Tag Archives: Feathers

Feather Close-ups

January 2. 2020: Decorah North Female preens upper tail coverts

by Sherri Elliott Bald Eagles have over 7,200 feathers (yes, researchers study and have counted them) and each plays a remarkable part in physiology, flight, and insulation. While Bald Eagles will go through multiple plumage changes before maturity at age five when heads and tails become fully white, head feathers and upper tail coverts can be distinctly colored and patterned as they segue or transition to body or tail. Thanks to the camera operators we have closeups of Mom Decorah’s

What are feathers? What is molt?

Feather Follicle

Eaglets go through two molts and three feather stages in the nest: natal down (and molt), followed by thermal down (and molt), followed by juvenile feathers. As of this blog, the Decorah eaglets are shedding the very last of their natal down and their thermal down is rapidly being replaced by juvenile down and feathers. We thought we would blog a little more about feathers to celebrate!  When we think about feathers, we tend to think about their qualities (light,

From bobble heads to eaglets: Natal down, thermal down, and flight feathers!

As the eaglets start to sprout feather cloaks, we’re getting questions about natal down, thermal down, and juvenile feathers. Unless otherwise stated, the information in this blog applies to altricial birds, although most research in this area has been done on precocial and semi-precocial birds like ducks, geese, and cranes. Altricial and precocial birds have some marked differences in pre-hatch follicular development and post-hatch molts.   Does thermal down sprout from natal down pores? Do flight feathers emerge from thermal down