Geography Reference
In-Depth Information
in part using vision. This sense is compromised by the presence of red or
white lights, which often adorn a city's highest towers and antennas. Other
birds, reluctant to leave the lighted area, circle until exhausted. Some die in
the predatory grip of night specialists, such as owls. Hundreds of dead and
injured birds can be found in major cities every morning at the base of lighted
skyscrapers. Experts estimate that nearly seven hundred thousand die annu-
ally from skyscraper collisions each year in the United States and Canada
alone. Upwards of seven million may die each year in the United States and
Canada when they strike towers. Warblers, especially the black-and-white,
worm-eating, golden-winged, Canada, and Kentucky varieties, are frequent
casualties because they migrate at night.
Some city light is needed for public safety and ei cient commerce, but
much is emitted needlessly in ostentatious displays that erode the quality of the
habitats created in our yards, parks, and recreational spaces. In terms of the
number of birds killed, excessive lighting can undo our best ef orts to diversify
land cover, keep cats indoors, and increase the visibility of our windows.
Reducing the harmful ef ects of luxury lighting is something that everyone
can do to improve our built environment's ability to support birds and other
animals, whether you live in a small l at or are entrusted to plan the growth of
a major city.
Three simple concepts can greatly reduce the harmful ef ects of light.
First, use light only when necessary and then from as dim a source as pos-
sible. Bright bluish light is the most disruptive, and softer yellowish light is
least disruptive. Second, where warning lights are necessary, the use of
blinking rather than steady emissions and blue or green rather than red or
white lights reduces collisions. Regulatory agencies in the United States rec-
ognize the benei t of blinking lights and allow many tower operators to turn
of steady red lights and replace them with fewer, blinking ones. This mea-
sure costs little and pays operators huge dividends by reducing power bills
in addition to saving birds. Third, face outside lighting downward, not sky-
