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| What could be more moving? But the beams confuse migrating warblers and other birds - with potentially fatal consequences |
As part of the annual Tribute in Light commemoration of the terrorism attacks that brought down the Twin Towers, two blue beams will shine vertically into the sky.
Unfortunately, there has been a downside to the tribute which was established in 2002.
For unknown reasons, artificial light mesmerises many birds - especially fledgling seabirds and migrating songbirds - just as it does with moths.
Disoriented and exhausted birds are then at risk of crashing - with fatal consequences - into skyscrapers .
Birders, including members of New York Audubon Society, will be standing directly under the beams (which are visible from as far as 60 miles away).
They have secured an agreement with the tribute organisers to turn off the lights (comprising dozens of 7,000-watt bulbs) for 20 minutes every time 1,000 or more birds are circling or one that is exhausted falls to the ground.
In artificial light, it is hard to identify birds, but, to help the process, recordings will be made of their calls.
Species thought to be especially vulnerable include American redstarts, ovenbirds, black-and-white warblers and northern parulas.
The number of avian victims fluctuates from year to year according to the weather and phases of the moon.
In 2010, a new moon and cloudy skies yielded an estimated 10,000 birds caught through the night - the lights had to be shut down five times!
Photo credit: Anthony Quintano/ Flickr via Wikimedia Creative Commons.
* For more on the phenomenon of migrating songbirds being mesmerised by artificial light, Lighthouse Birdwatcher is available, price £1, via Kindle Books.
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