By Ranger Steve Mueller
Finding pretty feathers in the yard is something most of us have collected when we were children. It has been fun and challenging to identify who lost them. Blue Jay feathers are quite distinctive as are robin breast feathers. Many feathers can be quite challenging.
At this time of year I notice crows flying over with noticeable gaps in their wings. Two Mourning Doves passed without their long tail feathers. Some birds are looking rather beat up because they are missing feathers. It is molting season.
Most birds experience a complete molt where they lose all feathers after breeding season and before migration. It requires a lot of energy to change wardrobes but it occurs twice a year. The spring molt prior to migration or breeding is a partial molt where only some feathers are replaced.
When birds fly over missing noticeable feathers, it is the flight feathers we notice missing. If birds lost all there their flight feathers at once they would be grounded. That would spell death for many. They would starve before they could replace them. They also would not be protected from the weather. Feathers are important for flight and body feathers for insulation to maintain proper temperature.
Molting is orderly starting with primary feathers. Theses are the largest and most noticeable flight feathers. They are lost in succession from wingtip inward. As one is lost and replaced, the next one in succession is lost and replaced. When the primary feathers have been replaced, secondary feathers are replaced in the opposite direction. Secondaries are smaller flight feathers closer to the body. They are lost from close to the body outward toward the primaries.
It is ecologically important that most birds lose feathers in succession so they do not become flightless. They depend on flight for feeding mobility. Some birds lose all their flight feathers at once and cannot fly for weeks. One might think this would surely cause starvation or vulnerability to predators.
Ducks, geese, swans, grebes, and loons lose their flight feather at one time. They feed by diving or tipping bottom up to feed on the bottom in shallow water. Tipping end up to feed is known as dabbling. There are dabbing ducks like the mallard and diving ducks like the bufflehead and scaup that dive deep to feed. They become flightless for several weeks when molting but are able to continue feeding. When threatened they run across the water but do not become airborne.
It requires tremendous energy to molt. When birds migrate there energy needs increase 7 to 15 times over resting energy levels. They cannot afford to molt, migrate, or raise young at the same time. Each must be done separately and they have adaptations to survive in their unique nature niche. Loons molt after migration and ducks before migration. Some birds have a partial molt before migration, stop molting for migration and complete molting afterwards. It is typical for most land birds to complete molting before the fall migration.
Details of life are uniquely special and worth observing near our homes.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at the firstname.lastname@example.org Ody Brook, 13010 Northland Dr, Cedar Springs, MI 49319-8433.