How do the birds stay warm in winter?

NATURE NUGGETS

A white-tailed ptarmigan burrows in the snow to stay warm in winter in the high country of Colorado. DAWN WILSON PHOTOGRAPHY — COURTESY PHOTOS

An American kestrel fluffs up its feathers and pulls up a leg into its body for a little additional warmth on a cloudy winter day near Longmont.

Mountain bluebirds that have returned to Estes Valley early may still experience winter conditions, fluffing their feathers to stay warm.

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By Dawn Wilson

dwilson@prairiemountainmedia.com

A brutally cold few days arrive this weekend. The forecast calls for temperatures to drop into the negative teens at night on Sunday.

That is about 30 degrees colder than the average low temperature of about 16 degrees for mid-January in Estes Park.

People have fireplaces, heaters and warm blankets to stay cozy indoors during these frigid temperatures. But how do animals — particularly birds — stay warm during these deep drops in temperatures or even during the average cold and windy days of winter?

Although most birds that visit Estes Valley in the summer leave in winter, there are still several species, like pygmy nuthatches, black-billed magpies and Canada geese, that linger in Estes Valley year-round.

These hardy birds actually have several methods for staying warm.

The first example is of the white-tailed ptarmigan.

These denizens of the tundra live their entire lives either at or above tree line, including in winter.

To help them survive in this open landscape, they transition twice a year — in late spring they molt into their summer plumage of mottled gray and brown. In fall, however, they convert to white feathers, which help them blend into the snowy landscape.

Although this doesn’t help them stay warm, it helps them disguise themselves as they nestle into shallow depressions in the snow. This helps them hide in plain sight from predators, but the snow also acts as an insulator to help the birds stay warm in their cold terrain.

Another way birds stay warm in winter is to fluff their feathers to trap air.

The air gets trapped into pockets in the thousands of feathers on a bird’s body. By preening and keeping feathers healthy and flexible, the feathers can bend and move to create the pockets.

Some birds, like egrets and mourning doves, also have special feathers that crumble into a powder over time to help waterproof the feathers. Other birds use the oil from the gland at the base of their tail to help waterproof the feathers, thus preventing the bird from getting wet and cold.

A few bird species cuddle together for warmth in winter. Cavity nesters, like nuthatches, will gather in groups in a cavity or nestbox to stay warm.

Another way of cuddling together is to flock together or gather in roosts. Snow geese, Canada geese and even house finches will gather in large groups at night to break the cold wind and share a little warmth.

Finally, birds will tuck their feet — and bills — into their feathers or sit down to help keep the unfeathered legs warm. Although the legs may not have feathers, most birds have special circulation through their legs to aid in warmth.

To help birds get through the tough days of winter, consider putting out food for the local birds that provides high energy, like suet and sunflower seeds. Nest boxes may also be used by birds looking for a place to get out of the winter conditions.