Juncos -- A sure sign of winter
They're back! My email box is bulging with notes this week announcing the return of dark-eyed juncos, the quintessential harbinger of winter. Call them juncos or snowbirds, their return means temperatures are dropping and snow will soon fly.
And they're right on time. They return each year in October and stay the winter. Their return north in April is a reliable sign that winter's really over. Juncos define the onset of winter, and their departure is April is good news for many observant nature watchers.
Dark-eyed juncos breed in northern forests all the way to the tundra. They find our temperate winters down right balmy. Permanent populations also live at higher elevations throughout the Appalachian Mountains. They nest in rhododendron thickets.
Juncos are among the easiest feeder birds to identify. The male's slate gray head, neck, back and upper breast contrast sharply with its snow-white belly and lower breast. In flight, white outer tail feathers flash conspicuously. Add a distinctly pink bill, and he's complete. Females are patterned similarly, but their dark parts are more brownish-gray.
This "slate-colored" dark-eyed junco is just one of five forms that occur across North America. Far western "Oregon" juncos wear a black hood that contrasts with a rusty back. The "white-winged" form of the Black Hills has two white wing bars and more white on the tail. The southern Rockies' "gray-headed" form has a bright rusty back. And the "pink-sided" form of the northern Rockies has broad pink sides. Hybrids of some of these forms occur, so watch for variations in the "slate-colored" form that occurs throughout the East.
According to the Cornell Laboratory of Ornithology's Project FeederWatch, juncos are usually seen at more feeders across the continent than any other species. They prefer white millet, cracked corn, and black-oil sunflower seeds scattered on the ground or on low platform feeders.
A few years ago I saw two juncos on an elevated finch tube eating nyjer seeds -- a first after more than 20 years of watching backyard feeder birds.
Winter flocks of juncos number 10 to 30 individuals. If you watch the juncos that come to your yard carefully, you'll notice two things.
First, you'll only see one flock at a time. Winter flocks defend feeding territories -- they don't tolerate intrusions from other flocks, unless it gets really cold and snowy. I've counted as many as 47 juncos beneath my feeders during a snowstorm.
Second, within a flock there is a definite social hierarchy or pecking order. Adult males occupy the top rung of the social ladder, followed by young males, adult females, and finally, young females. Dominant individuals eat first. Lower ranking juncos wait their turn. Early in the morning and late in the day, when feeding is most intense, you're most likely to observe aggression between dominant and subordinate individuals. Dominance is probably determined by a combination of age, gender, and experience.
When juncos head north in April, their instincts shift from winter survival to reproduction. Longer days trigger hormonal changes in males that induce them to sing a musical trill from the tops of the tallest trees. The monotone song is easy to recognize, though it might be confused with a chipping sparrow's song. Parallel hormonal changes in females make the males' song attractive, and pairing occurs.
Though males help gather nesting material, the female builds the nest alone. It's usually on the ground hidden under roots, a log, a rocky ledge, or an overhanging bank along a stream or road. The female lays four or five eggs and incubates them for about 12 days.
Thanks to fast-growing feet and legs, nestlings can leave the nest on foot when danger threatens as soon as nine days after hatching. Normally they begin to fly at 12 to 13 days. After the nesting season, which may include two broods, shorter days and plunging temperatures send them back to us for the winter.
The calendar may tell us winter's still weeks away, but the juncos are reminding us to keep the snow shovel handy.
For more information about juncos and a terrific new movie, "Ordinary Extraordinary Junco," visit www.juncoproject.org. The download is free.