Every year in spring and fall, billions of birds migrate through the United States. They take to the air to travel between their summer and winter homes. It’s a short trip for some. Others travel thousands of miles, sometimes flying for days without landing. People have known for a long time that some birds migrate. Over the years, scientists and researchers have used numerous techniques to learn which birds migrate and where they go.
Banding is the oldest form of tracking migrating birds. It is still used today. First, a bird is safely captured. Then, a small metal or plastic band is placed on one of its legs. Each band has a code that acts like a name tag to identify that bird. The bird is then released. If it is captured again later, the code can be used to learn where the bird has been seen before. One problem is that the chances of recapturing a banded bird are pretty small. Nevertheless, banding is still an important way to learn about bird migration.In the 1960s, technology using radio signals helped increase our understanding of migration. Scientists and researchers attach radio transmitters to captured birds. When a tagged bird is near a particular kind of antenna, the antenna picks up a signal from the tag. Radio tags were a big step forward, and they are still used. In the 1980s, there was another improvement. Satellites were used to pick up signals from tagged birds. There are different types of satellite systems, including the Global Positioning System (GPS) that we use to navigate in our cars.
Now, scientists and researchers have the Motus Wildlife Tracking system. (Motus is a Latin word that means “movement.”) The Motus system places radio antennas around the globe, which creates an extensive network for tracking bird migration. The towers are easy to set up and easy to move. The Motus system still uses tags, but the new tags are like tiny backpacks that can be attached to the smallest birds. They can even be used for migrating insects such as butterflies. The information on their tags is transmitted when they fly within a few miles of a Motus tower. Data from the towers is sent to a central computer.
A large group of science-based organizations has worked together to use the information from all of these different tracking technologies. They created an interactive tool called the Bird Migration Explorer. The Explorer can show animated maps of the migration journeys of more than 450 bird species. It uses migration records contributed by many researchers and organizations. The Bird Migration Explorer lets anyone see where tagged birds go throughout the year. It also shows the challenges those birds encounter as they migrate.
Migrating birds need healthy habitats wherever they are on their journeys. When migration patterns change, it means that something is happening that we should pay attention to. Science and technology are helping find answers and solutions. To find out more, check out the column on the right.
Photo: Camila Cerea