Birds in Winter: How do they survive?

Written by Sally Sanders
Thursday, 15 January 2009 13:31

When the weather gets cold and snowy, many people wonder — even worry — about how the birds will survive.

For example, Jayne Rogers writes, “We live on Potts Pond, Weed Street, New Canaan where we have a nice winter population of mallard ducks.  In the last couple weeks, a pair of swans appeared on the adjacent pond.  We have seen swans there before but a couple years ago, one of a pair of swans was found dead by the side of the pond.  The birds just seemed to stay there frozen for too long a time and we felt terrible.  Is there anything that we should be doing to help this pair, or should we just watch and enjoy and hope they don’t freeze?”

Unless a bird is injured or ill, it should be left alone. Most birds that winter over — and Mute Swans are among them — follow their evolved instincts to deal with the weather. The swans need open water so they can root around under the surface for vegetation and, if they are healthy, should head south to the bays and inlets of nearby Long Island Sound if the pond freezes over. (If birds are injured or ailing, contact one of the wildlife rehabilitators listed at the end of the column for advice.)

An exception to the winter-savvy birds may be the Carolina Wren, a winter newcomer that is pictured with this column. This species, once quite rare here in winter, has been establishing itself as a year-round bird, but doesn’t seem to be as winter-wise as veteran, year-round species.  It tends to spend the night in cavities close to the ground, and consequently a deep snowfall can trap the bird, which then starves to death.

A big snowstorm can decimate a Carolina Wren population, which can take several years to re-establish itself. Probably the last time it happened here was in the 1990s.

Winter survival

Birds use a variety of techniques to deal with winter. Some, like the American Robin, change their diet to match the season. In the summer a robin feeds largely on worms and insects while in the winter, it eats berries and seeds. Some birds, like the Black-capped Chickadees, cache food in warm months to eat in the cold.

Birds that sleep out in the open in summer may seek refuge in cavities in the winter.

The Golden-crowned Kinglet epitomizes a bird that has learned techniques for winter survival. A tiny bird, the Golden-crowned Kinglet weighs only one-fifth of an ounce (six grams, which is less than some hummingbird species), yet it inhabits the woods of Maine throughout the winter. What’s more, it doesn’t eat seed, unusual for an overwintering bird.

How kinglets survive fascinated Berndt Heinrich, a professor, naturalist and wonderful writer. To uncover the secret of their diet, Heinrich shot a bird in mid-winter, opened its stomach and inspected its contents. He found it full of a tiny species of “hibernating” inchworm that the bird had plucked off branches. “Nobody had ever reported finding caterpillars on trees in the northern winter before,” he wrote. “But this bird and subsequent birds were proof of something new and unexpected.”

To keep warm, kinglets have plenty of feathers — Heinrich calculated that of its 0.403 gram of feathers, a female had only 0.095 gram devoted to wing and tail feathers. The rest — four to five times more weight than the flight feathers — were devoted to insulating the little body from the cold by holding in body heat. Like all birds in winter, they puff up their feathers to increase their insulating ability.

At night, while most birds sleep by themselves, kinglets huddle together in tree cavities to gain the extra warmth of numbers.

Voila!

Ben Oko of Ridgefield was pleasantly surprised the other day.  “Having just finished the Bird Notes in the Ridgefield Press, my favorite part of  the paper, I wondered longingly when and if  I would ever see one of the reported Pine Siskins exploding all over the state,” he writes. “Lo and behold, as I looked out of my kitchen widow at my feeder, there were five — count them, five — siskins feeding amongst a like number of goldfinches.”

Coming Up

Bird Seed Sale, benefiting conservation work, volunteers available to load your car, sponsored by Saw Mill River Audubon, Saturday, Jan. 17, 9:30 a.m. to 12:30 p.m., Pruyn Sanctuary, 275 Millwood Road (Route 133), Chappaqua, N.Y., sawmillriveraudubon.org.

Bald Eagle viewing, carpool trip to Shepaug Dam, Saturday, Jan. 17, 9:15 a.m., $5, Ridgefield Discovery Center, meet at Farmingville School, registration required, 203-438-1063.

On Feathered Wings, trip to photo exhibit at American Museum of Natural History, Saturday, Jan. 17, all day, $75/$85, Connecticut Audubon, 860-767-0660, pwood @ ctaudubon.org

Winter Walk in the Meadowlands of New Jersey, with Biologist and Naturalist Michael Newhouse and Bedford Audubon Society Director John Askildsen, Saturday, Jan. 17, 7:30 a.m. to 3 p.m., carpool from Bylane Farm, 35 Todd Road, Katonah, bedfordaudubon.org, 914-232-1999.

Nature Hike at Croton Point Park, Croton-on-Hudson with Bedford Audubon Society Naturalist Tait Johansson, Thursday, January 22, 9 to 11:30 a.m., carpool from Bylane Farm, 35 Todd Road, Katonah or join the group at Croton Point Park at 9:30, bedfordaudubon.org, 914-232-1999.

Birding Sachuest Point and Rhode Island Coast,  with Andrew Griswold, Harlequins and other winter ducks, etc,  Wednesday, Jan. 28, all day, $55/$65, Connecticut Audubon, 860-767-0660, pwood @ ctaudubon.org

Bird walks with Luke Tiller, mostly Saturdays at 8 a.m., $10 each; to register, www. sunrisebirding. com/ walks.htm;  203-981-9924, luke.tiller @ gmail.com.

First Sundays, birding at Greenwich Point with Meredith Sampson of Wild Wings, and other guides, Jan. 4, Feb. 1, March 1, April 5, May 3, meet at the second concession stand, 203-637-9822.

Copyright (c) 2008 by Jack Sanders. Send sightings or comments to: jackfsanders [at sign] yahoo.com, or to Bird Notes, Box 1019, Ridgefield, CT 06877; or call 203-438-1183, extension BIRD (2473), and leave a message with your report, spelling your first and last names and telling us your town. If you need help identifying a bird, try your local nature center. If you find an injured bird, call wildlife rehabilitator Darlene Wimbrow of Redding, 203-438-0618, Wildlife in Crisis of Weston, 203-544-9913, or Wild Wings of Greenwich, 203-637-9822. The columnist’s website is www. sandersbooks. com.