Who knew?

The Kiwi, the only wingless bird

A few thoughts about birds, bird behavior and the language of birds …

When a group of hawks rides a thermal, the birds seem to swirl upward like the steam rising from a boiling kettle. That's why a group of hawks is called a "kettle."

In winter, the Ptarmigan in Alaska grows special feathers on the tops and bottoms of its feet. These work like snowshoes, allowing the bird to walk across the surface of the snow.

Many birds line nests with feathers to help warm the eggs. It is from this practice that we get the phrase "to feather one's nest," which means to stock up on goodies for oneself, often at someone else's expense.

The natives of New Hebrides, a small group of western Pacific islands, used feathers for money. One honeyeater feather was worth one pig or two wives.

Overheated birds don't sweat but some pant. Herons, for example, rapidly vibrate their throats to increase evaporation. Ornithologists call this gular fluttering.

Although there are 46 species of flightless birds, the Kiwi of New Zealand is the only wingless bird.

Migrating ducks and geese often fly in V-shaped formations. Each bird flies in the upwash of its neighbor's beating wings. This enables the bird to fly 70 percent farther than on its own.

Flamingoes strain food out of their water through horny plates inside their beaks. The Lesser Flamingo has a filter that can trap single cells.

Birds have enormous eyes. Our eyes make up less than 1 percent of the weight of our head. Owls have the biggest eyes relative to the size of their heads. If we were an owl, our eyes would weigh several pounds.

Greek legend says that just before the Mute Swan dies, it bursts into a beautiful song. Today, any artist's last work is called the "swan song."

Birds sing or squawk with a syrinx, stretchy membranes located at the bottom of the windpipe. Birds can sing with their mouths full; they also can sing two different notes at the same time. The two sides of syrinx use air from a different lung.