Definitely the main factor accompanied by dehydration. I tossed from 12 miles this morning at 6am & the birds were in the basket for no more than an hour, all home within 20 mins but diving for the drinker when trapping, so you can only imagine being dubbed up all night in the extreme heat we’re experiencing. Young bird racing needs to change probably to start in Late May with short races combined with old birds. If you do what you’ve always done! You know the rest!