SARC Assesses Three Bumble Bee Species

Date: 
Monday, April 15, 2019

The Northwest Territories (NWT) Species at Risk Committee (SARC) met April 2-3, 2019 in Fort Simpson and has released the results of the 2019 assessments on the status of yellow-banded bumble bee, western bumble bee, and gypsy cyckoo bumble bee in the NWT.

SARC determined that yellow-banded bumble bee is Not at Risk in the NWT. This species has been collected in the south-central and southwest NWT and is most likely present across a larger area. Increased sampling is providing more information, demonstrating that the species is still present in regions where it historically occurred. The yellow-banded bumble bee is noted to be in serious decline in areas of southern and central Canada, but appears to be relatively stable in the northwestern parts of its range, including the NWT.

SARC determined that western bumble bee is Data Deficient in the NWT. Only 5 specimens have been collected from the NWT, in 2011 and 2018. SARC was therefore unable to assess population size, population trends, or changes in range use over time. Although western bumble bee has been collected from only five sites in the NWT, it could conceivably be present throughout much of the southwestern NWT.

SARC determined that gypsy cuckoo bumble bee is Data Deficient in the NWT. The gypsy cuckoo bumble bee has been collected sporadically in the NWT since the 1940s; however, a major portion of its range has not been surveyed recently. This species is often hard to detect in surveys because it does not have a worker bee class, which is the class of bee that is most often seen foraging in great numbers in other species. Gypsy cuckoo bumble bees lay eggs in the nests of other bumble bee species instead of building their own nests, but then stay to help look after the host bee colony. Only one host species of bumble bee has been confirmed in the NWT (yellow-banded bumble bee, which has been assessed as Not at Risk); others are likely but unconfirmed (western bumble bee and cryptic bumble bee).

SARC was surprised with the amount of information available about bumble bees in the NWT, but there were a number of key information gaps, such as data on population size and trends, changes in species range and distribution, and threats.

Additional surveys, especially community-based monitoring and citizen science initiatives, should be undertaken to increase knowledge of these species and all pollinators in the NWT. Importing bees for honey production or pollination is becoming increasingly popular in the NWT. Imported bees can carry disease and compete with wild bees. Education around best practices for importing bees and beekeeping is needed, especially with respect to responsible management of hives and minimizing the spread of disease to wild bees.

Climate change may be the most important threat for these species in the future, but there are significant information gaps with respect to how they may be impacted by climate change. SARC recommends tracking changes in seasonal timing of flowering plants and spring emergence of bumble bees; if there are no flowers available to the bees in the spring, the effects could be devastating.

Details of these 2019 assessments and more information on these three bumble bee species can be found on the NWT species at risk website: www.nwtspeciesatrisk.ca.

SARC, established by the Species at Risk (NWT) Act, is an independent committee of experts responsible for assessing the biological status of species at risk in the NWT.