Backyard Visitor

Yesterday morning this bird of prey was scanning my back yard from atop my daughter's practice net for lacrosse. The bird is about 10" long not including its tail. The photo was taken from inside my house at a distance of about 30 feet. Does anyone know what kind of bird this is?

Thanks to everyone who suggested identifications. I now think that it is probably an immature (because of the yellow eye) Cooper's Hawk. A detailed description of its breeding behavior is available here. It preys on small birds and rodents, which are plentiful in the neighborhood. Hopefully there will be another sighting to check for the expected bands on its tail.