About Tracking Bird Migration
By exploring the ways we track bird mi-
gration, from geolocators and banding to
feather analysis and surveys, we can also
examine the threats birds face in their
migratory journeys and highlight the com-
munities on the ground that are working
to support them. Through WMBD, we can
all take action to protect our shared birds
and their habitats!
For centuries, birdwatchers contemplated why
so many birds disappeared from their homes
but are seen in other geographical areas. Be-
cause birds acquired very different plumages
and gained a lot of weight, the ﬁrst naturalists
thought that the birds had not disappeared
but were transformed into other species. The
Greeks thought birds turned into ﬁsh over the
winter because they saw all birds ﬂying towards
the open ocean. We tackle the 2020 WMBD
theme, sharing what is we know about the
history of bird migration, the tools and methods
involved to inform us of their journeys and des-
tinations, theoretical and evolutionary hypothe-
ses, and the major contributors in this exciting
ﬁeld of ornithology.
Today, scientists use a variety of technologies
to explore the migration routes of many birds as
they move across different spatial and temporal
scales, either as part of their daily lives or as
part of seasonal migration. Along the way, birds
seek resources in different environments. At
the same time, they face natural disasters and
human-related risks on the ground and in the
skies. We know a lot more today than we did
long ago; however, a complete understanding of
how these precise navigational journeys work is
still a big challenge!
Example tracking methods that researchers
use to learn about bird migration.
BIRD BANDING: Bird researchers use metal bands, each with a unique code,
to identify individual birds. Each time a banded bird is captured, we learn more
about its age, health, and habitat use. Support and visit a local banding station
with ethical and scientiﬁc approaches to capturing and banding wild birds.
RADIO TELEMETRY: Radio telemetry uses electromagnetic radio waves to
determine a bird’s location. A transmitter is attached to a bird’s back, and an
antenna captures a radio signal. The receiver then transforms that signal into a
beeping sound that gets louder the closer it is to the transmitter. The signal indi-
cates that the bird is near. Automated radio telemetry systems have increased
the scale of detection without having to rely on individuals being recaptured.
WEATHER RADAR: We use weather radar every day to detect the movement of
drops of rain. It can also indicate the location of moving birds. Watch a tutorial
video for viewing nocturnal bird migration using radar on The National Center for
Atmospheric Research website: vimeo.com/2020985
LIGHT-LEVEL GEOLOCATORS: These tracking devices use daylight to estimate
location. From sunrise/sunset data, the relative time of noon and midnight is
determined to assess the geographic coordinates of migrant birds. However,
in the shade of a tree canopy, it can be difﬁcult to determine what the sunrise
and sunset times are. Because they are lightweight and have a long battery life,
light-level geolocators are an excellent option for studying long distance
movements. Explore the sunrise and sunset times where you live and around
the world: esrl.noaa.gov/gmd/grad/solcalc
SATELLITE TAGS: Satellite tags attached to birds send signals to the satellites
that orbit the Earth and provide the accurate location of the bird. Researchers
only need to capture the bird once to afﬁx the tag. There are 31 GPS satellites in
orbit that provide highly accurate location data. You use this data daily on your
smartphone to navigate to a restaurant and check trafﬁc at rush hour.
CITIZEN SCIENCE: by sharing their observations, everyone can be part of our
efforts to learn about bird migration. Here are a few you can join:
• iNaturalist inaturalist.org Share your observations with other naturalists
and discuss your ﬁndings.
• Journey North journeynorth.org Track Hummingbirds are too small to carry tags,
so your observations are an important part of our understanding of their migration.
• Hummingbird Highway westernhummingbird.org/hummingbird-highway Share your
research, pollinator garden, and hummingbird-focused education activities on a map,
so that we can make connections to hummingbird conservation.
• eBird ebird.org Your bird sightings contribute to our awareness of migration across
the globe, plus you can keep a list of every bird you see and where you’ve seen it!
e incredible phenomenon of bird migration has always been an enticing topic among the world’s
ornithologists, as well as the general public. Birds fascinate and impress people of all ages because of their
extraordinary journeys. Although bird migration is a worldwide phenomenon, many people do not know how
scientists learn about birds’ routes and destinations, or how they use this knowledge to inform conservation.