Those of you with a keen eye may have noticed recently that some of the forest birds in Shakespear Regional Park are looking rather scruffy.
The reason is that many of them are undergoing their annual feather moult. What you are seeing is old, worn and discoloured feathers being lost and replaced with new ones. Feathers grow from skin organs called follicles. The newly growing feathers push out the old ones which then fall off.
Feather moult is one of three energetically demanding parts of a bird’s annual cycle along with breeding and migration. While not all birds migrate, most breed and nearly all moult their feathers. The reason they need to moult is that feathers are made from bird-keratin, a similar material to our finger and toe nails, which is not living tissue. As soon as they have grown, they start to wear out under the effects of sunlight, rain, abrasion, dirt and the stresses of flight. By the time they are a year old they are often in poor condition.
Good quality feathers are vitally important for birds. They are used to maintain body temperature, cooling when it’s hot and insulating when it’s cold, their colours can provide camouflage or can be signals to other birds warning them to keep away or attracting potential partners. They keep out the rain and, of course, they enable flight. To do all this, birds have different kinds of feathers for different purposes. The flight feathers are the larger ones in the wings and tail while the body feathers cover and protect the skin.
Birds have different strategies for moulting their flight feathers. Ducks tend to replace all their flight feathers at once and so cannot fly until their new feathers are almost fully grown. Forest birds cannot afford to be flightless as they depend on flight to reach their food and to avoid predators. Instead, they moult their feathers in sequence, usually starting in the centre of the wing. They drop one or two feathers at a time and regrow new ones before dropping the next in line. Although there will be small gaps in the wings and tail during moult, the birds can still fly reasonably well.
Reduced flight ability means the birds tend not to sing as much and spend more time quietly feeding and resting so they can be more difficult to see at this time of year. But, as soon as the moult is complete, they will be looking their best and have the protection they need to survive the colder winter months.
For the photographers among you, this is a great time to head into the park and try for that perfect image.