When they reach sexual maturity, from four years old, the yellow-legged gulls (Larus michahellis) have red spots appearing on their lower mandibles. As soon as they are hatched, the newly-born chicks instinctively peck those of their parents to induce the regurgitation of food in their throats. Yellow-legged gulls are numerous around the banks of the artificial lake of Serre-Ponçon, created in 1959 in the Hautes-Alpes department.