The brood patch, the hatching muscle and what’s occurring inside our peregrine eggs

With freezing night-time temperatures there may still be some of you that are concerned about the impact of the cold on our peregrine family. As Nigel rightly pointed out in his recent blog, peregrines thrive in a wide range of climate zones across the globe. In terms of keeping their eggs warm, peregrines, like many other species have evolved a special adaptation – a featherless area on their breast called a brood patch.

Inside the egg, the developing peregrine chick has its head tucked under its wing

Inside the egg, the developing peregrine chick has its head tucked under its wing

In this area the skin becomes thicker and there is an increased blood flow to help transfer body heat from the adult bird to the embryos inside the eggs. The more regular viewers amongst you might have even seen the female lightly plucking her brood patch to help her keep the eggs warm.

Over the next few days it is likely that the female will switch from incubating the eggs to keeping her chicks warm – and I’m sure that thousands of you have been avidly watching the peregrine camera secretly hoping to be the first person to spot the chicks hatch.

Until that moment arrives, I thought it would be interesting to highlight just what is going on inside the eggs. Whilst they are being incubated, a developing peregrine chick has its head tucked under its wing. Chicks also have a large muscle called, rather appropriately, the hatching muscle, which runs from the middle of the neck right to the top of their heads.

When the eggs have been incubated for about 30 days (any-time now) this muscle starts to contract. This makes the chick’s head snap upward and the egg tooth, a hard pointed area on the top of the beak, comes into contact with the eggshell, causing it to crack.

As the egg tooth pushes against the shell it creates a small hole in the surface and cracks then begin to spread across it. A day or two after making the initial hole in the shell, known as a ‘pip’, the chick starts to move around inside the egg. As the chick turns around the egg tooth presses against the inside of the shell, eventually cutting a line right the way around. Once this is complete the chick is able to break out.

The chicks hatch over a period of a couple of days and generally the differences in size between those in a brood is smaller than in most raptor species – however, as we saw last year, one of the chicks may develop less slowly than others as they compete for food.

The chicks, called eyasses, are covered in white down to help ward off the cold. After between three and five weeks the down starts to be replaced with feathers.

At about the same time as the feathers start to appear the chicks will also start walking about and jumping around in the nest. As they grow, they will require more and more food and at this stage the female adult will begin taking a more active role in hunting once again – giving webcam watchers more opportunities to see the chicks in the nest.

At about five to six weeks old the chicks will start taking their first tentative flights – a quite daunting prospect I would imagine when perched so high on the ledge of the university’s Newton building. They will stay close to the nest, however, and remain dependent upon the parents for a couple more months,  meaning that we’ve got plenty of time to watch and enjoy their development between now and the summer.

Erin McDaid
Nottinghamshire Wildlife Trust

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54 Responses to The brood patch, the hatching muscle and what’s occurring inside our peregrine eggs

  1. Ann Amos says:

    That is very educational and really interesting – Many thanks.

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  2. Penny says:

    Thanks so much for that information – a little of which I knew, but a lot I did not! I can’t wait to see the first chick hatch and I spend every spare minute glued to the computer screen watching and listening – the housework can wait!

    Like

  3. Anne says:

    Thank you for all the information, I knew very little about falcons. I’m fascinated by their teamwork, have seen them swapping over to incubate the eggs, had no idea they did that.

    Like

  4. SueAtt says:

    I too knew very little about falcons so, as they say, you learn something new every day and it is greatly appreciated. These 2 birds can earn nothing but respect from us humans for the way they have worked together to look after their eggs, although the really hard work is yet to come! Can’t wait for the chicks to arrive – like everyone else, I am glued to the computer every available minute.

    Like

  5. StellaCorfu says:

    The parent sitting on the eggs this morning seems very restless – is this because he/she can feel movement inside the eggs?

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    • daventu says:

      We’ve noticed that too, she’s been doing an awful lot of shuffling! The incubation is 29-33 days and we estimate that we’re on about the 31st day – so it really could be any time now. Very exciting!

      Like

      • Beverley Clark says:

        I can see half an empty egg this morning!

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      • SueAtt says:

        Just seen a broken eggshell and I think I caught sight of a fluffy chick as mum moved around!! Hooray – at last!!

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      • Shirley Stirland says:

        we have a hatching,can see eggshell,chick must be under mum…Shirley

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      • StellaCorfu says:

        Am glued to my laptop here in Corfu – 2 chicks now. Looks like the second has only just hatched – seems a bit bemused to be out in the world! V excited!!!! (me, not the chicks!)

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  6. Graham E Smith says:

    I noticed on more than one occasion ,the nesting falcon apparently eating stones from the nesting area…….WHY./

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  7. Christine says:

    I have been watching the peregrines at Derby for a few years but have only discovered the Nottingham air this year, it’s very exciting because the Nottingham pair’s eggs are in front of Derby by a good couple of weeks. I understand that the parent bird can hear the chicks inside the egg before they hatch, is this true? It seemed yesterday that the female bird was ‘listening’ to something. I too am glued to the screen, it is very addictive !

    Like

  8. Penny says:

    10.00 am – the birds just swapped over – there is a chick almost hatched! Brief glimpse only cos they didnt leave it uncovered for long – anyone else seen it yet? My eyes are not deceiving me are they?

