It's quite common in August to think your birds have deserted you. Your feeders will likely be much quitter and even your trees and hedges will be pretty quiet and devoid of the normal signs of bird activity.
Don't panic, you may be concerned that your favourite characters such as the missing robin or blackbird have somehow succumbed to disease at the end of the breeding season or have lowered their guard enough to be picked off by the local sparrowhawk or cat. Usually these fears are unfounded and nothing sinister. Most times it is simply because the birds are not feeling up to much at this time of year; they are tired and lethargic because they are undergoing their annual moult.
Moulting, the changing of old feathers for new ones, is an important stage in a bird's annual cycle. Feathers are wonderful things, remarkably strong, extraordinarily light and easy to repair when ruffled but they are not indestructible.
They wear out, just as our clothes do, and must be replaced, which is the point of the annual moult.