Winter is prime time for watching bald eagles—here’s how Recovered from near extinction, the U.S. national bird is now abundant and easy to see. ByRene Ebersole Two bald eagles lock talons, tumble, and twist against a gray sky. Hidden inside a small wooden structure designed to allow people to spy on the birds, we crane our necks to watch their aerial acrobatics. Suddenly, one eagle breaks away and swoops low over the Mongaup Falls Reservoir in New York, startling a flock of black ducks that darts into the shallows. “It’s going to perch!” Brad Orey says, positioning a telescope and focusing the lens on a tree where the eagle has landed. “We’ve got a percher!”