Alan Shabel, director of the Point Reyes Field Station and a lecturer at UC Berkeley, has never seen a mountain beaver with his own eyes, but he can read the signs, SFGATE reported.

In a lecture last week at the Red Barn Classroom in Point Reyes Station, Shabel described a 6-inch-wide burrow, arched at the top with a flat base, and plant clippings scattered around the underground homes. "They're very messy eaters," he said. "This is a charismatic creature that is very elusive." He said the sensitive subspecies has no known population estimate and is endemic to the area, meaning it lives nowhere else. The study he described relies on evidence of the animals rather than disturbing them, SFGATE reported.