If you’ve visited the sanctuary recently you may have noticed lots of feathers on the ground. This is because the birds are molting. Once or twice every year, birds shed their feathers and replace them with new ones. The molt is induced by hormonal changes that occur as a result of the changing seasons. Various molt patterns are adopted by different avian species.

A synchronous molt occurs when a bird loses all of its feathers in a short amount of time. While this method may be quicker, it can also be more risky. If a bird loses all of its wing feathers (called flight feathers) at once, it cannot fly. Most waterfowl species such as swans, geese, and ducks are able to molt in this fashion because they can survive on land or water without flying. Birds of prey and songbirds, however, have a more difficult time surviving without flight. Many of these species need to hunt for their food or be quick enough to escape predators, making flight essential during all seasons. These birds, therefore, perform a gradual molt. In this process, they lose and replace their feathers slowly, often starting at one side of the body or wing and moving to the other. This allows the bird to maintain its ability to fly while still replacing all of its old, worn feathers.

Molt cycles are diverse, and vary with species, age, and individuals. An example of a unique molt pattern is seen in the arboreal woodpeckers. While most birds lose their center tail feathers first and progress out to both sides, arboreal woodpeckers do the opposite. They retain their strong center tail feathers to use for balance until the rest of their new tail feathers grow in.

For more information on molting, visit http://www.birds.cornell.edu/AllAboutBirds/studying/feathers/molting/document_view. And to see molting in action, visit the Kellogg Bird Sanctuary soon!

This goose is growing new wing feathers to replace the ones that have molted.