A few facts about migrating birds from the Audubon Society and the World Wildlife Federation:The tiny ruby-throated hummingbird weighs less than a quarter of an ounce but can fly 500 miles nonstop across the Gulf of Mexico.
Bar-headed geese fly higher than any other birds, crossing the Himalayas at nearly 30,000 feet on their journey from central Asia to their wintering grounds in the Indus Valley.
Snow geese fly at an average speed of 50 miles per hour. They travel roughly 3,000 miles each year, flying at an altitude of 2,950 feet. The geese have a 35-inch wingspan.
No creature on Earth migrates farther than the Arctic tern, which can cover more than 18,000 miles in its annual journey from Arctic Canada or Siberia to Antarctica and back again. This bird, which weighs less than half a pound, probably sees more sunshine each year than any other creature on Earth.
The sandhill crane flies an average of 2,500 miles each year. The barn swallow may travel more than 6,000 miles. The American robin, on the other hand, may travel only 100 miles from summer to winter home.
Black-poll warblers often fly for 3 1/2 days -- 84 hours -- without stopping.
Wetlands -- marshes, swamps, bogs and similar areas -- provide rest stops for migrating birds. About 80 percent of all bird species in the world inhabit wetlands.