An eastern screech owl banded as a chick, now established in its lifelong adult home, is always a special instructor. Such a recapture only happens once every few years, so its message is bound to be interesting. Suburban owlets disperse about a mile on average, so today's recovery of a three-year-old female in an exurban setting, five miles from suburbia, is special. My longest local record is nine miles, although a single remarkable one is ninety. The few (four percent) over three miles are almost all from suburbia into the surrounding countryside. Only one rural owl ever moved to town, which is quite different from the human trend.
When asked why one young screech owl in a thousand -- the number of nestlings I've banded -- traveled ninety miles when others stayed close to home, I answer that long-distance dispersal may only appear to be rare because the individuals are outside my search area and not easily found, or it could be truly rare, because few survive long trips through hostile territory. But such movement allows individuals to colonize new areas and perhaps spread novel genes into other populations, increasing variation that may increase survival as environments change.
Because suitable nesting habitat is patchy, our screech owls comprise semi-isolated breeding populations, and suburbia is a potentially important source of recruits for the rural environment. Many resources are better in town, so the city owls are denser and more successful nesters than their country cousins. This, together with less habitat, causes crowding, which stokes the suburban-to-rural supply line. In ecological terms, the suburban owls constitute a source population that may help to support a rural sink population, and that's a reversal of my expectation.
The human contrast is no surprise in view of suburban sprawl. Country folks shop in the city and move there in increasing numbers in response to increasing opportunity, which is why cities consume the countryside. A few wealthier folk reside in the country but make money in the city, so they aren't a true rural population. Certain urban birds, such as cattle egrets, grackles, and doves, use city roosts or nesting places and feed in cropland but most stay put, since travel costs can exceed food benefits. Because of their cultural resources, cities attract people in basically the same ways as they do the few native animals that can live there.