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People look up at a flock of starlinas flying over the skyscaper Pirellone in downtown Milan.
Shiny skyscrapers define downtown cityscapes: reflective glass designed to mirror the passing clouds, giving the illusion of endless skies. For migratory birds, that illusion proves deadly: flying at full speed, they collide head-first – either dying on impact or falling to the ground where predators pick off an easy meal. And just as coastal lights disorient nesting sea turtles, so do urban lights lure night-migrating feathered travelers fatally off course.
According to Toronto-based FLAP Canada (Fatal Light Awareness Program), between 1.5 and 2 billion migratory birds die throughout North America each year, mostly from human-created problems. Although habitat loss is the leading killer, FLAP says, next in line is glass, especially in urban environments. Skyscrapers and multi-story office buildings are obvious culprits, but ground-floor lobbies, shop doors, plate-glass walls, car windshields and your windows at home also pose danger, according to ornithologists.
The problem is that birds recognize reflections as real space, not optical illusions. When a bird pecks and pecks at itself on the other side of your window, it’s attacking what it sees as another bird trespassing on its space.
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When a bird can see through a window, that bird is in serious danger if it sees houseplants. When light doesn’t reflect off the glass, the ficus in your office lobby looks like a landing strip, and birds will try to hone in on it at high speed. They either hit the glass, break their necks, and die, or stun themselves, fall to the ground, and become prey for other animals.
The contemporary urban landscape in the United States and Canada acts as a giant obstacle course for birds traveling to and from South America. North America is home to four major bird migration paths, or flyways: the Pacific, Central, Mississippi and Atlantic. Those flyways aren’t completely precise, but birders have used them for generations to track migrating species.
Scientists at the Cornell Lab of Ornithology recently found that some very small night-migrating birds follow an elliptical flight path, riding strong tailwinds in the spring and flying back against weaker headwinds in the fall. For night-migrating birds, many of which navigate by the stars, artificial light sources make the trip perilous. Light pollution, especially in urban areas, blots out most stars. The effect is like driving down an interstate where most of the exit signs have been removed. And if it’s cloudy, rainy, or both, FLAP’s researchers found, nighttime collision risk soars because the weather forces migrating birds to fly lower and much closer to buildings.
The American Bird Conservancy has developed guidelines for building designers and offers continuing education credits for members of the American Institute of Architects. The U.S Green Building Council offers LEED pilot credits for bird collision deterrence and making windows more bird-friendly. Some companies make special bird-deterring mesh or window glass that gives birds a visual cue not to fly into windows.
Designers and architects have discovered ways to make buildings less hazardous by adding external grilles, ceramic rods, louvres, photo murals, fritting, frosted glass or netting. Some cities that have adopted bird-friendly building policies or guidelines are San Francisco, New York, Oakland and Sunnyvale, California. In Oregon, Lights Out Portland encourages offices and homes to turn off lights during nighttime spring and fall migrations.
Part Of A Larger Problem
The Audubon Society says climate change is forcing birds to migrate farther north. A 2009 report compared where birds spent their winters over a 36-year period with the average January temperature in the continental U.S. during that time. As winters got warmer, some birds consistently wintered farther north. While the Audubon Society points out this doesn’t mean climate change is the only factor, the fact that the correlation is so strong can’t be ignored.
Together, Cornell’s Ornithology Lab and the Audubon Society created eBird, a real-time website where people can report bird sightings and locations. Scientists share this crowdsourced data worldwide to track bird migration and population.
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But when you add up all the deaths from whatever cause – habitat loss, collisions, pesticides, oil spills, waste pits, communications towers, predators, wind turbines, electrical wires – “human-related bird deaths may result in greater mortality than a population can withstand,” notes the U.S. Fish and Wildlife Service. The agency works with industry groups like the Avian Power Line Interaction Committee and the National Wind Coordinating Collaborative to try and minimize bird deaths.
FLAP offers an interactive map where people can report bird accidents worldwide.
How You Can Help
There are some simple things you can do around the house to help birds find their way. Some recommendations are as easy as closing your blinds so birds don't think they can fly through. You can also keep bird feeders at least 1.5 feet away from your home.
Office managers can install bird-proofing film and other deterrents on the building, or consider a lights-out policy on nights and weekends.
The Audubon Society offers more advice for making birds' paths a bit easier to navigate.