After the spring migration and tear and wear during spring and summer, the feathers of the adult lessers are in a bad shape. Before they can migrate south they need to change the old feathers with new ones. The moulting period is a critical time since they loose the ability to fly for a month's time. In this period they stay close to the edge of the lake. At the first sign of danger they will disappear out on the water where they are safe from predators.
The goslings will also change from the downy plumage to a fully feathered one. The timing is synchronized with the parent's so that they all regain flight ability at the same simultaneously.
