Periodically a female V. rex will return to her nest site to urinate on the mound, the pungent scent being enough to ward off most marauders, though not all. The stealthy Adlapsusaurus seems immune to the dire warning given off by the urine. In fact it is drawn to the scent like a dinner bell and specializes in raiding nests, even those of a V. rex. Quick reflexes and keen hearing are the trademarks of the egg thief. It will make stealthy sorties to retrieve its prize before retreating to a hidden den to eat.
Adlapsusaurus also feed on small ground birds.