Tag Archives: Feathers

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

April 25, 2023: DH2 sprawls comfortably in the nest.

As DH2 starts to sprout pinfeathers, 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.   Natal down, thermal down, and juvenile feathers Does thermal down sprout from natal down pores? Do flight

Like water off an eagle’s back!

February 28, 2023: Like water off an eagle's back!

Mr. North incubates his egg while raindrops bead on his feathers and roll down his back. Fortunately, he has about 7,000 feathers to protect him from the weather. Different sources provide different answers about how many things birds do with their feathers, but all of them agree that insulation is important. The rain beading on Mr. North’s back shows us that feathers are insulative and water-resistant: the rain beads up on Mr. North’s back, but doesn’t reach his skin. Feather

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,