I know this is an IMAC Forum BUT:

At a Pattern contest in Andersonville Ga. Last year There must have been 6 or more birds mating in flight.
I swear it was like a episode of the twilight Zone. Then there was another 2 or 3 that had Radio Lock out or Wing Failure in flight.
I have been to combat contest that didn't have that kind of carnage.

Now an insight as to why. In pattern you have the BOX. Center pole And you have the 150 meter poles. Basicly telling the pilots to fly an area in a specific airspace. As the pilots skills of presenting better emprove there is more chance 2 planes flying the same line.

At least with IMAC NO defined box.

As Homer Simpson would say "Doh!"