LINCOLN, Neb. (AP) — A crew cutting down a dying oak at the University of Nebraska made a surprising find — flying squirrels.

A video shot by a member of the crew made its way to Larkin Powell, a conservation biology professor. The Lincoln Journal Star reports that he was surprised by what he saw — the only remaining Nebraska population of the nocturnal and tiny animals was 90 miles away in Nebraska’s southeast corner, near Indian Cave State Park.

It turns out the flying squirrels had been living undetected — until now — in the treetops just above the animal experts at the university’s School of Natural Resources in Lincoln. The crew made the discovery earlier this month, the newspaper reported.

Powell was surprised by their presence, if not by their elusiveness.

“It’s among the species that’s harder to document because they’re not out when people are around,” he said. “And they’re little dudes.”