The Canyon Wren's eloquent song soothes the soul. Naturalist Ralph Hoffman likened it to "the spray of a waterfall in sunshine." Its close cousin, the Marsh Wren, wound up with a harsh, ratcheting song - about as musical as a tiny machine-gun barrage. Birds' songs mirror their environments…

The Sky Lark is a bird whose songful brilliance inspired English poets, and gave its name to the phrase "an exaltation of larks." To glimpse a singing Sky Lark, look high up, where the male flutters and circles perhaps 100 feet off the ground, broadcasting its complex song. Around 1902…

For birds, a brain that can function while literally half-asleep is important to survival. In flocks of birds at roost, those at the outer edge of the flock often have one eye open. Such birds are truly half-asleep: one brain hemisphere snoozes as the other remains awake and alert. The eye…

In most birds - if the sexes vary at all in size - the male is larger. But with many hawks and falcons, the pattern is reversed. And female birds of prey are most notably bigger than males among hawk species that hunt agile prey, such as other birds. Perhaps the female Cooper's Hawk's…

In the Bahamas, in 1974, the Eurasian Collared-Dove escaped from captivity and began to breed in the wild. By the late 1970s, the doves had flown west and colonized southern Florida. As their numbers grew, the doves expanded into rural and suburban areas, moving quickly in a northwesterly…

In late September, young Great Horned Owls, now called "juveniles," still roost close together. By mid-October, the juveniles will scatter - or be driven away by the adults - to set up their own territories within a few dozen miles. By age two, they will seek their own mates. Learn about…

The largest known swift roost in the world - over 30,000 Vaux's Swifts - can be seen each September in Portland, Oregon, in a chimney at Chapman Elementary School. Portland Audubon hosts a Swift Watch. Learn more about this program and be sure to see a video of the swifts swirling down the…