Wednesday, January 21, 2009

The birds in the background

kw: book reviews, nonfiction, natural history, birds

If you live in a city, you may often pass by a scene like this, but do you ever really see it? People who live in the suburbs are more likely to see, because the sight is not an everyday thing. But to a city dweller, the principal reaction to city pigeons is no reaction.

In Superdove: How the Pigeon Took Manhattan…and the World, Courtney Humphries traces the natural and human history that led to this situation. Once they were prime food birds, and in various "fancy" incarnations, they are still show birds. What has caused pigeons to be considered by many as "rats with feathers"? The pigeon population of urban Earth seems to be growing faster than the human population.

The author begins with Darwin—who raised pigeons while researching evolution—and ends in the beginning before that. In between, she traces the history of the domestic Rock Dove (now officially known as the Rock Pigeon) as it pretty much domesticated itself. What makes pigeons so well-adapted to living in human landscapes? Look at a city from a pigeon's point of view: they evolved living in cliffy areas, and our city buildings are big cliffs with plenty of nooks for nesting; they eat mainly grains, and we throw away or spill grain in copious amounts, particularly in and near cities (and many of us throw bread, a grain food, to them whenever possible); a city has relatively few predators; and many humans have an innate "white knight syndrome" that compels them to rescue hurt animals, including pigeons, and nurse them back to health.

Couple all that with a pigeon's territorial instinct, and a pigeon couple and all their offspring will, if sufficient food can be found, multiply to fill any cliffy urban landscape imaginable. They nest on the gargoyles and gingerbread of older architecture, on the struts and supports of air conditioners and signs, in the nooks that can be found even in modern and post-modern architecture, and any place that affords a flat spot an egg won't roll off plus a bit of shelter from the hawk flying above. They are opportunists, possibly second only to humans in that regard.

The pigeons we see in cities are not really wild, they are feral. They are descended from domestic pigeons: prior to the mid-1900s many houses had a dovecote to which the pigeons remained faithful. They were like chickens except that they fed themselves. They are also descended from escapees from the showroom. There are twice as many recognized breed of "fancy" pigeon as there are dog breeds.

The pigeon is a remarkably malleable animal. The color can be varied from the native gray-with-black-and-purple-accents color scheme to pure white, pure black, a whole range of brown and buff colors, plus blue-gray. The tail feathers can become a fan like a turkey's and the head and neck can become as decorative as a crowned crane. The head can sit atop a tall body, or pop out of the middle of a near-sphere.

All of this variety is the product of about three thousand years of artificial selection. Domestic dogs have been subject to artificial selection for five times as long, but pigeons have responded in an astonishing way by comparison. The size range of dogs trumps that of pigeons, but in all other ways, the variety of pigeons is without compare. All of these amazing breeds come from a smartly turned-out gray and black bird with some iridescence about the neck.

These city birds show the range of their parentage. The one at bottom center is the most similar to the wild Rock Dove. The rest just scratch the surface of the variation of city birds. Though these color and shape varieties are less extreme than their fancy kin, they are quite variable for a bird that can live on its own.

In her last chapter, the author narrates her quest to see truly wild Rock Doves (or Rock Pigeons). She was in for a surprise. They were hard to catch a glimpse of! In the "cliffs of home", wild pigeons have falcons and hawks to contend with. They are skittish and only take a flight longer than from one hole to another when they must travel to a field to forage for seeds or grain. Even the wildest pigeons take advantage of our grain fields, as do many other wild birds. So she did see them, one here, or two there, mostly for less than a second at a time. And this in an area that, her hosts assured her, housed several thousand birds. In a city, the feral birds would mostly be out in plain view. You'd see them all just with a casual glance around.

Throughout, the author makes the point that pigeons, even in cities, are part of nature. For some people, they are the only non-tame animals they'll ever see in any numbers. Feral pigeons live as they do because they can. They are very well suited to city life. Campaigns by various city authorities to eradicate them or reduce their numbers have all failed, with the exception of one scheme that partly succeeds: promoting a city-wide culture that "feeding pigeons hurts pigeons", to the point that most people no longer feed them. In a few Swiss cities where this has been diligently instituted, pigeon numbers have dropped by half or better. They're still able to get food, but this indicates that more than half of what city pigeons eat is provided deliberately by people.

We made the pigeon what it is. For some, pigeons may be pests; for others, near-pets; and for others they are just background noise. But they are the bird best suited to live where we live the most densely. They'll be with us for a long while yet.

No comments: