The nest sits in the middle of the hawthorn in front of us, silent and inscrutable. We contemplate it, tucked securely among thorny branches, at the edge of a frozen slough near the Bitterroot River. Perhaps it contemplates us, too. It’s a flat, mossy cup, larger than my two fists. Our question today is simple enough: whose nest is this? But if we hope to find an answer, we’ll have to use all our powers of observation and imagination.