Help solve this mystery - what killed two of my neighbor's hens?

[Feathered Wings]

The heat is brutal here in georgia in the summer we can get well over a 100.
I have a sprinkler set up so it covers all my pens i turn it on in the heat of the day.
I will cool them down turn it off and then turn it on periodically.
This method i'm sure has saved the lives of my chickens and other animals.
All my coops and pens are completely shaded by trees and i still lost a rabbit 2 years ago. (lesson learned the hard way)

Sending good heart felt wishes your way