Reports covering the bee populations across North America and Europe have been going on for the past century. Jeremy Kerr, a biologist from the University of Ottawa, decided to narrow his bee observations to bumblebees, which are easily identified by their big, fuzzy shape.

Unlike the honeybees managed by beekeepers, bumblebees roam freely across North America in dozens of different species. In total, bee observations have exceeded 422,000, and Kerr explained that each one of them is carefully registered so researchers know what type of bumblebee was observed and the time and location of the bee colony.

Kerr’s focus was a cross-reference between where each species was found several years back and where they are now. His collaborators helped him identify potential effects of a warming climate, as it was shown when some species of these wild bees were nowhere to be found in the warmest places where they used to buzz.

Published in the journal Science, Kerr’s report clearly reveals that the decrease in bumblebee population is not the results of pesticide use or land clearing. Ecologist Lawrence Harder of the University of Calgary has been studying and observing bumblebees for the past 35 years.

Even though she was not involved in this particular study, she complete agrees with its conclusions, explaining that the shape of a furry bumblebee allows it to keep its warmth in colder environments. However, the same characteristic makes it difficult for them to survive in heat.

One of the most surprising things that Kerr and his colleagues noticed is that bumblebees are rather different from other insects in the aspect of expanding their range at the cooler edge. Butterflies and insects in general move along to cooler regions when heat comes, but not bumblebees.

Kerr explained their observations showed they seemed kind of stuck, and Harder thinks he might know why. Unlike other insects, many bumblebee species are restricted by boundaries of vegetation, and not by cold temperatures criteria. Even if it gets really warm, bumblebees will stick to their favored open grassland instead of moving northward into Canada’s forests.

Honeybees get all the attention nowadays, as their numbers are threatened as well. But bumblebees play a crucial role in various ecosystems, as agricultural crops and wildflowers depend on them for the complex task of pollination.
Image Source: Beneficial Bugs