What could bring crowds of people out after sunset on a September evening to stare at ... a chimney? Swifts, of course! Scores of swifts form a funnel-shaped cloud above the right kind of chimney, then they begin their descent. First one, then a few more, then dozens, then hundreds swirl…

Ranging from metallic hisses to electronic yodels, sounds of grackles may not be music to our ears—but they have their own rough beauty, a distinctive, primal harshness. Grackle songs evolved to carry through their nesting habitats — dense marshes and brushy landscapes — where more lyrical…

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. A field guide usually mentions these…

When birds like these Dunlin form flocks, each individual is less likely to be captured by a predator. Some shorebirds that forage with their heads down, like godwits, will flock with birds that forage with their heads up, like curlews. Still other birds work together — like American White…

Pigeons seem to bob their heads as they move, like they’re grooving to an internal tune. But what look like head bobs are actually momentary pauses of the head while they walk. Their eyes are fixed in their sockets, so that pausing enables the pigeon to take a brief, steady view of its…

Ospreys are remarkable nest builders. Many reuse their massive stick nests from the previous year, but continue tinkering with it once the nesting season begins. And the nest transforms along with the growing chicks. It’s bowl-shaped at first, corralling the young birds, but it gets…

Around this time of year, many baby birds are begging their parents for food. A Hairy Woodpecker chick calls from its nest carved deep within a dying tree. A Great Horned Owl juvenile reminds his parents "Hey! I'm over here! Feed me!" Moving from forest to water, we find this American Coot…

If you were to stand face to face with an owl, including this Great Gray Owl, it would eventually move its head, bobbing rhythmically from side to side, then forward, then back. Or almost completely upside down. This head-bobbing action helps make up for an anatomical limitation: an owl’s…

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…

There’s a group of birds that lay their eggs underground — in geothermally heated burrows, or warm sands, or even mounds of organic material warmed by the heat of decomposition. These megapodes or mound-builders — like this Australian Brushturkey — are found in Australia, New Guinea, and…