Observations by Citizen Scientists Expand Known Range of the Two-Spotted Bumble Bee

How can researchers be in more than one place at a time? By mobilizing a network of volunteers with cameras! One of the powerful aspects of Bumble Bee Watch, a citizen science project that allows contributors to record bumble bee observations, is that participants submit records of bumble bees from across North America including in areas not often surveyed by researchers.

This fall, after researchers verified many of the bumble bee observations, particularly from Eastern Canada, they were excited to find records of the two-spotted bumble bee (Bombus bimaculatus). This species is recognizable by two spots of yellow hair (or alternatively a “w” or “chisel” shape) on the second band on the abdomen of a bee. Past range maps for this species included the central and eastern part of the United States and Ontario and the extreme south of Quebec. Now, a map of the records submitted to Bumble Bee Watch for the two-spotted bumble bee clearly show an expanded presence in Quebec, records in all three Canadian Maritime provinces, and a westward push into the prairies!

The green dots in the image above indicate the location of verified records in the Bumble Bee Watch database of the two-spotted bumble bee (Bombus bimaculatus) in North America, as of September 29, 2017. The shaded area represents the previously known range of the species.

It is not clear if this species has recently expanded its range into these provinces, or if it is the increase in survey efforts resulting in the new finds. Interestingly, the relative abundance of the two-spotted bumble bee ranges from 3–6% in the Maritimes, 8% in Quebec, 10% in Ontario, and 8–24% in the Prairies according to the data we have verified to date in Bumble Bee Watch. Regardless as to the reason for the bees now being found in new areas, it is an example of how by submitting photos you can have a direct impact on even our basic knowledge of bumble bees. Keep up the great work everyone!

One example of a new record of B. bimaculatus found in the Maritime region of Canada, outside of its previously known range. Photo by Dave Angelini via bumblebeewatch.org.

by Victoria MacPhail, York University

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