Apr 11 2017

Special Equipment For Warming Eggs

Published by at 7:15 am under Bird Anatomy,Nesting & Courtship

Dori rolls the eggs just before she resumes incubation (photo from the National Aviary falconcam at Gulf Tower)

Dori rolls the eggs before she resumes incubation (photo from the National Aviary falconcam at Gulf Tower)

To become baby birds, eggs must be warmed to around 98.6 °F and remain at that temperature while the embryos develop.  Adult birds that incubate(*) have special equipment to accomplish this:  bare skin on the belly called a brood patch.

We don’t usually see the brood patch because surrounding feathers close over it to keep the adult warm.  When a bird comes back to its nest to incubate, it opens its belly feathers to lay its bare skin against the eggs.  You may have seen peregrines open their belly feathers by standing over the eggs and rocking side to side.

Click on the link below to see an American kestrel’s brood patch and learn about this important part of bird anatomy.

Anatomy: Brood Patch

(*) p.s. In eagles and peregrines, both sexes incubate so both have brood patches but this isn’t the case with all birds.  In many duck species, only the female incubates so the males don’t have brood patches.


(photo from the National Aviary falconcam at Gulf Tower)

6 responses so far

6 Responses to “Special Equipment For Warming Eggs”

  1. Claireon 11 Apr 2017 at 9:45 am

    Can the Gulf Tower cam be zoomed in? Will be fun to start watching for pips next week.

  2. Kate St. Johnon 11 Apr 2017 at 4:45 pm

    Claire, the camera will be zoomed soon (if it hasn’t been already).

  3. Karenon 11 Apr 2017 at 4:53 pm

    Did anybody happen to notice the Hamar Eagle chicks?


  4. Stacyjon 13 Apr 2017 at 1:50 pm

    I love watching the falcons rock back and forth to settle over their eggs – there’s something adorably comical about it 🙂 Really interesting to learn there’s more to it than them just getting comfy!

    On a wholly separate note, was anybody else watching the Cathedral just now (around 1:25pm, Thursday)? Some huge bird got a little too close and one of the falcons chased her/him away – that was the first time I’d seen that! If anybody else caught the drama, any idea what kind of bird that was – a hawk? Turkey vulture? It was so big you could tell immediately it wasn’t one of the falcons … Well, whatever it was, Hope and Terzo did NOT put out the welcome mat! I felt lucky to have had the opportunity to see that live.

  5. Kate St. Johnon 13 Apr 2017 at 1:57 pm

    Stacyj, I wasn’t in the area but I’ve seen turkey vultures fly near the top of the CL. During the nesting season the peregrines chase them away. Go, peregrines!

  6. Stacyjon 13 Apr 2017 at 2:22 pm

    Go, peregrines indeed! While we were watching the excitement, another observer commented that our hockey team ought to change their name to the Pittsburgh Peregrines … I think could get behind that 🙂

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