It was bright winter sun and -1 degrees when we skied out to Camp Solitude, shushing across the lake to the island on snow so cold it whispered. After starting a fire in the cabin woodstove, we went exploring around the frozen bog and backwaters. Two ice fishing shacks stood deserted near shore. Except for a father skiing a mile away with a brown Lab and two young children, there was no one on the lake.

We stayed in the lee of the islands, following a pattern of dog-like tracks that I thought were coyote. Four toes with nail marks. A canine that was walking, not running; but unlike a well-fed domestic dog that romps around, these tracks went in a straight, purposeful line. The stride - the distance between each footprint - was too short to be a coyote. Fox, then. The tracks led to a small stump near shore, a perfect spot for a red fox to scent mark with urine. There was none. The prints veered away again across the lake. I looked closer. The tidy dog prints were less than two inches wide, and each step moved the canine no more than 8 inches.

Back at my desk, I recreated the track and pattern, got out the ruler and measured the possibilities. They were too small even for a red fox, leaving only the elusive gray fox, a night hunter who likes corn and apples as well as mice and is capable of climbing trees, where it has been known to nap in abandoned hawk nests. Once found only in southern Maine, the gray appears to have made its way to Waldo County.

Christine Parrish is working on an e-book about working in the Wyoming wilderness.