Someone asked me the other day what my favorite bird is. Today it's pigeons.

I love the way flocks of pigeons fly. They swoop and glide, pump up speed, then float. They circle, they soar. Pigeons display the pure joy of flying. They fly like they're having fun.

There's a small flock of pigeons living in a parking garage in downtown Wayzata, behind the Caribou Coffee shop. Now and then I'll see them airborne, circling. They fly hard, wings strumming, speed building. They're reminiscent of a playground merry-go-round, pushed as fast as you can run, ridden with wind in your hair.

Pigeons don't migrate. They're loyal to their neighborhoods. The Wayzata birds come out now and then, fly in circles, returning to whatever pigeons do to kill time.

Pigeons like urban parks. Being granivorous — eating grains and seeds — pigeons like farms with silos. They like grain elevators. They like large, open public spaces, like St. Peter's Square in Rome or Loring Park, where people feed them. Pigeons forage for food, but can live on handouts.

Pigeons can be found near highway bridges because their understructures often have flat surfaces that attract nesting and loafing birds. The birds, introduced to North America 400 years ago, are cliff dwellers in the wild. Bridges and window ledges on downtown buildings are wonderful cliff substitutes.

(If you have pigeons loitering at your house, perhaps to your annoyance, there is a simple way to get rid of them. They build flimsy nests so they avoid slanting surfaces because eggs roll. Create pitch where the birds roost or nest.)

The good with the bad

Pigeons are beautiful but dirty birds. Not dirty like muddy, but dirty like droppings.

Wild pigeons commonly are various shades of blue and gray. Pigeons are kept as pets, bred to many colors, shapes and behaviors. Wild pigeons that aren't gray most likely are escaped birds or their descendants. You can find them white and rust, in many shades and blends.

Pigeons' feathers, particularly around the neck, are iridescent. Pigeon eyes can be strikingly beautiful.

On the other hand, one pigeon in one year can produce 25 pounds of droppings. Technically, this is guano. Colloquially, it has other names.

Technically, the bird you are reading about is not just a pigeon. It's a rock pigeon, so called because of its original nesting preferences. It's one of four common North American pigeons, part of a family that includes 13 species of doves. The pigeons are rock, white-crowned, red-billed and band-tailed. The three latter species are found in either the Southeast or Southwest.

There was a sixth species, the passenger pigeon, existing in billions, extinguished by us, every single bird.

Fodder for study

Pigeons are among the most intensely studied of all birds. They're easy to find, easy to raise, smart and amenable to research.

Among the subjects to which pigeons have contributed are flight mechanics, thermoregulation, water metabolism, endocrinology, sensory perception, orientation and navigation, learning, genetics of color, pattern and behavior, and Darwinian evolutionary biology.

The scientific literature stemming from these and other studies is enormous.

Pigeons are about a foot in length, with a two-foot wingspan. They weigh about as much as a $30 steak.

There are an estimated 400 million pigeons worldwide. No guano, that's a lot of pigeons.

Read Jim Williams' birding blog at startribune.com/wingnut.