Frank,
I,did my own survey on my own birds last year, which were extremely healthy throughout the pre-racing and racing season. The losses were heavier or returns patchy 3 days either side of the high solar flare activity which always seems to occur 1st or 2nd week in August. Hope your findings are successful, good luck Andy ;D
Ps:There was quite a high solar flare activity on Thu/Fri past. Any losses????