At 907 Fifth Ave., on the southeast corner of 72nd Street across from Central Park, at least 10 roosts for sparrows are nestled in the balustrades under the third-floor windows.

These sparrows have flown under the radar, despite a storm of controversy about the city’s most famous avian resident, Pale Male, a red-tail hawk that was evicted in 2004 from his regal roost atop the center window of the top floor of 927 Fifth Ave., two blocks to the north. The battle over Pale Male’s nest, which was removed by the building’s board of directors only to be rebuilt after a tremendous public outcry, is a veritable legend of New York.

For the sparrows at 907 Fifth Ave., however, life has been quieter. A. Laurence Kaiser Jr., the head of Key Ventures Inc. and one of the city’s most knowledgeable people about luxury apartment buildings and their denizens, recently sold one of the apartments right above the sparrows’ balustrades and maintains that the purchaser was aware of the nests and not in the least concerned.

There are five “nested” balustrades on the Fifth Avenue façade and another five on the 72nd Street façade of the 12-story building, which was designed by J.E.R. Carpenter and erected in 1916.

Each of the five-column balustrades appears to have nests along its entire length, suggesting either multiple nests in each balustrade or perhaps the largest and most palatial sparrows’ nests in the city.

While it is clear that twigs and other nest paraphernalia are heaped up at the base of each column in the balustrades, the sweet, small, feathered beings are not always in evidence.

This season, a flurry of sparrows darting in and away from the nests often can be seen shortly before 4 p.m.

Last Friday, National Pigeon Day was celebrated in Central Park, and the pesky, waddling birds acted, as usual, as if they owned the city. The city’s hoppity sparrows, on the other claw, are obviously good-natured and should not be confused with the vultures of Wall Street.

According to the Web site birdsandbuildings.org, every year 1 billion or so birds fly into windows across the country. “Birds don’t see or understand windows and reflections … they see images that signal a flyway — and they fly into the glass,” the site says.

It also mentions Chicago’s “Design Guide for Bird-Safe Buildings,” including the use of visible structural details, reduced reflection of vegetation, angled glass, fritted glass, awnings, and interior artwork. Such guides, however, tend to be architecturally constrictive, especially in an age when the spectacular new Olympic Stadium in Beijing, designed by Herzog & de Meuron, resembles a birdcage.

Perhaps Mayor Bloomberg should promote the purchase by apartment dwellers of birdhouses.

Mr. Horsley is the editor of CityRealty.com.