When the topic of bees comes up most people will turn their thoughts to the well-known honey bee. However, there are many native species of wild bees to keep in mind. Wild bees, including bumble bees, are very critical pollinators within many plant networks. They are fantastic pollinators of crops and wildflowers, providing many of the foods we love, as well as maintaining habitats that support a wide variety of organisms. Unfortunately, bumble bee declines have been observed in southern Ontario, including declines of the widely known species-at-risk, the rusty patched bumble bee (Bombus affinis).

For my master’s research, I teamed up with Wildlife Preservation Canada’s Bumble Bee Recovery Program to help assess bumble bee populations in areas of southern Ontario, by replicating a former study conducted in the 70’s, and more recently in the early 2000’s. We are investigating the changes in abundance, diversity, and floral use of bumble bees in southern Ontario in comparison to previous records The former studies researched areas within Guelph and Belwood, Ontario and revealed declines in both abundance and diversity of certain bumble bee species in the region. Reassessing these areas is important to see if declines have continued and can give insight into what is causing declines, as well as overall trends in these bumble bee populations.

From April – October 2021 we have been sampling bumble bees once a week. Bumble bees are surveyed using a catch and release method, by walking 1km at each of the sites. Each individual is identified to species and caste (queen, worker, male) and recorded.

Yellow bumble bee (Bombus fervidus) queen. Photo: T. Kerekes

Two-spotted bumble bee (Bombus bimaculatus) queen. Photo: T. Kerekes

Another integral part of the project is to take note of the flowers that the bumble bees are interacting with. To do this, flower species on which bumble bees are found are recorded, and pollen from the bumble bee’s pollen basket (corbicula) is swabbed to be later identified. The flower density and richness of sites is also being sampled using a 1m2 square every 100m along the 1km walk. Conducting this floral assessment will help us investigate if certain floral densities or the presence of specific species correlates to more bumble bees being found in that area. Since flowers are critical in providing bumble bees with the pollen and nectar they need, it is essential that we understand which flowers they rely on or prefer to ensure they continue to have the proper resources in the future.

Taylor conducting a floral assessment along the transect using one square metre. Photo: T. Harrison

We have had some interesting preliminary findings on bumble bee diversity in the region. We found a total of 12 bumble bee species when combining data from both the Guelph and Belwood sites. When looking at each site respectively, there is slightly higher diversity at the Belwood site with 11 species being found there and 10 being found at the Guelph site. One interesting observation we noted was the sighting of the Vulnerable American bumble bee (Bombus pensylvanicus) which was found only at the Belwood site.

We look forward to further exploring the data we have collected and making comparisons to previous studies to better understand these amazing pollinators.

American bumble bee (Bombus pensylvanicus) on autumn olive. Photo: T. Kerekes

Taylor Kerekes

Master’s student, York University

Taylor is completing her MSc in Biology at York University. Her research focuses on the conservation and ecology of native bees in southern Ontario. By looking at their interactions with floral use and investigating possible reasons for declines, she hopes to gain a better understanding on what we need to do to help preserve native bee populations.