With some of the photos that we have seen from our eaglets visit to The Raptor Center, I have been noticing some people in the chat room asking questions about feathers, so let's discuss them in this blog article. We will be noticing the repalcemnet of down feathers with other types that we will talk about below.
Every bird has several different types of feathers. Contour feathers are located on the body, tail and wings. These feathers help the bird stay streamlined and allow it to fly. Down feathers are fluffy feathers that grow near the skin under the contour feathers. The down traps warm air, insulting the bird in cold weather. Semi plume feathers are a combination between the down and contour feathers and like the down will help trap heat next to the body. Lastly, bristle feathers are located near the eyes or nose of some birds. Bristle feathers are stiff and may help keep bugs or other debris out of a bird’s eyes.
Bird’s feathers continuously wear, become soiled and lose their effective qualities, so birds replace feathers through a process called molting. Old feathers are molted and new feathers grow in place of them. S Some birds such as ducks, geese, swans, and pelicans are called “synchronous molters”, which means they molt all their flight feathers at the same time. During this period of time, they are unable to fly.
Raptors rely on flight for survival and thus have a different kind of molt. Raptors molt a few feathers at a time and are never flightless. In fact, they ususally molt the same flight feathers on each wing, so they remain perfectly balanced, maintaining their agility in flight even during a molt.
Generally raptors in this area will begin molting feathers in April and continue through the fall. Eagles don’t molt every feather during one season. It can take two to three years for a complete molt in many raptors.
A captive raptor might undergo a modified molt because factors like daylight, temperature, weight control and stress can impact the timing and duration of a molt.
How does a new feather replace an old feather?
The replacement feather grows inside a feather sheath, a thin, pencil shaped structure. This is known as a blood feather or blood quill. The sheath is soft and engorged with blood supplying the growing feather inside. As it grows, it displaces the old feather. When the mature sheath splits, it reveals the new feather rolled up inside. The length of time it takes for a new feather to grow depends where it is located on the body among other things. Some of the larger feathers, like flight feathers, may require up to 75 days to develop.