Late summer is the time of year when many birds replace their feathers in a process called molt. Old feathers, most of which have been worn for about a year, fall out, and new feathers grow in their place. Gulls, for example, molt their wing feathers only once a year, and we generally don’t notice any change in their appearance. The color and pattern of their wings remain the same all year. After a year of constant wear and exposure, it’s amazing that feathers still function, let alone retain essentially the same appearance.
If you are at the beach at this time of year, you will probably find feathers on the sand. Virtually all of these will be old feathers, “used” by the birds for up to 12 months and then dropped in the normal process of molt. Among them you might find large wing feathers dropped by gulls. It’s illegal to keep these feathers, but you can pick them up and examine them.