Bee Tongues Shorten as Result of Climate Change: Study

Tongues of bees living near the Rocky Mountains have gotten shorter over the last 40 years in response to climate change, according to a study co-authored by a University of Guelph professor.

The study, published in the journal Science, found bumblebees’ tongues shortened by 24 per cent between 1966 and 2014. Over the same period, the number of deep-flowered plants in the region has declined.

Shorter tongues may allow bees to obtain nectar more easily and from more kinds of flowers, said professor emeritus Peter Kevan, School of Environmental Sciences. He first studied these bumblebees while a professor at the University of Colorado in the 1970s.

“At the time, I was more focused on what flowers were being pollinated and what pollinators were doing the job than on tongue lengths of the native bees,” he said.

“The new team of researchers, headed by Professor Candace Galen, who was a student with me in the 1970s, got in touch with me and wanted my data sets from that time. They were the ones who decided to look at bees under the microscope and measure their tongues.”

The researchers found that some kinds of bees themselves were also smaller but not by enough to explain their shorter tongues.

“Bees have to be able to manipulate the longer flowers and reach in with their tongues in order to suck up the flowers’ nectar,” said Kevan. “Shorter flowers generally are easier for bees to feed at.”

The paper points to a 70-per-cent decline in flowers in alpine and arctic habitats around the world, caused by warming temperatures and drying soil. Bumblebees in those areas have had to adapt, said Kevan.

Referring to concerns about climate change even in the 1960s, he said “I worked in the Canadian High Arctic, and changes in glacial thicknesses and motions were being noticed even then.”

“In Colorado, we didn’t see the changes as much 40 years ago, but now we’re really starting to see the impact climate change is having on the available flowers. These same changes are affecting the alpine plants of our own Rocky Mountains and Coastal ranges.”

Climate change explains the change in bees’ tongue lengths in Colorado and the change in the composition of the flowering alpine meadows, said Kevan. He is now studying climate change impacts on pollination and insects in Churchill, Man.

“There isn’t something people can necessarily do to specifically fix the issue of bees, alpine flowering and bees’ tongue lengths. We should expect to see more of the pollination process disrupted.

“The scientific community is not expecting anything else but for climate change to accelerate. We just have to wait and see what happens and how the ecosystems change and adapt in the short and long term.”