They go in on their own?Do your chickens swim Bob? I have a friend here in Phoenix with chickens and a pool and they go swimming when it’s hot out.
Mine have fallen in. I almost lost a young cockerel to hypothermia when it was 90°F and the water temp was in the 80s. It was quite scary.
Here is Ned swimming over to me to be rescued. You can see at the end that he can't walk due to the hypothermia.
Daisy, the greatest hen ever, provided me with this beautiful photo.