Fun Facts about Bird Migration
Bird Migration—Year of the Bird
While birds have been migrating forever, sometimes over very long distances, we are just beginning to understand these migratory pathways. Birds migrate from an area where lack of food threatens their survival to an area where food is more plentiful. For thousands of years, the “disappearance” of birds for periods during the year was a source of mystery, wonder, and even myths. Today, with the help of banding, and even satellite transmitters inside the bird’s air sac, we can follow their migrations and learn about their behavior and habits.
Here are some interesting facts about migration:
· How do birds prepare for migration? Many birds increase fat and muscle tissue. Tiny hummingbirds double is size. Some long-distance migrators shrink organs that will not be used for the migration as they bulk up other tissues.
· How do birds know what migratory pathway to take? They use a variety of navigational cues, including familiar landmarks, the sun and stars, and even the earth’s magnetic field. Use of magnetic fields helps particularly those migrating to the poles, where magnetic fields are strongest; some birds have sensors in their eyes that detect the magnetic field.
· Some birds migrate non-stop over long periods; how do they do this without sleeping? Birds use wind currents to help them rest during long trips. Some birds take brief naps while soaring. Other birds are able to put half their brain to sleep while the other half stays awake.
· What hazards do birds encounter while migrating? Some stopover sites such as the Yellow Sea in China are being destroyed to build ports, factories, and housing. Land in migratory pathways is being cleared of vegetation to make room for agriculture.
· What is the longest nonstop migratory flight ever recorded? Over eight days and nights a Bar-tailed godwit was followed from Alaska, past Hawaii and Fiji, to New Zealand, a trip of 7,150 miles.
· What is the greatest bottleneck for birds migrating to and from South America? Panama. Imagine, the US and Canada are approximately 2500 miles wide; and most of the birds who make this migration funneling through 60 miles of tropical forest in Panama. Do you think birds get “road rage?”
· We hear about threats to migrating birds caused by with various manmade structures. According to S. R. Ross (Direct human-caused mortality of birds (2012), Annual Review of Ecology, Evolution, and Systematics), below are the major threats and the estimate annual mortality caused by them:
o Residences: 253 million
o Power lines: 22.8 million
o Wind turbines: 366,000
o Communication towers: 6.6 million
o Buildings: 340 million
That’s a lot of birds! Let’s do all we can to protect them, starting with windows in our homes.
Other sources: Hugh Powell (Autumn, 2018), The Habitat Up There, Living Bird. National Geographic (March, 2018), Epic Migrations.