They roost in trees except while incubating and till the young can flutter in lower branches.
if they are still laying they will not return to a nest if it is destroyed or she is spooked off of it, she will renest somewhere else, if they are setting they will return. they have to hatch the clutch and raise them big enough to servive the winter, if they're nest is broken up while they are setting, they will not nest again as there isn't enough time to relay, incubate and raise the polts up big enough before winter sets in.
RR