Last Sunday evening found a handful of us Atlanta Audubon Society members sitting on the grounds of Grady High School in midtown Atlanta, keeping a close eye on the school’s big chimney.
We were doing a “swift sit,” keeping track of the number of chimney swifts coming in to roost for the night in the chimney.
With their summer nesting season over, chimney swifts now are congregating in communal roosts, gathering strength and numbers before they migrate south. Their roosting sites usually are large chimneys but may include some other man-made structures, such as old silos. Some roosts may consist of an extended family group of a half-dozen birds or so; larger sites can host hundreds or even thousands of swifts.
Many other bird lovers around the country also are doing swift counts this month and into early October. The sight of migrating swifts plunging into a chimney, as if drawn by a big magnet, can be exhilarating.
But the main purpose of a swift sit is to gauge how chimney swift populations are doing. Their numbers have plummeted by 50 percent during the past 40 years,
Sometimes called “flying cigars” because of their sleek, dun-colored bodies, chattering chimney swifts zip around above urban neighborhoods and scoop up untold numbers of mosquitoes and other flying insects.
In fact, the super-speedy birds are almost always in motion, splashing across a stream to drink and even mating in mid-air. They pause only to tend their nests and roost at night.
Deforestation and loss of large hollow trees as natural roosting and nesting sites caused chimney swifts long ago to adapt to chimneys and other man-made structures for survival.
Their small, strong feet and four sharp gripping claws make them uniquely able to roost in chimneys, especially the old-fashioned, masonry kind. They also are well-adapted to nesting in residential chimneys, using saliva to glue twigs to walls to form nests.
The problem now for swifts is modern-day chimneys, which are safer but metal-lined and topped with caps. The birds can‘t cling to metal surfaces or get past the caps.
More information: www.chimneyswifts.org.
IN THE SKY: The moon will be full on Thursday night, Sept. 19, the famed Harvest Moon.
Mercury is very low in the west just after sunset, said David Dundee, Tellus Science Museum astronomer. Venus is in the west just after dark and sets about two hours later. Venus and Saturn will appear close together Thursday night. Mars rises out of the east about two hours before sunrise. Jupiter rises out of the east just after midnight. Saturn is low in the southwest at dusk and sets shortly thereafter; it will appear near the moon Monday night.
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