Fire ants may be resistant against water, but ya, boiling water can kill a lot. Here is the problem though, you will need a lot of water to kill their queen. Fire ants place their queens deep underground, deep enough that rainwater doesn't bother them, and to get rid of a colony, you must get rid of the queen. Also, I agree with the avoidance of using chems, I just wanted to tell you a possibility.

-ps, I bet your elate seasons are painful, literally. But the good thing about chickens is that they eat everything, but, just like a pet lizard, do not give them to much live food or else they become the food. Keep your chickens away from the ant nest and they can have a little snack, or they will learn to avoid them.