This is a trick question. Where would you expect to find the greatest variety of birds? Downtown, in a city? Or far, far from downtown — in the fields, forests, mountains, where people are scarce? Or in the suburbs? In backyards, lawns, parking lots and playing fields? Not the city, right? "Everything I have learned as a conservation biologist tells me cities are bad for biodiversity," writes John Marzluff, of the University of Washington. We all know this. Anyone who goes to downtown Chicago, Toronto, Seattle, LA, Boston or New York will see the same five birds over and over: sparrows, starlings, mallards (ducks), geese and, of course, street pigeons. Same goes for downtowns in Europe, Asia and South America. These five bird types are always there, always the same, never surprising. Rather than yawn, scientists have a category for this: "biotically homogenous." We've made cities. They've moved in. A Seattle Experiment But now comes a surprise. Actually, several surprises. When
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