WE SAW mule deer by the dozen, numerous squirrels, a porcupine and fresh bear scat. But my only encounter with wildlife was with a mouse.

We had hiked seven miles down from a mountain called Bunker Hill, dropping 3,000 feet to a camp along the East Fork of the Pasayten River that drains north into British Columbia. Rain pattered on the tent fly. Wet wool can be dried if left overnight in the bottom of a sleeping bag, and my wool socks were wet. In they went, and me after them.

In a few minutes, I woke up kicking an imaginary snake off my legs.

"What a dream!"

Jim Roepke, who had been snoring next to me in the instructor's tent, rubbed the new bruise on his leg.

My socks twitched on my legs again; I pushed them off me.

A third time they crept back, like socks in a cartoon. A third time I squirmed away, unable to believe that there was anything in my sleeping bag but strangely animated hose.

Unable, that is, until I felt the tickle of little feet.

Bolting upright with a scream, I jerked my legs back, grabbed a light and moving slowly, I started back down the tunnel of nylon, head first, like a spelunker venturing into a treacherous cave.

Nothing at first. Then the light found . . . a tail. Hearing my muffled cry ("There"s something alive down here!"), the two NOLS instructors in the tent, rugged paragons of wilderness expertise, clutched their sleeping bags around their legs. I moved the beam up the tail, inch after inch, four inches in all, until it was shining directly on a pair of beady, black, terrified eyes.

Even experts have a hard time telling the mouse species apart. His tail was long enough to be a long-tailed meadow mouse, his ashy fur the proper color of a heather vole. He bore a resemblance to the Oregon meadow mouse too, and the northern bog vole, proud possessor of different-colored upper incisors.

Fortunately I was spared the sight of any teeth. The beast squeaked miserably in a fold of nylon. I felt half sorry for him, despite the adrenalin he had unleashed in my bloodstream. He had ridden down from Bunker Hill and his home, all his friends, relatives and favorite restaurants up in the Hudsonian zone were utterly lost. His new life would not be easy. Shooing him off, into strange woods full of weasels, coyotes and flammulated screech owls, I wished the little begger well.