Dark Sky for Birds
Written by ABNC Biologist and Ornithologist, Chris Smith
Spring migration is upon us! Migratory birds typically travel to their breeding habitats from March 1st to June 15th. Their migration peaks between April 23rd and May 10th.
Perhaps you have a bird feeder, a water feature, or otherwise maintain a bird-friendly landscape by planting natives and minimizing the use of pesticides. If you do, you are ensuring that the birds have a place to rest and forage during their migration on the Central Flyway. Thank you! But did you know: you can do more.
Photo by Gary Seloff of cedar waxwing at ABNC
Increased urbanization has led to a reduction in bird populations around the world. This is partially due to habitat loss, but there is also another important component, one over which we have direct control - light pollution. It is estimated that structure collisions cause one billion bird deaths annually in the U.S. In our region, lights from homes and businesses have led to record high death rates for migratory birds. Birds that migrate are at the highest risk of colliding with buildings and structures.
How do lights affect birds? The Florida Atlantic University Astronomical Observatory explains what happens:
“Many species of birds, especially the small insect-eaters, migrate at night. Migrating and nocturnal birds will use the light from the Moon and stars and the setting Sun for navigation during their bi-annual migrations. Light pollution hides their navigational aids. Artificial, city lights especially interfere with this instinctive behavior. It draws night-migrating birds toward brightly-lit buildings in urban areas. The Fatal Light Awareness Program reports that researchers have used radar imagery to determine how birds respond to lit environments. They observed that once birds fly through a lit environment, they’ll return to that lit source and then hesitate to leave it, and in doing so, become trapped in cities that offer little food for them. The birds then often crash into brilliantly-lit broadcast towers or buildings, or circle them until they drop from exhaustion. Finally, once on the ground, stunned or injured birds become vulnerable to predation. The pictures they have collected are stunning and gruesome.”
Photo by Gary Seloff of yellow-rumped warbler in breeding plumage at ABNC
From Houston Audubon:
“Most North American migratory birds fly at night, and lights on buildings can disorient birds on their paths, resulting in fatal collisions. The Upper Texas Coast plays a key role on the Central Flyway, an important migratory path for birds. Birds that move along and across the Gulf of Mexico depend on safe passage through the Houston-Galveston area. Throughout migration, and particularly during storm fronts, turning Lights Out for Birds can make a big difference. We encourage businesses, buildings, and individuals across the state to turn off all nonessential lights from 11 p.m. to 6 a.m. throughout spring and fall migration.” Through Houston Audubon, you may sign up for action alerts; these are sent out during times when large numbers of birds are moving through our area.
Go to https://alert.birdcast.info/lightsout/subscribe to subscribe!
These excellent guidelines have been suggested by Texan By Nature:
Do not use landscape lighting to light up trees or gardens where birds may be resting.
For essential lights (like security lighting) use the following dark skies friendly lighting practices:
o Aim lights down
o Use lighting shields to direct light downwards and to avoid light shining into the sky or
trees
o Use motion detectors and sensors so lights are only on when you need them
o Close blinds at night to reduce the amount of light being emitted from windows
The International Dark-Sky Association is dedicated to reducing light pollution around the world. Their site includes a step-by-step guide on how to save energy and lessen the affects of light pollution on our migrating birds.
Light pollution does more than disrupt bird migration. A study in Vienna showed that it affects songbird breeding behaviors:
Artificial night lighting advances the start of dawn singing in songbirds
Artificial night lighting increases male success at siring extra-pair young
Artificial night lighting advances the start of laying in female blue tits
Artificial night lighting may lead to unreliable quality-indicator traits
Join the cities of Houston and Galveston, and hundreds of other organizations across Texas, in pledging your support of this effort by turning off all nonessential lights during migration.
Thank you for protecting migratory birds by making these few simple changes!