For almost a decade I looked at wildlife tracks with my friend Sonnie, at first casually and then seriously, as we helped monitor black bears and mountain lions in New Mexico for a southwestern environmental group. Sonnie had health problems, and the pace of identifying track and sign suited her well. A slow walk, stop, bend, look. Four dainty toes, suggestion of fur, and that wavy line at the bottom of the palm pad? A gray fox passed this way. Over here: four teardrop toes, one middle toe extended past the other, palm pad more than two inches long? Mountain lion, possibly male.

This weird squiggle. Darkling beetle. A sinuous curve with smudges on either side. Some kind of lizard.

One spring day Sonnie turned to another friend with whom she was hiking, or likely strolling, musing, bird watching, and said, as I have often heard her say, “It’s so beautiful here,” before she fell to the ground. She was gone in that instant. Her memorial, long delayed because of COVID-19, featured a ravishing blue sky of cumulus clouds and a red-tailed hawk. I quoted from Aldo Leopold, a seminal environmentalist she had often quoted, too: “There are some who can live without wild things and some who cannot.”

Sonnie knew which one she was.

What Walks This Way: Discovering the Wildlife Around Us Through Their Tracks and Signs