Almost every year a sharp-shinned or Cooper's hawk stays for the winter and eats mostly the abundant and na´ve offspring of permanent resident birds. The hawks quickly learn that such food is concentrated at bird feeders and seem to visit several in rotation, like humans on shopping trips. I know one female sharpy personally, a bad biter if I catch her to check her band. I don't always see her right away, but I know when she arrives because blue jays suddenly become quiet, in contrast to loudly pestering the migrant crows that also move into our neighborhood grocery.
Eastern screech owls begin to eat more birds, as insects and reptiles become less active on cooler nights, but are not pressured by the arriving hawks, since avian prey is two to three times more abundant here than in the countryside. Of twenty-two common songbirds in ravine and rural habitats, thirteen are more common and their populations more stable, year-to-year, in suburbia. These include such favored lunches as northern cardinal, blue jay, house finch, house sparrow, and northern mockingbird among permanent residents, and American goldfinch, yellow-rumped warbler, white-throated sparrow, and dark-eyed junco among winter residents.
My censuses show that permanent residents have increased, while winter residents cycle with the severity of the winter (more in harsh weather). The raptors have no long-term influence on their numbers. Seventy-five years ago a study of the avian prey of eastern screech owls in New York found the same thing; so the message, like the Biosphere's other fundamentals, is time honored. Why would any predator destroy its livelihood and thus itself? The problem here is a decline in summer residents (neotropical migrants), also unrelated to raptor numbers, but to numbers of the only predator that reduces or exterminates unintended prey by damaging or erasing wildlands.