The western bumble bee (Bombus occidentalis) was historically very common throughout the western United States and Canada. However, in the last 20 years it has declined by more than 90% according to a recent study (Graves et al. 2020). It is suspected that this species is very vulnerable to disease which is made worse by numerous environmental stressors that act together. The US Fish and Wildlife Service will decide in the next few years whether to list the western bumble bee under the Endangered Species Act.

Recently, dozens of western bumble bees have been documented by Oregon Bee Atlas participants across Oregon from the Klamath Mountains to the Blue Mountains, with several novel populations detected in the Cascades. Finding western bumble bees in Oregon can help its conservation in the future.

Reference:
Graves TA et al. 2020. Western bumble bee: declines in the continental United States and range-wide information gaps. Ecosphere 11:e03141.

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