Bumblebees in danger as climate change shrinks their habitats

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One of the most important pollinators across the globe – bumblebees – are at the receiving end of human-activity-caused climate change as their habitats are shrinking, new research has revealed.

According to a research by scientists at the Universities of Calgary and Ottawa, published in Journal Science, climate change is having a significant impact on bumblebee populations across North America and Europe and the consequences could be troubling.

Researchers explain that unlike other species which adapt to climate change to a certain extent and expand their habitats, bumblebees haven’t been able to expand northwards and because of changing climate conditions, bumblebees are losing vital habitat in the southern regions of North America and Europe.

Paul Galpern, Assistant Professor of Landscape Ecology in the Faculty of Environmental Design, University of Calgary, co-author of study explains that even though climate change may be making making things too hot for them down south, they are not moving north as expected.

[Related: Bumble bees, other wild native pollinators more important for crops: Study]

For many wildlife species, when climate warms, they expand into areas that used to be too cold for them, pushing into areas that are closer to the North Pole in response. Bumblebee species are experiencing a different fate and being held at the northern most range while losing ground rapidly in the south.

Likening their current habitat as a vice, Jeremy Kerr, Professor and University Research Chair in Macroecology and Conservation, University of Ottawa and lead researcher of the study, explains that as the climate warms, bumblebee species are being crushed as the ‘climate vice’ compresses their geographical ranges.

This is causing widespread and rapid decline in population of these pollinators across continents, effects of which will be realised by humans and other species in terms of shortage in food supply. It is this revelation that is the most concerning because a very important piece of the ecological puzzle is under threat.

“Bumblebee species play critical roles as wild pollinators, not just for crops but of all sorts of plants,” says Galpern. “They provide an important service to ecosystems. They help plants produce fruits, seeds and this in turn provides both food and habitat for other animals, and so on.”

With nearly half a million observations compiled from museum collections and citizen scientist collectors from North America and Europe over the last century, this rich historical record enabled researchers to track thirty one bumblebee species in North America and thirty-six in Europe.

[Related: Strong ‘reserve squad’ of pollinating bees will help prevent potential food shortage]

“We don’t know for sure what is causing a stagnation at the northern end of things. Bees should be able to start new colonies in places they did not historically occupy. But we don’t know why this is happening so slowly that it looks like the ranges are not moving at all,” says Galpern. “This all points to the fact that bumble bees are at risk, and the services that they provide are increasingly threatened by human-caused climate change.”

Laurence Packer, an expert on bees and a co-author on the study with lead author Jeremy Kerr of the University of Ottawa, says that they didn’t expect large decline in population due to climate change. “The fact that at the northern edges of their ranges they are not moving north as the climate changes is actually really quite worrying,” he adds.

York University Environmental Studies Prof. Sheila Colla and co-author of the study added that as far a North American species are concerned, about a third of them are in decline and in some cases this has been quite dramatically, more than 90 per cent. Colla added that some species that were seen in huge numbers some 50 years ago are barely seen now, even within their normal range.