Hundreds of birds migrating through New York City earlier this week were killed when they collided with the World Trade Center buildings, creating a cemetery of winged carcasses on the streets below.

On Tuesday morning, Melissa Breyer, a New York City Audubon volunteer, was collecting the bodies of migratory birds who had died colliding with into the glass towers in downtown Manhattan.

Breyer tweeted that in just over an hour she picked 226 tiny lifeless bodies off the sidewalks around the World Trade Center.

She said thirty were still alive and were transferred to the care of a wild bird rehabilitation center for veterinary aid.

"When you have 226 dead window-struck migratory birds from one morning, it's hard to get them all in one photo," Breyer wrote on Twitter, with a picture showing dozens of dead birds, many of them warblers, in all shades of yellow, brown and grey.

"Lights can be turned off, windows can be treated. Please do something," she wrote.

Associate director of conservation and research at NYC Audubon, Kaitlyn Parkins said:  "They can turn down the lights at night to assist prevent light collisions."

"Alternatively, you can treat reflective glass to make it appear solid to birds."

A similar incident was reported last spring when hundreds of songbirds were killed when they collided with a see-through barrier in Manhattan's Liberty Park.

Following the incident, the Port Authority of New York and New Jersey put bird-friendly stickers on the glass.

Parkins said the mass bird fatalities this week were most likely caused by a "huge pulse in migration" on Monday, Sept.13.

"Birds are driven off course by light pollution. They're often attracted to bright city lights," Sirena Lao, a researcher at the San Francisco Bird Observatory, told NPR earlier this year.

"So birds will veer off course and fly towards these cities, which leads them to even more hazards."

Responding to Breyer's tweets, The World Trade Center released a statement thanking her for bringing the issue to the facility's attention.

"We are actively encouraging our office tenants to turn off their lights at night and lower their blinds wherever possible and are investigating additional precautions," the company wrote.

Dead bird Representation image. Pixabay.