OAKLAND, Calif.— The Center for Biological Diversity filed a formal notice today of its intent to sue the U.S. Fish and Wildlife Service to protect imperiled Suckley’s cuckoo bumblebees under the Endangered Species Act.

These unique, parasitic pollinators are threatened by habitat degradation, overgrazing, pesticide use, climate change and declines in their host species.

Suckley’s cuckoo bumblebees were once common in prairies, meadows and grasslands across the western United States and Canada but have lost more than 50% of their historic range. The last sighting of the bees was in Oregon in 2017. Over the past two decades a few scattered individuals have been spotted in California, Alaska, Idaho, Oregon, Colorado, Wyoming and Montana.

“The Suckley’s cuckoo has such a fascinating life history and plays an underappreciated role in the health of the ecosystem,” said Jess Tyler, a staff scientist at the Center and a petition co-author. “We must act quickly so we can save this bee, before it’s too late.”

In April 2020 the Center petitioned to protect Suckley’s cuckoo bumblebees under the Endangered Species Act. The deadline for the Fish and Wildlife Service to make a final listing decision was April 2021. But it took the agency until May 2021 to even begin an initial status review to determine whether the species warranted further consideration for protection.

Today’s legal action comes two days after the Service found that the Center’s 2021 petition to list another cuckoo bumblebee — the variable cuckoo bumblebee — presented evidence warranting a 12-month status review of that species. Variable cuckoo bumblebees and Suckley’s cuckoo bumblebees are separate, unrelated species.

The survival of Suckley’s cuckoo bumblebees is dependent on the welfare of their primary host, western bumblebees, who have declined by 93%. The Center is also working to obtain Endangered Species Act protections for western bumblebees.

Suckley’s cuckoo bumblebees take over the nests of their host, tricking the host’s worker bees into caring for their young. Through that process cuckoo bumblebees create greater species diversity and health among bumblebee communities.

“Every day the Service delays protections pushes Suckley’s cuckoo bumblebees closer to extinction,” said Kylah Staley, a legal fellow at the Center. “This extremely rare and important species cannot wait any longer.”

Background

The decline of Suckley’s cuckoo bumblebees is part of a troubling downward trend in many of the 46 species of bumblebees and approximately 3,600 species of native bees in the United States that are needed to pollinate the full spectrum of wild plants. These generalist pollinators are among a rare group of parasitic cuckoo bumblebees that play important regulatory roles in bumblebee communities and ecosystems.

While their specific methods remain unknown, female Suckley’s cuckoo bumblebees must fight or sneak into a host colony, then kill or subdue the host queen. The cuckoo bee then lays her own eggs and controls the workers to continue collecting pollen and nectar to feed her offspring.