BirdNote

It's spring! And for many birds, a time to look their best to attract a new mate. This American Goldfinch has recently molted. Its old, worn-down feathers have fallen out, and new ones have grown in. When goldfinches molt in the fall, they lose these brightly colored feathers.

It's April, and godwits are on their way north. They have wintered along the coasts, including the Texas Gulf Coast, and along the Pacific from California to Washington. While most breed in the prairie provinces of Canada, some nest as far north as Alaska's Aleutian Islands.

Most birds possess the ability to see color. But birds can also see in the ultraviolet spectrum. Hummingbirds - like this Violet-crowned Hummingbird - may zero in on certain flowers because their petals strongly reflect in the ultraviolet range.

Which Chickadee - Black-capped or Carolina?

This Scarlet Tanager (R), its cousin the Western Tanager (L), and your latte have a connection. Much of the birds' prime wintering habitat has been turned into coffee plantations.

Two herons, one dark, the other white, feed at the edge of a wooded pond in the South. Both birds are Little Blue Herons. What's going on here? Well, the white bird is a juvenile. These young herons forage with flocks of Snowy Egrets, which stir up prey.

To distinguish one bird from a similar one, watch how the bird moves. Does it flick its wings? Bob up and down? Flip its tail? The White-breasted Nuthatch (right) works its way down the trunk of a tree, while the Brown Creeper works its way up.

All states have an official bird, usually one that's associated with its particular region. Many state birds are quite common, although Hawaii's chosen bird, the Nene, a type of goose, is endangered.

Voices and Vocabularies - The Basics

Red-bellied Woodpeckers are bold, conspicuous, and vocal, thriving in rural and urban areas east of the Mississippi. Like most woodpeckers, Red-bellieds eat lots of insects. But they also like nuts, berries, and seeds.

The mortality rate is high in our familiar songbirds. For robins, it's around 50% each year once young birds have fledged. If a robin survives to midwinter, it lives an average of 1.7 years after that.

Why do birds sing? Ornithologists have learned that the longer hours of light that come with spring trigger the release of hormones in birds. These hormones prompt the enlargement of the birds' gonads which, in turn, stimulate male birds to sing.

Gordon Hempton, the Sound Tracker, records the sounds of nature in pristine places. Mesmerized by a Winter Wren singing in the Joyce Kilmer Memorial Forest of the Carolinas, Gordon chased the bird up and down a mountain before capturing its song at close range.

While nearly a third of North American bird species are in decline, many birds that depend on wetlands are thriving. Duck breeding populations in 2009 were an estimated 25% above historical averages.

Visit a shallow wetland in summer, and you might see this slender, black-and-white shorebird with outrageous red legs.