Multiple habitats must be protected to save bumblebees

A new study from the British Ecological Society has found that targeted conservation measures are needed to protect bumblebees. Of the 24 bumblebee species found in the UK, one third are listed as species of conservation concern, threatened by loss and degradation of nesting and feeding habitat. 

For the investigation, the researchers used 10 years of data from the Bumblebee Conservation Trust’s BeeWalk scheme collected by citizen scientists. The study provides the most detailed overview of bumblebee habitat requirements across the UK.

The data from the BeeWalk scheme was combined with land cover data, climate date and detailed observer-collected habitat data. This allowed the researchers to look at associations between 14 UK bumblebee species and types of habitat.

A wide range of differences was found between the species and the types of habitat they are associated with. This suggests that a one-size-fits-all approach to conservation will not protect all species,  and that conservation efforts need to be carefully tailored.

The experts identified the kinds of habitat that could be used for conservation. Arable areas were found to be important for rare species like the large garden bumblebee (Bombus ruderatus), the largest species in the UK. Whereas large areas of semi-natural land, like moorland, were important for species such as the moss and the brown-banded carder bees (Bombus muscorum and Bombus humilis), and the bilberry bumblebee (Bombus monticola).

“Our results suggest that reversing the loss of semi-natural areas such as wetlands may be the single most generally effective action for bumblebee conservation, while improving habitats in urban and arable areas could benefit particular rare species. As one of the most nature-depleted countries in the world it’s really important that we better protect our native species and habitats in the UK,” said Dr. Penelope Whitehorn of the Karlsruhe Institute of Technology, who led the study.

“Our study highlights the value of citizen science for understanding bumblebees and their habitats. Citizen science also gives everyone a chance to contribute to protecting these species.”

The study also identified the different habitats of individual bumblebees. The queens and males were associated with areas of scrub, bracken and herbs – habitats that are good for nesting. By contrast, workers were more commonly associated with hedges and lanes, suggesting that these areas are valuable for providing food.

“Bumblebees need areas with lots of flowers available from March right through to September/October. Bees lose this vital resource when habitats are lost entirely because they’re either built on or changed into other environments or degraded through things like pesticide use,” explained Richard Comont.

As with many studies that rely on volunteers, the researchers did detect biases. Namely, a bias towards urban areas as volunteers selected sites to monitor bumblebees that were close to where they live. However, the scale of volunteer efforts still covered a wide range of landscapes, allowing for statistically robust findings.

“We’d like to find out why different species are associated with different habitats, so we can create and preserve the right conditions for them in the future,” said Dr. Whitehorn. “We also need to better understand how shifting climate and land uses might affect bumblebees and their habitats.”

This study is published in the Journal of Applied Ecology.

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By Katherine Bucko, Earth.com Staff Writer