Oregon Department of Fish and Wildlife conservation biologist Susan Barnes called the failure to spot a single individual at 15 sites “moderately alarming.”

“It’s clear that there are not a lot of turtles out there, but it will take more years of data to understand what’s happening with local western pond turtles and why,” said Barnes, who oversaw the survey.

Pond turtle populations have declined throughout their West Coast range for a number of reasons, including destruction of their wetland habitat, conflict with invasive species and a recently discovered shell disease.