The twin beams of the annual 9/11 Tribute in Light memorial were shut down late Saturday after about a thousand confused birds flew into the powerful lights.
The lights were turned off at about 11 p.m. and turned back on about a half-hour later. Some birds returned the second time, but not as many as before.
Members of the New York City Audubon Society have monitored the memorial for years to make sure the lights don't disturb birds, according to the group's website. People at the scene Saturday who said they were with the Audubon Society said they ordered the lights turned off after birds swarmed to the beams.
The lights are not at Ground Zero, but on top of a parking garage in Battery Park City. The lights are supposed to stay on until 6 a.m., a New York City police officer at the scene said.
"For many New Yorkers, these twin towers of light are an evocative, poignant memorial to the thousands of precious lives lost on that terrible day," the Audubon Society says on its website. "What most do not know, however, is that NYC Audubon and the Tribute's organizers have continuously worked together to mitigate a possible danger to some of New York's most vulnerable and largely unseen visitors: night-traveling migrants."
The group says birds were similarly attracted to the lights in 2004, when "multiple observers counted thousands of birds fluttering in the light columns, seemingly unable to break away - and in danger of depleting crucial fat reserves needed to carry them to their southern wintering grounds."
Since then, the city Audubon group and the Municipal Arts Society, which organizes the tribute, "have designed a plan in the event such a phenomenon recurs," the website said.
With Christopher Pasatieri