The trees take shape as we push the canoe into the swamp and walk it through a dense mat of vegetation. They are three tall cypress trees that rooted, decades ago, atop an old beaver dam. The dam no longer holds the water back, and now the trees create a distinct outline, like a curtain across the swamp.

As we clamber into the canoe, there's just enough light to cast the trees in silhouette-tall, black shapes against the lightening sky, accompanied by a meager impression of cypress knees below, rising from the muck like fangs. That's where we'll wait for the ducks. That's where we've hunkered down more times than I can count. Over the years, the silhouette of those trees in the light of dawn has become one of my most detailed memories. I could sketch them now. Their serrated black shapes remain as sharp in my imagination as they are in real time.

I've had silhouettes on my mind lately. Though my recollections of last season's hunts tend to soften, some remain in detailed focus. I'll never forget that final duck of the season-a single greenhead sailing into a rice field against a blue sky. Memories of other hunts get mixed together, stirred by long days afield and sleep deprivation. Oddly, I remember certain silhouettes-those three cypress trees; my son, Jack, paddling the canoe; and geese coming into a pond at dusk, their dark outlines mirrored in the water below.

Silhouettes have long been associated with love and loss and the act of remembering. In the 18th and 19th centuries, paper silhouettes of human subjects, also called "profiles," were all the rage. These silhouettes speak to a certain kind of familiarity, as two-dimensional proof that the outline of a loved one can bring to mind the person in whole. A silhouette is a suggestion of reality. It forces the mind to fill in the blanks in an exercise that seems to only strengthen the power of memory.

In the swamp, I have silhouettes on my mind for other reasons. The silhouette of the tree line sometimes causes me fits. Early birds vanish against the dark trees, only to reappear when silhouetted against the water. We hide the canoe and pile it with branches to break up its outline. I've become ever more aware of our profiles while hunting. Watching videos shot by drones has changed the way I hide in a swamp or marsh. From a duck's-eye view, a well-camouflaged pair of blobs in the brush or marsh is nonetheless a pair of blobs to be avoided. Breaking up your silhouette is crucial, no matter how modern your camo pattern is.

And there's another reason that I've been pondering silhouettes. Unless I prove to be a miracle of modern medicine, I've got more duck seasons in the rearview mirror than in the road ahead. It's a calculation that has caused me to reconsider how I spend my time and energy. I'm not slowing down, at least not much. Thanks to the titanium in my right knee, I'm still hauling canoes through the woods and mucking around in the marsh goo. But the essence of things matters more now than ever.

This understanding has made me a better duck hunter. I don't want to waste a sunrise by giving it less than 100 percent. Every hunt has the potential to be one of those that burns itself into memory. That realization comes back to you day, night, spring, summer, fall, and winter to race your pulse and inspire the next four a.m. alarm.

There's a lot of water in front of me before I get to the place where I'd rather remember past duck hunts than make more memories. These days, I want every hunt to be filled with friends or adventure or feathers. Like the silhouette of those three cypress trees in the beaver swamp, I want to fill in the outlines of every hunt with details that I will never forget.