By Dr. Becker
Migratory birds face numerous threats along their perilous journeys. Habitat loss, hunting, wind turbines, and even electromagnetic fields can kill or injure birds, or throw them off course.
Many birds fly at night during their bi-annual migrations, using the moon and stars for navigation. Light pollution – the glow created by artificial light from cities and buildings at night – poses another serious threat to birds flying nearby.
Bright artificial lights disorient migrating birds, often drawing them toward the light. They may collide with buildings and other disoriented birds, and some, reluctant to leave the brightly lit locales, die from exhaustion after circling lit-up buildings.1
Artificial Lighting Puts Migratory Birds at Risk
More than 450 bird species, including many that are threatened or endangered, migrate at night, putting them at heightened risk of colliding with artificially lit buildings and towers.
In addition to buildings, lighthouses, floodlights, festival lighting, and airport ceilometers (beams of light used to determine the altitude of clouds) put birds at risk. According to Fatal Light Awareness Program (FLAP) Canada, a bird has a 43 percent chance of colliding with a human-built structure somewhere along its migration path.2
Light beams, such as those used in the “Tribute of Light” memorial at Ground Zero in New York, can be particularly dangerous even without a collision risk, as birds become “trapped” inside the beams of light.
As FLAP noted, the birds may become reluctant to fly back out into the dark sky, instead circling inside the light beams until they drop from exhaustion.3 The consequences can be catastrophic. As reported by National Geographic:4
“Sometimes whole flocks collide with over-lit structures. According to [Michael] Mesure, [executive director of FLAP], over two consecutive nights in 1954, 50,000 birds died at Warner Robins Air Force Base, Georgia, when they followed lights straight into the ground.
And in 1981, over 10,000 birds slammed into floodlit smokestacks at the Hydrox Generating Plant near Kingston, Ontario. Seabirds are also at risk, said Bill Montevecchi, a marine ornithologist at Memorial University of Newfoundland, in St. John's, Canada.
Some, like the tiny Leach's storm petrel, feed offshore on bioluminescent plankton — so are particularly drawn to light. The birds may be fatally attracted to lighthouses, offshore drilling platforms, and the high-intensity lamps used by fishermen to lure squid to the surface.”
New York State Dims City Lights to Protect Birds
Earlier this year, New York State joined the National Audubon Society's Lights Out program, which asks building owners and managers to turn off excess lighting during the months migrating birds are flying overhead.
According to New York Governor Andrew Cuomo, bright outdoor lights will be turned off between 11 p.m. and dawn during the peak migration seasons in spring and autumn. Several New York landmarks, including the Rockefeller Center, Chrysler Building, and Time Warner Center, already participate in the Audubon program.
Other major cities around the US also participate in the program. Chicago, IL initiated the first Lights Out program with the Audubon Society in 1999, and since then programs have begun in San Francisco, Washington DC, Indianapolis, Boston, Minneapolis, Milwaukee, and more.
As part of the “Lights Out Chicago!” program, for example, the Chicago Bird Collision Monitors (CBCM) encourage building management and the public to turn off bright lights from 11 p.m. until sunrise during spring migration (March 15 to June 15) and fall migration (August 15 to November 15). They recommend the following tips:5
Turn out lights Put motion sensors that activate lights only when rooms are occupied Put lights on timers Draw shades or blinds Use localized lighting at reception desks rather than illuminating an entire multistory lobby Schedule cleaning crews to work before 11 p.m. so that lights can be turned out for the rest of the night Dim lobby lights in the early morning hours to the greatest extent possible
Other bird-friendly initiatives are also underway. For instance, it’s estimated that collisions with communications towers kill more than 6 million birds each year. Conservationists, the Federal Communications Commission, and the Federal Aviation Administration are working together to reduce these deaths, and there may be a relatively simple solution.
Research suggests the red glowing lights on many such towers confuse birds, leading to collisions and circling, while flashing strobe lights do not pose the same risk. It’s estimated that replacing red lights on communications towers with flashing strobe lights could reduce bird deaths by 75 percent while preserving aircraft safety.6
You Can Help by Reducing Light Pollution in Your Backyard
In the US, the Migratory Bird Treaty Act makes it illegal for anyone to take, possess, sell, or purchase any migratory bird (or their nests or eggs), unless a special permit is issued. However, the birds are still in need of added protections.
The US Fish and Wildlife Service (FWS) has a plan to strengthen the treaty to better fit the threats that have emerged in the 21st century. If you want to get involved, the Audubon Society has a sample letter you can use to let FWS know you support this important action.
You can also make your backyard a more bird-friendly place by creating an area with natural habitat, including native grasses, shrubs, and trees, for birds to find refuge, especially if you live in an area that's highly developed (or surrounded by lawn "deserts").
Add in a source of water and food for the birds, minimize your use of pesticides and other garden chemicals (including fertilizers), and consider these additional tips to make your yard "bird-friendly":7
- Install bird nest boxes, which provide nesting areas even in urban areas
- Reduce window collisions; place bird feeders within three feet or at least 20 feet away from windows, and hang mylar tape strips from windows that are frequently struck by birds
- Create a brush pile: A pile of downed tree limbs or other yard brush can provide an important refuge for birds during bad weather
- Lights out from dusk until dawn: Minimize your contribution to light pollution by turning off outdoor lights at night (or using them only with a motion sensor). Outdoor lights should be pointed downward with “shields” designed to prevent the light from traveling sideways (which will also keep the light off your neighbor’s yard).
Choose lower wattage for your light bulbs and use dimmers. You can also close your curtains at night to prevent indoor light from escaping outdoors, and if you live in a multi-story building, use blackout curtains to prevent bird collisions.8