Birds rely on their feathers for flight navigation, temperature regulation and for general protection from the outside world. Even with regular bathing and preening, feather-wear happens. Eventually new feathers must be grown to replace worn feathers. Most birds will grow a complete set of feathers at least once a year. It takes a lot of energy to grow new feathers, so this is typically done late in summer when other energy costs are low. This process is called “molting” and for most birds it is both gradual and symmetrical.
Molting of body feathers leaves a bird looking pretty rough which, to the untrained eye, can appear as if the bird is suffering from an illness or injury, rather than the result of a natural and healthy process. However, missing or having partially grown-in wing and tail feathers affects a bird’s ability to fly and navigate. This makes it more vulnerable to predation if detected. With nesting season coming to an end, birds are singing less. With molting underway, birds will spend more time in places that offer cover to avoid being noticed by predators. As a result, birds can go undetected and we start to feel like our yard is bird less in late summer, when really it is not.
Make time to sit quietly and watch for birds darting about in your yard and see if you can tell what feathers are being replaced at any given time.