Tuesday, April 22, 2014

April 22, 2014: Decorah Eaglet Update

April 12, 2014
April 22, 2014
The Decorah eaglets are 20, 19, and 15 days old respectively. What’s happened since April 12?
  • Grey, woolly thermal down has almost completely replaced the long white fuzz they hatched with. The last down to be replaced is on the top of their heads. Wigs or mohawks? Either way, we’ll soon see the down replaced there as well.
  • They weigh more. Based on Gary Bortolotti’s study Physical Development of Nestling Bald Eagles, D18 should weigh between about 2.5 and 3.3 pounds, D19 should be three to five ounces lighter, and D20 should weigh between about 1.5 and 1.9 pounds. 
  • Those crazy clown feet aren’t just our imaginations! The length of their foot pads and mid-toes have nearly doubled since hatch and their tarsi are almost adult thickness, if not length. Their foot pads and mid-toes will reach their maximum sizes when the eaglets are about 40 days of age.
  • All three eaglets are thermoregulating, an ability they gained around 15 days of age. Given their rapidly developing feet and new ability to maintain a constant body temperature, we’re seeing much more nest exploration, as first documented on April 17: http://youtu.be/ic_OJr9ioC8. We’re also seeing them spend more time alone.
  • They’ve become more coordinated. All three eaglets are becoming more proficient at sitting up, moving around the nest, and pooping without hitting Mom, Dad, or one another. Which doesn’t mean they never hit their parents, as this video of D20 getting Dad shows: http://youtu.be/-Fh_STMNp8w
  • Their visual acuity has improved. Our eaglets are watching and focusing on an incoming Mom and Dad, and eagerly reaching out to grasp food instead of waiting for delivery. We’ve talked about the virtuous cycle of feeding, growth, and development. The eaglets’ anticipation of Mom and Dad’s food delivery provides a great example of how feedings help drive development. 
  • We have our first 'sun pose':  http://www.ustream.tv/recorded/46510278/highlight/494408
  • We won’t see their little earholes for very long, so enjoy them now!
So what do we have to look forward to? We should start to see pinfeathers beginning to show as dark spots on the edges of our eaglets’ wings and tails, which happens at 22 to 28 days of age. Over the next 20 to 25 days, we’ll see a little more development in footpad and middle toe size, and a lot of growth in leg height. Our little eaglets are about to get tall! Stay tuned - we’ve also got a lot of play to look forward to as nest exploration expands and their ferocious growth rate begins to slow around 40 days of age.

[Thanks to Sherri Elliot and David Lynch for help and videos!]

1 comment:

Barbara OConnor said...

It's wonderful to see and hear their progress.