By Ryan Call, Houston Audubon 2021 Young Professionals Advisory Council (YPAC)
About this time every summer, we receive questions about ridiculous-looking birds: birds with oddly mismatched feathers, birds without feathers, birds that seem bedraggled or undernourished or sickly-looking. For the most part, these birds are perfectly fine! They’re just in the midst of a completely natural process that keeps them flightworthy and healthy and ready for the next phase of their lives. Just as it’s important to understand fledging and why we should usually leave young birds alone in the spring and early summer, so too is it important to understand how and why birds’ appearances often change towards the end of the summer.
The simple answer is this: birds molt—that is, they lose feathers and replace feathers.
Of course, molts are as complicated as birds! Some birds, like ducks and loons, molt completely, while other birds molt partially. According to National Audubon, a raven’s molt can last up to six months, and soaring birds, like vultures, will replace their flight feathers in a staggered manner so they can stay in the air! Some birds take a year to reach their adult plumage while others, like gulls and eagles, go through several years of juvenile plumages before reaching their adult form.
Usually, the molt people most often ask about concerns the change in appearance of a relatively common adult backyard bird transitioning from breeding to basic plumage, taking on their non-breeding appearance for most of the year before the next breeding season. This is because birds often have an alternate plumage that helps them attract mates and breed, and once the bird has fulfilled this purpose, it no longer needs that plumage.
Growing new feathers takes up lots of energy, so late summer is ideal for many birds to complete their molt and get ready for winter. This is because they are done with the energetically expensive breeding season and have yet to reach the energetically expensive fall migration season.
So, next time you see a completely ‘bald’ male Northern Cardinal, know that it’s probably a-okay as it waits for a new set of feathers to grow!