Each spring, billions of birds
fly vast distances to spend the summer in North America, most of them traveling
at night. It's a trip fraught with peril: Many slam into wind turbines or
brightly lit buildings. Now, a new forecasting system for bird migration could
help put an end to millions of those deaths by warning wind farm operators and
building managers of incoming migrations 3 days in advance.
Although hawks and other large
species migrate during the day, most small birds migrate at night to avoid
predators and enjoy better flying conditions. The daily legs of these
migrations depend heavily on the weather. If conditions are too cold or rainy,
migrants hang out in trees until the skies clear. And birds are more likely to
continue their journeys when warm air signals an incoming, southerly tailwind.
Since 2012, the Cornell Lab of Ornithology has made predictions about these
migrations by using observer sightings and regional weather reports on its
BirdCast website.
To scale up and automate these
forecasts Benjamin Van Doren, a Ph.D. student at the University of
Oxford in the United Kingdom, and Kyle Horton, a postdoc at the
Cornell lab, built a computer model of weather and bird migration. They began
with weather radar, the only effective way to monitor night-time migrations.
Individual birds can't be detected, but radar can reveal the density of birds
in the airspace: 60 to 70 birds per cubic kilometer in a light migration, and
as many as 1700 in a heavy one.
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