The pigeon an urban success story

I'm kind of ambivalent about pigeons.

On the one hand, they're kind of funny. They've got tubby bodies and little heads. They'll waddle up to you for food, turn around in circles and applaud themselves with their wings when they take flight. On the other hand, they poop everywhere and never shut up.

I've spent many a winter with a flock of them perched above my study window, cooing and pooping incessantly as I cursed their name.

The rock pigeon (or rock dove) is one of Canada's most urban birds. Originally brought to Canada from Europe by French settlers as a food source in the 1600s, they've since spread across the continent, and can now be seen in most cities.

"Wherever people were present, the pigeon thrived," says Jocelyn Hudon, curator of ornithology at the Royal Alberta Museum.

A purebred rock pigeon will be blue-grey or blue-black with two black bars on its wings, says Roland Zacharias, a retired pigeon breeder who lives in Cardiff.

"Most of what we see in this country, up here in northern Canada, are rock doves mixed with some domestic birds," Zacharias says.

That gives wild pigeons tremendous diversity when it comes to their appearance. Most are blue-black, but some are grey, brown, black, white or any combination of those colours.

If you see a pigeon that's in the countryside with a long, pointy tail, it's probably a mourning dove, Hudon says. If your pigeon has a narrow dark crescent around the nape of its neck, you've got a Eurasian collared-dove.

Pigeons have no real way to defend their nests from predators, Zacharias says. In the country, they compensate by nesting on rocks and cliffs. In cities, they'll hide out under bridges, grain elevators and other structures – any place where they can put a roof between themselves and a hawk. They also prefer small, enclosed spots, as those are easier to warm when they huddle up in the winter.

Pigeon mysteries

Pigeons have been the subject of intense research over the decades due to their amazing navigational skills, which lets them find their way back home even when hauled hundreds of kilometres away.

Pigeons have some sort of internal compass to tell direction and a map to determine their location in order to do this, Hudon says.

While researchers are pretty sure the pigeon compass has something to do with the sun and the Earth's magnetic field, they're at a loss when it comes to the pigeon map. Past suggestions have included the Earth's magnetic field (problematic, as it would indicate latitude, but not longitude) and smell (controversial, as the birds would have to smell home from very far away).

One of the latest theories comes from Jonathan Hagstrum, a geophysicist with the U.S. Geological Survey who's studied pigeon navigation as a hobby for years. His research points to infrasound as the source of the map.

Infrasound is ultra-low frequency sound produced by the Earth and the oceans, Hagstrum says. It travels vast distances and can be heard by pigeons.

Hagstrum studied the work of renowned pigeon researcher William Keeton, who released hundreds of pigeons around New York as a part of navigation experiments. Keeton found that the birds almost always found their way home to Ithaca unless he released them from a particular spot near Jersey Hill. If he did, the birds almost always got lost.

"They would all depart in random directions as if they were getting no signals from the map," Hagstrum says.

Hagstrum discovered that, unlike all the other sites Keeton used, Jersey Hill was an infrasound dead zone – infrasound from Ithaca never reached it. The only time it did during Keeton's experiments was on Aug. 13, 1969 – the one day that Keeton's birds made it home from Jersey Hill without any problems.

Hagstrum says this suggests the birds use infrasound as their map. "They know what home sounds like, just as we know how home looks like."

He has yet to test his theory in the field, however.

Mess makers

Hudon says pigeons get a bad rap for pooping on statues and carrying the Newcastle virus, which can affect humans.

They also tend to get into buildings and make a mess, Zacharias says.

"Most of us (pigeon breeders) despise them as just being a kind of a nuisance."

But they're also a vital food source for many animals, he continues.

"They are the bottom of the food chain," he notes. "As soon as you wipe out the bottom of the food chain, you wipe out everything else."

I'm still not a huge fan of pigeons, but I must admit I'd miss these little coo-coo birds if they disappeared from my local bridge.