July 08, 2005

Feather Growth

First, I know that we have a lot of cam watchers from the U.K., so I just wanted to say how sorry those of us in the U.S. are for what occurred in London on Thursday, and we hope that all of our watchers, and their family and friends, are safe at this time.

sleeping2.jpgWe've updated the Gallery with lots of interesting photos that offer some insights into how the chicks are developing. I want to thank all those who took the time to send in such great shots. When you're looking through the latest updates, notice the back-to-back shots that sometimes show action in the nest. In several places we have two or three shots in a sequence that capture an interesting event.

If you look carefully at the Gallery, you can see that the oldest chick is often fed first. This is the way of life in a raptor nest. Fortunately, we don't see a lot of aggression between the chicks, and the mother osprey appears to feed the second chick regularly, as the youngest is growing big and often has a full crop.

We also see some shots providing confirmation that the chicks are beginning to stand up, as well as lift and exercise their wings. This activity will increase in the coming weeks as the chicks prepare for fledging, which could be less than a month away.

We can also see from the photos that the mother osprey still seems to be bothered by activity near the nest -- most likely the eagles. The chicks appear to obey her most of the time and stay down in the nest when she's gone.

Another interesting set of shots we received include a humorous -- although unfortunate -- sequence showing the mother osprey getting accidentally sprayed. Luckily her head wasn't up. :-)

Finally, we can see some good comparison photos that indicate that the oldest chick is ahead in his feather development. His downy fuzz is clearly being replaced by growing feathers.

Melanie Lynch, our friend from the Chesapeake Bay Magazine, kindly loaned us a pair of photos she recently took on an osprey banding trip, and the photos offer a terrific close-up view of two osprey chicks in varying stages of feather development.

shaft_th.jpg   shaft2_th.jpg

In the photo on the left (click on the thumbnails) a younger chick is just starting to see his blood feathers or pin feathers develop. And on the right, a slightly older chick is seeing even more feather growth.

Feathers come from follicles (tiny bumps) that grow in rows or tracts on the bird's skin. When the feather first comes out, it is rolled and protected inside a tube-like sheath that contains blood vessels, which nourish the feather's growth. The bluish-coloring in the sheaths is blood; this is why they're called blood feathers. You can see the blue sheaths in both these photos.

Once the feather has developed and burst through the sheath, the protective tube will fall away or possibly the bird will pull it off while preening. The blood vessels will have withered and the quill will be the white color we are familiar with seeing.

Blood feathers are sensitive and if broken or injured, can cause severe bleeding and even death. When a blood feather is broken, it must be removed so the follicle can close and a new feather can be born.

Note that in the second photo featured above, the chick's feathers are not solid brown like an adult's, but instead have tan tips. Young ospreys have a tan coloring at the tips of their feathers that lasts until they are about eighteen months old. It is believed that when the young ospreys fledge, the tan coloring helps notify adults in the area that the birds are immature and not a threat to the adults.

Here is a wonderful photo of a young osprey chick from Martin National Wildlife Refuge in the Chesapeake Bay. The Blackwater Refuge staff oversees this refuge, which is popular with ospreys. The photo offers a close-up look at the tan and brown feathers of an immature osprey and shows what our young raptors will soon look like.

Until next time,
Lisa - webmaster

Posted by Webmaster at July 8, 2005 04:57 PM