Monitoring Night Migration
Twice each year, millions of birds migrate across the Americas to and
from their breeding and wintering grounds. Although many species are
invisible in the dark as they fly overhead at night, they often
vocalize as
they travel. On a busy migration night in eastern North America,
listeners on the ground may hear thousands of calls.
 Bill Evans looks at a computer-generated sonogram of a night-migrating songbird. |
By using autonomous recording
units to record these sounds from rooftop microphones, researchers at
the Cornell Lab of Ornithology can access a rich source of information
about these little-known migrations. With the aid of specially designed
software, researchers can quickly identify which bird species, and how
many, were calling on any given night. Ultimately, a network of
listening stations could help document the magnitude of migration
across the continent and from one year to the next.
For more information
How Many Birds are Migrating in the Dark? Researchers tune into nocturnal flight calls. BirdScope, Autumn 2006.
Night Sounds: Tracking the nighttime movements of migrating birds. BirdScope, Summer 1994.