On a tromp through the woods on a cold winter day, bird-watchers always perk up when they hear loud, cheery chickadee calls ("da-Dee, da-Dee, dee-dee"). Chickadees are fine birds, and always welcome, but at the moment we're more interested in other birds that might be traveling in their entourage.

These often include nuthatches — both the red-breasted and white-breasted variety — and maybe a brown creeper or two, a downy woodpecker, and, if we're especially lucky, the biggest prize of all, some golden-crowned kinglets. These tiny forest birds might just be the most challenging songbirds to find in the winter and few of us ever do.

Tiny and tough

Gram for gram, kinglets are the hardiest birds in the winter woods. Even if you consider yourself very robust and spend a lot of time outdoors, these tiny birds could make you feel like a wimp.

At 4 inches long and tipping the scales at about 5 grams (the weight of a nickel), golden-crowned kinglets are the smallest winter bird in Minnesota. Their equally tiny cousins, the ruby-crowned kinglets, migrate away to southern states. By the laws of physics, golden crowneds are almost too small to survive the cold, especially when you consider their specialized diet.

Golden crowneds consume insects, and these are scarce in winter. In fact, nearly all insect-eating birds, including swallows, purple martins and warblers, migrate away because their food source disappears at the end of summer. But golden-crowned kinglets flood down from Canada because they know the secret for success at our latitude: consuming dormant insects, and tiny, winter-active species such as springtails.

Because they're so small, kinglets have to work harder to maintain their internal temperature than larger birds do, and long winter nights are especially challenging. They make it through 15-hour nighttime fasts by huddling together to share body warmth and by shivering constantly, conserving the heat this generates by fluffing out their feathers.

A bright crest, dramatic eye markings and standout wing bars on a 4-inch bird add up to a golden-crowned kinglet.

At dawn, golden crowneds head out to begin the all-day hunt for food, since they must eat constantly to maintain their metabolisms. Conifers are their preferred haunts, since the needles often hold tiny, inert moth caterpillars. The micro birds dart from twig to twig, even hovering like hummingbirds to snatch at larvae. They never stop, since a hiatus of even two hours could be fatal.

Living on the edge

Kinglets live very close to the edge and their survival rate is low — only about one in six birds lives longer than a year. They have to do everything just right, and then enjoy a dose of good luck to make it through each winter day. Joining a mixed flock of birds led by chickadees is a good tactic, since more eyes help increase the odds of finding nourishing food (and avoiding predators). The various species in the mixed flock don't directly compete for insects, since their beaks are adapted to different foraging styles.

Kinglets are in constant motion, hopping and hovering, calling to each other continually with high-pitched "tsee, tsee" notes, another survival tactic. It's not a good idea to stray very far from other golden crowneds, because, like in a game of musical chairs when the music stops, as darkness falls, they need to meet up quickly and find shelter for night's huddling.

Heard more than seen

More bird-watchers hear golden-crowned kinglets than ever see these elusive little birds. Many train themselves to recognize that contact call, and when they hear it they begin searching nearby spruces and firs for signs of activity. The kinglets are usually high in the trees and back in the middle of a grove, making sightings a challenge.

But suddenly someone may spot a flash of orange or yellow on a small bird's head, or a white eyebrow with a black line above it. "Kinglets," he or she will shout, and everyone will gather, hoping for a glimpse.

Typical of insectivores, golden crowneds are almost never found near bird feeders. But if you head out to a wooded area with plenty of conifers, you might get lucky. Listen for chickadee calls, then watch for a flock of active birds to flit into view. Mixed in there just might be these forest sprites, the hardest-working birds in the winter woods.

St. Paul resident Val Cunningham, who volunteers with the St. Paul Audubon Society and writes about nature for local, regional and national newspapers and magazines, can be reached at valwrites@comcast.net.