May 22, 2005
Eagle Feather Types
First, some cam nest info. As of this coming week, the two oldest eaglets will be 12 weeks old and the youngest will be 11 weeks. Normally eaglets fledge anywhere from 9-13 weeks. They can become independent at around 16 weeks.
On the nest today we saw a parent eagle feeding a lone chick again. We also saw a cute shot of the youngest eaglet looking longingly over the side of the nest. It shouldn't be too long before he is flying himself.
And we have some interesting photos from the Vermont cam. One photo shows an eaglet with its wings wide, getting closer to fledging time. The other photo shows the little fish that come out on the eaglets' food tray.
Now onto the topic of eagle feathers...
Since all the eaglets, both here and in Vermont, will be flying soon, it seemed like a good time to talk about eagle feathers.
A full-grown eagle has over 7000 feathers on its body and has a large wingspan of 6-7 feet (upwards of 8 feet on the larger female). The eagle's large wingspan means it must use a great deal of energy to flap its wings. Consequently, bald eagles don't do that much flapping, but instead spend a great deal of their time soaring, which requires about a 20th or less the power needed for flapping.
Eagles use soaring or gliding when they migrate and also when they hunt and fish. Using thermals and updrafts, an eagle can soar continuously for hours.
Eagles have several types of feathers on their bodies, and these include the primary and secondary wing feathers, tail feathers, plume feathers and body feathers. The photo to the right shows the wing flight feathers and tail feathers with their parts labeled (click on the thumbnail).
The ten primary feathers are on the end of the wing and have different shapes, with the outer feathers being stiff and narrow; this is because they meet the air first and must provide wind resistance. These outer primaries are also notched and they can open like fingers, which can help a flying eagle to achieve lift and drag.
The inner primaries and secondary feathers are flatter and overlap to provide a smooth lifting surface.
An immature eagle's feathers will not take on the characteristic coloring of the adults until they are fully mature at about 4-5 years of age. Click on the thumbnail photo to the right to see a full set of bald eagle feathers. The image shows the different feather types, as well as the color variations between adult and immature eagles.
If you'd like to learn more about how eagles use thermals and updrafts to soar, then be sure to visit this website for more info.
In the next post we'll talk about the use of eagle feathers in Native American culture.
Until next time,
Lisa - webmaster