Thursday, April 21, 2011

There were a lot of comments about eagle growth rate on Facebook this morning. According to Gary R Bortolotti, bald eagles may gain more weight per day than any other bird in North America. As in other animals, different body parts may reach adult size at different times. The growth of the legs will be complete about half-way through the nesting period, but the beak and flight feathers won't reach adult size until after the eaglets have fledged, or left the nest. In fact, an eagle's juvenile flight feathers are longer than its adult flight feathers, which it won't get until it is 3 - 4 years old.

The two eaglet pictures are the first and last photographs taken, over a period of slightly less than a month. That should give you some idea of the physical changes the eaglets go through as they grow, although the photo album makes it even clearer. Our little Decorah babies will be taking to the wing before we know it.I've got a Facebook album of Forth St. Vrain eaglet growth 2010, published here: FSV Album

The kestrels have laid a third egg. The photograph of the female kestrel clearly shows what I've heard called her "eye spots". Although no one knows for sure why she has them, the most commonly accepted theory is that they help frighten attackers away. Unlike falcons and eagles, she should lay a bunch of eggs, although not all of them will hatch. Again, unlike falcons and eagles but like many other birds, kestrels are sexually dimorphic in plumage - males and females have different plumage. Wikipedia reports that plumage has more variation between the sexes than size.  Click on the picture for a larger view.

The Decorah eagle babies seem to have gotten off to a nice start today - thank goodness the bad weather is gone!