    Like

  9. PamUK says:

    I think we may have had a hatching…the egg nearest the camera appears to be broken, but I have only just logged on so no sighting of any chick yet !!!!

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  10. Paul Yeomans says:

    Well it’s Saturday 21st April at 10:45 and i’m sure i saw a broken shell, a chick hidden under the mum!

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  11. PamUK says:

    Definitely broken !!!!!

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  12. Sarah Glover says:

    At least one has hatched – have just been watching it 🙂

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  13. Beverley Clark says:

    I think a chick may have hatched as there looks like a half egg shell next to Mrs Falcon this morning! #
    🙂

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  14. Beverley Clark says:

    Definately just seen a chick!!! and two intact eggs…so exciting

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  15. Paul Yeomans says:

    Yep, one chick is out and another egg is cracked…

    Like

  16. Penny says:

    11.43 am – there is definitely a chick fully hatched and a second egg is now cracked and should be open soon – wow, this is amazing!

    Like

  17. Janet Graves says:

    Just been watching from Shropshire. Seen one chick and a second trying very hard to get out of the egg. Are these the first chicks to hatch this year? Thanks for the great camera work!

    Like

  18. PamUK says:

    Second egg well on the way to the hatch at 1.30pm

    Like

  19. sinbad1897 says:

    REALLY INTERESTING TIME NOW, ONE CHICK HATCHED REALLY EARLY THIS MORNING, ANOTHER CHICK IS ALMOST READY TO HATCH, MOTHER TURNED ROUND I COULD SEE THE EGG ALMOST CRACKED ALL ROUND AND COULD ACTUALLY SEE THE THE CHICK TAPPING THE EGG, EGG SHELL SPLINTERING. SO VERY LUCKY TO SEE, REALLY EGGCITED!!, NOW. SHE HAS BEEN CALLING THE MALE, SO WAITING IF HE BRINGS IN ANY FOOD.

    Like

  20. Kev says:

    second chick appears to be out at 2.43

    Like

  21. Beverley Clark says:

    Looks like a 2nd chick has hatched and the 1st one is now looking very white and fluffy 🙂

    Like

  22. Carol says:

    There are two hatched now (Sat) First sometime before 13.45 when I first was sure, and second by 14.44. I have screen grabs of both, in the second you can see both together. Congratulations! I’ll try to post them up for all to see.

    Like

  23. Carol says:

    see my screen grabs here
    nottmhatch1
    Nottmhatch2

    Like

  24. And a second one!

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  25. Beverley Clark says:

    So Amazing this afternoon…..the 2 chicks were left exposed for a couple of minutes while the adult fed off a bird n then flew off n back…1st chick eyes open 2nd eyes still closed.

    Like

  26. Jan says:

    2 chicks hatched today! Glued to the screen – so exciting and beautiful!

    Like

  27. Joyce S in Derby says:

    Just seen two chicks have hatched out this afternoon – Saturday 21st April, and mum has fed them on a blackbird

    Like

  28. I believe one egg has already hatched – I observed earlier at approximately 1pm. I feel honored to be able to watch these beautiful creatures!

    Like

  29. Damian Taylor says:

    First chick, whoop whoop!

    Like

  30. Graham E Smith says:

    Has everyone gone blind,;am I the only one to notice the half egg shell in the box.?….has one of them hatched and lives… or has one been born dead and the body eaten?
    Can one of the team tell us just what is happening…..on a regular basis ,Please.

    Like

    • daventu says:

      Hi – there are three lovely chicks in the nest box so far. Perhaps the mother was obscuring them when you first looked – she’s just been giving them a good feed!

      Like

  31. Paulew says:

    At least one chick seen at 18:46 on saturday 21st.

    Like

  32. s dickins says:

    how fantastic to log on and see two chicks at 6pm today Saturday

    Like

  33. Damian Taylor says:

    Hi, are you going to turn the sound on now we have chicks. Thanks

    Like

    • daventu says:

      Hi there – camera two always has sound on, we can hear them cheeping away right now! Try using Internet Explorer (if you’re not already) if you’re having problems, perhaps that will make a difference

      Like

  34. sinbad1897 says:

    Hi every one, mother just turned round, saw the third chick, part of the egg shell has come away, chick is still in the eggshell, looks lovely. Really enjoying them at this time. Cock bird has been back twice recently with some food, but flew away again each time, may see some feeding this evening. MALC. 16.00 ON 22/04/2012.

    Like

  35. Damian Taylor says:

    Have just seen 3 chicks, Sunday 4:35pm

    Like

  36. Damian Taylor says:

    You could see the third chick hatching out at lunchime as she fed the other two, amazing picture quality.

    Like

  37. Christine says:

    3 little hungry beaks shouting “me, me me”, come on number 4 !! don’t get pushed out of the food queue !!

    Like

  38. Lynn C says:

    Amazing site- the chicks and parents look so lovely and healthy! We are on “hatch watch” with our Great Spirit Bluff pair (cam) in the US. Now that I have found you I can watch in the daylight 24 hrs around! 😉

    Like

  39. Julie Robertson says:

    Have just watched mum feeding her brood, & noticed how careful she is to make sure all the chicks have their turn at getting fed! I thought the parents just shoved the food willy-nilly at the nearest open beak…. I have the Nott’m & Norwich falcon sites up at the same time, & we are still waiting for the first Norwich hatch – any day now!

    Like

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