In the still mornings of winter, when the air is humid and chill, the fog drifts across the lake in vapors of chiffon. If the sun is strong enough, the vapors fade into nothingness as the day advances. But if the fog is stronger, it thickens with the day, squeezing the land tightly along the shore, shrinking our vistas, fading the last golden colors of fall into shimmering gray. Such mornings are rare at the Fill, and not to be missed.

Yesterday morning, I thought the fog would triumph over the sun, making all the world silver. I dressed in my coats of many layers and hurried to the east end of Wahkiakum Lane, gateway to the Fill. The fog was so thick, it beaded in droplets on my binoculars. I started walking, able to find my way only because I have walked this trail countless times and cannot now go astray.

Ten steps past the Lone Pine Tree, I could dimly see the trees shrouding Boy Scout Pond as they loomed indistinctly over the Loop Trail. It was so quiet, I could hear the splash of a diamond drip of dew that condensed on the tip of a branch, trembled briefly, and then let go. The tiny plop it made when it landed on a poplar leaf was the sound of intimacy.

If you come on such a morning, you might think you are all alone in this gray world. But if you stop and listen, you can hear the scritch, scritch of a Spotted Towhee flinging leaf litter aside in gay abandon as it searches for seeds. Nearby, a Pacific Wren chitters a snatch of its song, then abruptly stops in mid-phrase. I guess it’s too cold to sing a full song, even for the world’s smallest, most accomplished tenor. The Song Sparrow who grew up in this grove rattles the bare branch of his favorite bush, gives one chirp to acknowledge me, then falls silent. In the distance of Main Pond, I can hear the American Wigeons talking to each other: “Tew-TEW-tew, tew-TEW-tew.” I wish I knew what it meant, but I do not speak wigeonese.

Birds on these mornings are everywhere heard but nowhere seen. It is a magical kingdom — for those of us willing to enter it.

Like fog clinging to moss, like smoke wafting over trees, the Barred Owl floats noiselessly to its favorite perch in the swamp: a cottonwood nook hidden from the prying eyes of its enemies, the crows and jays who are ever on the lookout for this silent predator.

Barred Owls have come to Yesler Swamp for the first time in history. If you search the branches near large tree trunks, you may find this new resident sleeping the day away. It will no doubt see you before you ever see it, blinking open its eyes to squint at you, checking to see whether you are harmless.

If you are quiet and respectful, the owl will slowly close its eyes again and go back to sleep. But in that moment when you lock eyes, you will discover why this owl has always been so mysterious to us.  Its eyes are black, with no visible pupil or any white rim, like two lumps of living coal. In them you can see nothing — or everything. In them you can get lost.

FUN FACTS ABOUT BARRED OWLS

• Barred Owls are not native to Washington. They have been slowly expanding their territory on their own, moving in from the east.

• In old growth forests, they are replacing our native Spotted Owl, probably because Barred Owls are more aggressive than Spotties, more omnivorous, and more tolerant of habitat degradation. In other words, Barred Owls are less choosy, so their opportunities for expansion are much greater.

• Barred Owls eat almost anything they can catch, including small mammals, other birds, amphibians, and even large insects. They hunt by hiding quietly in cover, then they fly out suddenly on silent wings.

• The feathers of the owls’ wings are fringed with tiny tufts that break up

• Barred Owls are monogamous. The female lays and broods the eggs, while the male hunts for her. When the eggs hatch, the female continues to keep the babies warm while the male hunts even harder to feed the whole family. It takes more than eleven weeks from the time eggs are laid to the time the babies can leave the nest.

• Owls cannot turn their eyes to look in different directions. Instead, they turn their whole heads. Owls have twice as many vertebrae in their necks as humans do and can turn their heads in a range of 270 degrees.

• Barred Owls hunt mostly at night, which is why they need their big eyes: to see in the dark.

• One way to find owls is to look for “owl pellets” under their roosting trees. Owl pellets are compressed balls of the indigestible leftovers from their food: bones, claws, fur, and teeth. These pellets must be regurgitated before the owl can eat again.

• When a Barred Owl is about to regurgitate a pellet, it stretches out its neck, opens its bill, and hacks. The pellet then drops out.