By T. Edward Nickens, contributing editor, Ducks Unlimited magazine (IG: @enickens)

I see the birds out of the corner of my eye, and my brain instantly processes the rate of their wingbeats, their relative body size, the color of their breasts. These calculations occur without a conscious thought. This happens every time I see a duck: What is it? Where are they going? Mallards, I figure, and the thought makes me smile. Headed north. Headed home. I keep my eyes on the sky, following the birds as they wing over the river, and then vanish into the treetops.

Right now, the skies are filling with ducks and geese and other birds on their northward migrations to their breeding grounds. These spring flights are at a more leisurely pace than those frantic autumnal passages, as the birds flee ice and snow. During the northward spring migration, ducks will stop for a week or two along the way. Pairs will often sequester themselves, feeding in the warmer waters of smaller wetlands where protein-rich aquatic invertebrates help them prepare for the rigors of breeding.

But leisurely or not, its a trek these birds can ignore no more than I could halt my own obsession with their movements. Lengthening daylight and warmer temperatures have a physical and psychological effect on birds. Its called zugunruhe, a German term that means migratory restlessness. It is an innate, ineluctable prompting that it is time to move, time to change, time to fly. Cage a wild, migratory bird during the lengthening days of spring and it will launch itself against its wire prison, frantic for the north. It cannot help itself. Zugunruhe.

Im feeling a bit of it myself, about now. A restlessness to reconnect. A disquiet in my spirit with these days of too little movement, and too little wildness.

But our time to fly will come. In a way, we are all overwintering in a season of challenge, hunkered down with our flocks. Yet it will not last. Our own feelings of zugunruheof constraint and inhibitionare as temporary as the winter. There is the promise of spring. There will be days of exuberant flight and freedom.

Out of the corner of my eye, the ducks remind me of it all.