Soldier-based defences dynamically track resource availability and quality in ants

► We examined how soldier deployment in turtle ant colonies varies with the availability and quality of nest cavities. ► Soldiers were explosively deployed to new nest cavities, but older nest cavities retained a higher mean number of soldiers. ► High-quality new cavities were used more and were defended by more soldiers. ► Total deployment of soldiers to new cavities was constrained by overall soldier availability. ► Turtle ant defences are concordant with a general 'conservative bet-hedging' strategy.