"Suicidal" starlings

[captivebolt]

It may well be the case that this question has long been answered, in which case I apologise for wasting time and space. I am raising it because I was struck by a comment in Richard Dawkins's The Greatest Show On Earth While discussing the ways in which complex behaviour can arise as a result of simple rules, he looks at the behaviour of flocking starlings. (Always sounds rude to me, those flocking starlings.)
Dawkins says that the flocks almost never collide, which is just as well, for given the speed at which they fly, any such impact would cause major injury. Could the explanation of the starlings flying into the deck be that some factor messed up their usual behaviour and caused flocks to collide?
I only ask because I'd like to know . . .

Captivebolt