Birds slowly prepare for winter

Just a few months ago, the prime aim of most birds was to breed and make babies. Decked out in their bright breeding plumage of spring, male songbirds sang their hearts out for much of the day to attract mates and defend territories. Females were intent on nest-building and egg-laying.

Now, with the nesting season over and the first hints of fall in the air, the birds’ main goal is to prepare for winter. Most males have abandoned their glorious songs of spring and have fallen silent, except for unimpressive “chipping” calls. Males and females are molting, replacing summer’s ragged old feathers with new ones. (Wing feathers are shed only one at a time on each wing, and new feathers grow in before more are dropped so that the bird can still fly.)

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When chimney swifts flock to their winter home, Venezuelans welcome the ‘vencejo de chimena’ as their own.

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Many songbirds also are becoming less aggressive and territorial now that they’re in the post-breeding season. Soon, many of our year-round birds — cardinals, blue jays, titmice, Carolina chickadees and others — will become sociable to the point that they form loose flocks to better protect themselves from predators and forage for food during the winter.

Gathering in flocks, too, will be the so-called neo-tropical migrants, which represent as many as half the state’s summer nesting birds. The shrinking daylight hours and cooler weather are cues for them to get ready to head south for winter grounds in the Caribbean, Mexico and Central and South America. By flocking together, their arduous journey may be made a little safer.

The communal instincts of chimney swifts, for instance, are kicking in now and soon they will be congregating in flocks of hundreds or even thousands at roost sites, such as large chimneys of old buildings. By mid-October, most of Georgia’s swifts will be gone to spend the winter as far south as Venezuela and Peru.

So, during the next few weeks, many of the migratory birds should be stopping at backyard feeders and birdbaths, although their colors probably won’t be as brilliant as when they visited during spring migration and were getting ready for the nesting season.

Many birders, though, say that fall migration is almost always better than spring migration. One reason is that we get more birds in the fall, mainly because juveniles that hatched out in spring and summer are now heading south for the first time. We also may get more unusual birds. One reason is that hurricanes and tropical storms this time of year may blow many birds far afield.

Migration notes

Even though many of Georgia’s migratory songbirds are here for only four or five months in spring and summer before heading south again in the fall, we tend to call them “our birds.” But in the birds’ winter grounds in the Caribbean and Latin America, folks there regard them as their birds, even calling them by different common names.

The chimney swift, for instance, is known as the “vencejo de chimena” in Venezuela, where it spends the winter. Our scarlet tanager becomes the “escarlatina” when it flies into Puerto Rico for the winter. The wood thrush becomes the “zorzalito maculado” in Mexico. The yellow-throated warbler is the “reinita gorjiamarilla” at its winter home in Costa Rica. The ruby-throated hummingbird is the “chupaflor rubi” in Guatemala.

Gardening ideas

When we travel, we usually have many restaurants and gas stations en route. But migratory birds are having increasing problems finding stopover places where they can rest and refuel. More and more land is being developed and paved over, wiping out trees, shrubs, flowers and other plants that provide food and shelter to the traveling birds. But we can help the birds, by creating gardens that provide safe stopovers with plenty of food, water and resting spots.

So, want some first-hand tips on how to make your backyard a sanctuary for birds — and for butterflies and other creatures as well? You can see how several folks have done it this Saturday during the Atlanta Audubon Society’s 2008 Backyard Wildlife Sanctuary Tour.

This year’s tour will include five backyard sanctuaries in Smyrna and Mableton in Cobb County and, as a bonus, a private sanctuary in Kennesaw and the Smith-Gilbert Arboretum that was a gift to the city of Kennesaw last year. The 13-acre arboretum, which includes a collection of some 3,000 trees, shrubs and other plants, was initially intended to be a bird sanctuary.

For ticket information and directions, visit the society’s Web site at www.atlantaaudubon.org or call 770-913-0511.

In the sky

The moon will be a thin crescent in the northwest just after sunset on Monday. By the end of the week, it will have “grown” into a first quarter moon, says astronomer David Dundee of the Northwest Georgia Science Museum. Mercury and Venus are very low in the west just after sunset. They will appear near the moon Monday evening. Mars sets in the northwest just after sunset and appears near the moon on Tuesday evening. Jupiter rises out of the east before sunset. Saturn won’t be observable until the end of September.