Raptors are diurnal migrants - night time will bring them down.
I suspect the need/desire to feed will also bring raptors into places where they can re-stock for the ongoing journey - hence the good numbers of Amur Falcons over the wildfowl collection at Mai Po las autumn.
It has been thought for a few years that Amur Falcons go through high and it seems likely that in good conditions many other raprtors do too - not many people have the patience to stare into an empty sky!
I agree wth goeff that there is little in the way of adverse weather in october, so its unlikely that birds will be grounded by rain or cloud.
Cheers
Mike K
