Bumblebee territory shrinking under climate change

Across North America and Europe, species that live in the South are dying off, whereas bumblebees that reside in the North are failing to migrate to cooler areas, according to a study published today in Science. Meanwhile, few species have expanded their northern territories. The pervasive collapse of honeybee colonies, in particular, has captured national attention. “Oddly, several other species of bumble bees here seem to be doing fine”.

“We can manage around this for a little while… but ultimately we have to fix this climate change problem”, he added.

The rates of loss are about nine kilometres a year from those southern areas and are consistent across both continents.

Exactly what can be done to help bumblebees is not clear.

A strong correlation was found between what was happening to the bees and climate change.

“For species that evolved under cool conditions, like bumblebees, global warming might be the kind of threat that causes many of them to disappear for good”.

“We’re playing with fire” by warming the climate, “and we are now going to be paying some of those consequences”, said Jeremy Kerr, an entomologist (insect science) at the U of O. Yet what was once a common site on the southern end of their range is becoming rare or nonexistent. But the researchers in this study found this was not the case for bumblebees.

While the bees are losing ground at the southern limits of their ranges and at lower elevations as temperatures rise, they are not compensating by shifting northward or expanding into new territories that were formerly too cold. “But these are areas that are adjacent to the places where these species are found normally”.

Declining populations have knock-on effects.

This geographic shift “could lead to problems for agriculture”, said Richardson.

“We all know the issues with climate change and the difficulties governments face in trying to tackle it”. Wildflowers and agricultural crops alike depend on them. This means that bumblebee populations are now highly compressed – leaving a void that other wild bee species probably won’t be able to fill.

As the climate changes, plants and animals are on the move. They also built statistical models to test whether any range shifts were best explained by climate change, or whether two other factors-changes in land cover and the use of pesticides such as neonicotinoids, which have been implicated in smaller-scale bee declines-also played a key role.

Kerr says butterflies evolved from the tropics and have complex biological mechanisms for coping with heat. Previous studies have tied extreme warming events to bee losses–a bad omen for the humans who rely on them to pollinate crops.

The scientists aren’t sure why bumblebees haven’t been able to expand their northern edges.

Climate change appears to be a major factor in the decline of some bee populations.

“If you imagine a vehicle that starts running out of coolant and starts blowing steam out of the front of the hood, that’s kind of like an analogy for what bumblebees do when it gets too hot”, Kerr said. The reason remains unclear. In the meantime, there are some actions humans can take to try to help out their struggling populations. But there are some other strategies conservationists can try in the meantime. “We think there’s an urgent need” to understand how plants in the abandoned areas along the bees’ southern margin are responding, he told InsideClimate News.

“Bumblebees are pretty mobile creatures”, he said in a statement.

The analysis indicates that warming is having a greater impact than pesticides or land use change. And citizens can even help out by diversifying the plants they grow in their own back yards to attract more pollinators, said Laurence Packer, another author on the study and a professor of biology at York University, at Wednesday’s press conference. Because they can occupy a niche as early and late season pollinators, farmers, forests and flowers could all suffer from their disappearance.

“The impacts are large and they are under way – they are not just something to worry about at some vague future time”.