ASHEVILLE, N.C.— In response to a petition and lawsuit from the Center for Biological Diversity, the U.S. Fish and Wildlife Service today proposed to protect tricolored bats as endangered under the Endangered Species Act. But the agency failed to designate critical habitat for the imperiled bats.

Tricolored bats are among the smallest bats in eastern North America — and among the most imperiled. In the past two decades, their populations have declined by 90% across most of the species’ range; one-third of colonies have disappeared entirely. They weigh less than a sheet of paper, yet each individual bat consumes up to a million insects per year, helping to control mosquitoes and agricultural pests.

“Tricolored bats are barely clinging to survival, and it’s high time to protect them,” said Will Harlan, a scientist at the Center. “White-nose syndrome is a devastating pandemic that has killed millions of bats. I’m thrilled that these tiny bats have finally been granted endangered species protection.”

The primary cause of tricolored bats’ steep and sudden decline is white-nose syndrome — a fungal disease that has spread across the species’ entire 39-state range. The fungus invades the bats’ skin, often during hibernation, causing them to wake up too soon, depleted of the resources they need to survive winter.

The Fish and Wildlife Service also identifies climate change and habitat loss as key threats. Tricolored bats rely on mature and old-growth forests with closed canopies for roosting and foraging, so logging and forest loss threaten their habitat and survival. Despite this the agency has declined to designate critical habitat as required by the Endangered Species Act.

“It’s baffling that the Fish and Wildlife Service acknowledged that habitat loss is one of the biggest threats to the tricolored bats’ survival but decided not to designate any critical habitat for them,” said Harlan. “These bats urgently need their homes protected to stop them from going extinct.”

Wind turbines are also cited as threats to tricolored bats, and the Fish and Wildlife Service endorses a solution that is already readily available: Curtailment of wind turbines at slow speeds when bats are flying can significantly reduce bat mortality.