I have offered every bird here a sizable cash bonus plus central air conditioning to be installed in their coop IF ONLY they would eat up the fire ants on our property. So far, neither the chickens, guineas, ducks or geese have taken me up on this offer.
I use a few gallons of boiling water, poured from up high in order to have a forceful stream (wear high rubber boots, watch your legs!).
Sevin Dust is also effective, sprinkled over & around the mound. That doesn't bother the birds either.
I wonder if there is more than one type of fire ant, that some are more appealing to chickens, some are more easily eradicated by Sevin Dust.