Seagulls use a technique called "worm grunting" to find food, where they stomp on the ground with both feet rapidly to attract earthworms to the surface. The vibrations from the stomping mimic the sounds of heavy rain or moles tunneling underground, causing worms to emerge from the soil. Once worms appear, the seagull quickly catches them in its beak. Though it's unclear exactly how seagulls first developed this behavior, it has likely spread through their social learning and observation of other seagulls.