It’s spring, and a female duck swims across a pond with ducklings in tow. Some of the youngsters might not be her own. Wood Ducks and others may lay some of their eggs in other ducks’ nests — or in the nests of other kinds of ducks, like Common Mergansers and goldeneyes. Biologists call…

Elegant Black Terns breed in summer on secluded wetlands across the northern states and Canada. Because of major losses of wetlands in their breeding range — especially in Canada's prairie provinces — Black Tern numbers have dropped dramatically since the 1960s. The future of this…

Two eagles locking talons high above the ground might look like they’re risking injury, but it’s a normal courtship behavior called the “cartwheel display.” Fully entangled, the two birds begin spinning to the earth, disengaging just before they smack the ground. Their clasp could last for…

Noticeably smaller than Mallards, Blue-winged Teal wings have large patches of powder blue edged in emerald. Blue-winged Teal are long-distance migrants, traveling from nesting areas in Canada and the U.S. to South America for the winter. They feed in shallow water with a preference for…

Peer into the world of birds, and eyes of many different colors peer back. While eye color isn’t tied to one group of birds or another, a common pattern is a change in eye color as immature birds grow to adulthood. Bald Eagles, Ring-billed Gulls, and ducks such as goldeneyes and scaup have…

Tree Swallows glisten in the June sunlight, as they swoop and glide, their arcs interlacing in the air. When a white feather flutters down among them, one swallow snatches the feather in its bill and flies upward, as another gives chase. After a moment, the lead bird lets loose the feather…

When nesting, most birds lay a predictable number of eggs. Bald Eagles: 2. Bluebirds: 4 to 6. Mallards: 10 to 12. But how do they determine when they have laid the right number? To find out, scientists experimented by going to nests and repeatedly removing eggs soon after they were laid…

What’s the most colorful bird in the U.S.? The Scarlet Tanager? Maybe the Painted Bunting? Well, consider one more lustrous candidate: the Purple Gallinule. The Purple Gallinule’s feathers are so iridescent that they might not seem real. Despite its bold style, a Purple Gallinule can be…

During the days of mammoths and saber-toothed cats, California Condors thrived over much of the continent. Today, they're one of the most endangered birds in the US. The condor's main survival problem is high mortality due to lead poisoning. Condors eat animal carcasses, often containing…

Summer is a crucial time to keep your backyard birds supplied with water for drinking and bathing. Birdbaths set at different heights serve a great variety of birds. A wide, shallow birdbath that deepens a bit in the center will suit a broad range of birds - including this American Robin…