The Eurasian Crag Martin feeds mainly on insects caught in its beak in flight, although it will occasionally take prey items off rocks, the ground, or a water surface. When breeding, birds often fly back and forth near to a rock face hunting for insects, feeding both inside and outside the nesting territory. At other times, they may hunt flying above streams or alpine meadows. The insects taken depend on what is locally available and may include flies, ants, aerial spiders, and beetles. Aquatic species such as stoneflies, caddisflies and pond skaters appear to be important in at least Spain and Italy. Unlike other hirundines, these birds feed close to their breeding sites, and may be locally vulnerable to fluctuations in insect availability. This martin is gregarious outside the breeding season, and may form sizeable flocks where food is abundant. Cliff faces generate standing waves in the airflow which concentrate insects near vertical areas. The Crag Martin exploits the area close to the cliff when it hunts, relying on its high manoeuvrability and ability to perform tight turns.