Laura Erickson's For the Birds

(Recording of a House Sparrow)

Last week when I parked at UMD to tape my program, half a dozen House Sparrows alighted on my car’s grill before I even shut the door, and started feasting on fried insects. All those poor roadside butterflies I’ve been hitting this summer have at least not been wasted. Most of the time the UMD House Sparrows seem to get their food from litter on the sidewalks, but if people are too neat, the sparrows aren’t above scavenging in garbage bins, too. They used to be common beggars at fast food joints in town, too, but have been pretty much edged out of there by the Ring-billed Gulls. These and several other species of birds have learned to find food and warmth in the castoffs of humans, and have developed many clever strategies for surviving in the urban habitat.

Nighthawks used to nest on cliffs and in burned areas of forests, where the stony ground camouflaged their eggs. But flat-topped roofs on buildings serve just as well for their nests, and so nighthawks quickly adapted to city life. They eat flying insects which are attracted by city lights, and so nighthawks benefit from city life in both their food and shelter.

Chimney Swifts don’t need human assistance to find their insects, but they do take advantage of human shelter. They used to nest exclusively in hollowed out tree trunks, but once they discovered chimneys and steeples they became far more abundant in cities than in the wild.

Although many species of birds cannot survive in an urban setting, the ones that learn to exploit humans can increase and multiply to become far more densely populated than the birds in just about any other habitat on earth. The urban habitat is not only rich in some kinds of food, it also affords protection from both natural and human predators. Many game species, from Mallards to Canada Geese, are safer from human hunters within city limits than they are in wilderness, so that now large numbers of these birds have ironically exchanged their wildness for protection against the species they now live with.

The invasion of a new species into an urban habitat is usually spontaneous, starting with a few individuals and eventually leading to the establishment of a permanent breeding population. The 60 European Starlings released in Central Park in New York City in 1890 multiplied like flies until they are now the most abundant bird in North America, a large proportion of which spend their entire lives in cities. Common pigeons originated from escaped birds which had been domesticated for racing, delivering messages, and providing food for man. The Ring-billed Gulls in Great Lakes cities arrived without human aid. The first pair of gulls to breed in the Duluth harbor was noted in 1974, and from that small beginning the current colony of 20,000 birds arose. All in all, the total density of birds in cities can be over three times that in forests, and well over 10 times greater than in grasslands or deserts. And single species in cities often are hundreds of times more concentrated than the same species in wilder reaches.

People who live in cities don’t often pay much attention to the birds around them, but in my mind birds add a necessary dimension to city life. Downtown Duluth would be dull indeed without the cheeping of House Sparrows, the chittering of swifts, the buzz of the nighthawk, the joyful winging of pigeons, and the ubquitous gulls gleaming white as they sail against blue sky and brick.

(Recording of a Ring-billed Gull)

This is Laura Erickson, and this program has been “For the Birds.”