BirdNote

Birds chasing other birds is a natural part of the avian world. But when you add a skilled falconer, that pursuit can disperse pest birds from airports and amusement parks, and protect a farmer's fields.

The tiny Common Redpoll, one of the smallest members of the finch family, weighs only as much as four pennies, yet it survives the cold and darkness of winter in the far North. Most birds depart in autumn to warmer climes.

After breeding on Arctic cliffs and tundra hillsides in summer, Rough-legged Hawks winter throughout the Northern Hemisphere. Open country is their ideal territory, where the small rodents they depend on are usually so plentiful that the hawks have enough to eat.

Gerrit Vyn of the Cornell Lab of Ornithology recorded the Spoon-billed Sandpiper in the far northeast of Russia, where as few as 100 remaining pairs breed each summer. This sandpiper depends on key coastal wetlands near the Yellow Sea to fuel the long-distance migration to its wintering areas.

Project FeederWatch, sponsored by Cornell and National Audubon, is a window on the birds of winter. Through Project FeederWatch, scientists are able to track the movements of birds - including this Pine Siskin - and understand trends in population and distribution.

You may not have seen a Northern Cardinal in the wild, but you've probably seen one on holiday cards or the cover of a bird book. During spring breeding season, biologist Eric Lind and his team capture and band birds at Constitution Marsh on the east side of the Hudson River.

Trumpeter Swans land in a plowed field to forage for remnant potatoes, grain, and other waste crops. This swan is among the largest of all waterfowl; the Tundra Swan is somewhat smaller. These swans migrate in family groups each fall from nesting sites in Canada and Alaska.

Some early sailors, visiting remote Pacific islands, surely feared that the ungodly wailing on shore meant they had been tricked to the gates of Hell itself. In truth, they stood among courting pairs of seabirds called Wedge-tailed Shearwaters.

An owl's seeming ability to rotate its head in a complete circle is downright eerie. An owl's apparent head rotation is part illusion, part structural design. Because its eyes are fixed in their sockets, it must rotate its neck to look around.

When Hank Williams wrote Your Cheatin' Heart, birds probably weren't on his mind. But researchers have found evidence of what we might call "infidelity" in birds. Scientists in east Africa learned that female Superb Starlings often seem to have "cheatin'" on their minds.

Have you noticed groups of crows flying overhead in the late afternoon, wheeling and diving? These are American Crows with a purpose. They're headed to their night roost, a giant slumber party. Up to 40,000 crows in one space is not uncommon for a winter-time roost.

Riding the train west to New Haven or New York, you pass salt marshes with old and evocative names like The Saw Pit, Great Harbor, and Old Quarry. Watch for marsh birds - yellowlegs, sandpipers, Snowy Egrets. In the fall, you may find Northern Pintails, teal, and Black Ducks, like this one.

Some ducks don't sound like ducks at all. Some, like the Harlequin, squeak. Harlequins are unique in other ways, too. Quick and agile in rushing white water, they dive to the bottom of mountain streams for food, and use fast-flowing rivers for breeding.

Ravens are crafty! BirdNote listener Gary Cummins tells a story about the intelligence of ravens. When he worked at Grand Canyon National Park, Gary had a Siberian husky named Tasha. When two ravens saw her with a tasty bone, they teamed up on her.

Relatively few gull species are common nesters in the Lower 48. But in October, both the variety and number of gulls increase dramatically. Gulls that nested in Alaska or Canada fly south to spend winter in more temperate climates.