Thursday, April 7, 2011

Caring for eggs in 2011.

With all the excitement at the eagle’s nest, our very diligent peregrine parents have been nearly forgotten. What good parents they are! 'Mom' spends about 70% of the day on incubation duty. Generally, she will spend the night with the eggs while 'Dad' takes short turns during the day to give Mom a chance to hunt on her own. Whoever is on the nest will change position about every 30 minutes and may turn the eggs at that time. They turn them to ensure that they are equally heated and to ensure proper development of the embryo inside the egg. If the egg is not regularly turned there is a danger that the membranes surrounding the embryo will stick to one side of the egg. We also observe that the parents leave the eggs uncovered for short periods of time. This behavior also contributes to egg development by allowing increased oxygen to flow across the porous shells thus increasing the oxygen in the fluid inside of the egg.

Sometimes when the female returns to the nest she seems to be very anxious to kick dad off the nest and get back to business. Last week Thomas, a regular BRI Peregrinecam watcher, captured a great series of photographs showing the female returning to the nest. He posted these photos to BRI's online community.

Once back on the nest, ''Dad' or 'Mom' takes quite a bit of time settling back onto the eggs. You will see the parent with its tail in the air, working to settle its breast firmly on the eggs. Both the males and females lose feathers in the center of the breast to develop brood patches for incubation. The area becomes increasing vascular and swollen with fluid creating a surface that allows more efficient transfer of heat from the parent to the eggs. Generally the patch is not visible on peregrines because the remaining breast feathers in adjacent rows cover the area. If you have never seen a brood patch, go to Google Images and search for brood patches. Although I have not found an example of a peregrine brood patch there, there are many examples from other bird species. They are not a pretty sight but are interesting. Patrick first described them to me as looking like a large boil!

If you have questions about this pair or peregrines in general, please send them to us. We will do our best to answer them in the next blog.

Happy falcon watching,
Kate Rotroff
BRI Peregrinecam Ambassador


  1. Very interesting, I did not know about them letting the air flowing across the egg to increase the oxygen internally. Thanks

  2. Thanks Kate, so nice to have these blogs and the information they contain. Patrick invited us over here to meet you and I'd like to invite you over to the Ning to talk more with us and share your expertise.
    J. in S.P.ME

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  4. Hi Kate, So our little PF from 2009 is free once more and off on more adventures. I was wondering if you could talk to us a bit about how a Peregrine would go about establishing a new territory? What would they be looking for and how big might the territory be? Seems daunting to be flying free, yet have so much to do for survival. Does the male set up a scrape area and then introduce a female to it, do they do it together...and when might this young peregrine start looking for a mate? Phew!! Thanks so much for any info you can give. have fun today
    J. in S.P.ME

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