 It has a first spawning period in early summer, and a second one in the fall.Lifespan is typically five to six years, though it may perish earlier due to predation by humans as well as crabs, flounder, and various birds especially including oystercatchers.A green shore crab ("Carcinus maenas") can consume up to 40 common cockles a day, eating smaller cockles (under 1.5 cm diameter) much more quickly than larger ones.