I offer frozen water for the bird sto lay on in the afternoon, but with the fig tree, and dirt pit my dog digs, the birds manage to stay cool enough.
Birds who are bad for the heat will die off, and the ones who can handle it will survive and reproduce.
I'll bet all mine except Jace would die. Jace is a Texas birdie at heart.... It can be 87°F and muggy and she'll be running about, happy as a clam.
I know Emma would die.... She almost can't handle our summers...