Friday, April 12, 2013

Incubation is going well

The Franklin Institute hawks are well into their second full week of incubation.  Watching hawks (or any birds) incubate eggs has been likened to watching paint dry.  Not much outwardly happens.  This is pretty much the unchanging view on the nest cam.

          Della Micah

From the ground looking up, she is tucked down in the nest bowl with only her head showing.  

           Kevin Vaughan

The big excitement is when T2 flies in to give Mom a break from sitting on the eggs.  This is when we often get a glimpse of those precious eggs around which they tiptalon so carefully.

         Katy Mae 

Once he arrives, she is outta there!  She has complete faith that he will cope with whatever antics the eggs might get up to.  T2 looks a little less certain!

           Tess Cook

He often arrives with his trademark gift of greenery...

           Kevin Vaughan

... and he now has clearly figured out how to break off large pieces with no problem.

          Kevin Vaughan 

He is also becoming increasingly comfortable with sitting on the eggs, and Mom sometimes has difficulty getting him up and off them when she returns from a break.

           Kevin Vaughan
 
          Kevin Vaughan

Sometimes, his gifts are edible and those get snatched immediately from him.

          Kevin Vaughan

 Definitely grab-and go food!

           Kevin Vaughan
          Kevin Vaughan

She often heads to the flat top of the nearby Civil War monument to eat.

           Kevin Vaughan

          Kevin Vaughan

          Kevin Vaughan

The hawks also use the monument as a food cache, and one morning, Mom cleaned up this large, unidentified food item.

          Kevin Vaughan

          Kevin Vaughan

Sometimes, after T2 has caught prey, he will first take it to the monument and eat some of it...

          Kevin Vaughan

 ... before heading over to the nest to take the rest back to Mom.

          Kevin Vaughan

          Kevin Vaughan

Other times, T2 will simply perch there surveying the city scene.

                          Carolyn Sutton

On Wednesday morning, T2 was very late for his changeover at the nest.  Mom finally had to stand up and stretch her legs...

           Della Micah

... then her wings

           Della Micah

           Della Micah


T2 -- call home!

           Della Micah

This is how she looked from the front while waiting for T2, tapping her talons, perhaps?

           Kevin Vaughan

Eventually, she had no choice but to settle back onto the eggs and wait for him to show up.

           Della Micah

Understandably, hawk watchers become nervous when T2 is not where he should be, as we well remember the anxiety and sadness of last year when we watched and waited for Dad, and he never came back.

The following morning, though, all was well in hawkdom as T2 atoned for the previous day's tardiness by bouncing in just after sunrise.

           Katy Mae

During this incubation period, hawkwatchers often notice that as Mom settles back onto the eggs, she wriggles and arranges herself quite carefully.  What she is doing is positioning her brood patch on top of the eggs to provide maximum warmth.  The brood patch is a bare area of skin under the belly feathers.

Here's an image of a red-tail's (not Mom) brood patch, visible only when the wind blows her feathers apart.


Most female birds develop a brood patch during the breeding season. Changes in hormone levels during the nesting season start the process. The tissue in the belly area swells, becomes moister, and the blood vessels that feed the skin expand. These changes make the skin of the brood patch almost as hot as the body's interior. When she sits down on the eggs, she wriggles her body back and forth until the skin makes best contact with the eggs.   That wriggling also turns the eggs so that all parts of the developing embryo get exposed to the warmth.

John Blakeman offers these additional comments:  "Formels, without question, have large, naked brood patches, against which they tuck and rock the eggs into direct contact. But I don't think (but don't yet know with exhaustive knowledge) that tiercels have a full brood patch. It appears to me that they lose only a reduced quantity of the downy breast feathers; that the eggs do get tucked up onto the breast, but not as well as with the formel's naked brood patch. I never saw a brood patch in the sitting tiercel in my Red-Tail breeding project. The brood patch of the sitting formel was very obvious."

Mom's brood patch is under those ruffled feathers, and you can almost see the pinker skin lower down.

            Kevin Vaughan

Earlier this week, instead of flying into the nest, she landed on the ledge alongside the nest, bringing back memories from last year when she picked up the rat food drops

           Kevin Vaughan

New hawk watchers will see this ledge used extensively later in May and June when the eyasses are old enough to explore outside the nest.

           Kevin Vaughan

What an imposing, beautiful hawk Mom is.

            Kevin Vaughan

                Kevin Vaughan
 
Whatever the excitement or travails of the day, by night fall she is always on the nest protecting the eggs from the chilly nights we're still having here in Philadelphia.

        Katy Mae

Every day, Kevin Vaughan shares his incredible images of these hawks on the Hawkaholic Facebook page Here are some recent spectacular ones!

Here's T2:

           Kevin Vaughan

           Kevin Vaughan

 T2 rarely looks intimidating...

                         Kevin Vaughan

                               Kevin Vaughan

            Kevin Vaughan

 ... but in this image, he looks unusually fierce.
 
           Kevin Vaughan
 

And now for Mom:

            Kevin Vaughan

She almost always looks fierce, but here's a more pensive view.

                                             Kevin Vaughan

          Kevin Vaughan

          Kevin Vaughan

          Kevin Vaughan

            Kevin Vaughan

 

5 comments:

  1. Always a pleasure to read your updates Della. It IS interesting that the males always have the sweeter expression than the females. I wonder how Barnes feels about all the greenery they are losing? ;-)
    Ann F.

    ReplyDelete
  2. This was a fascinating post. I recall John Blakeman telling us about the brood patch, but this discussion gave me more information. The photo showing it was great. I enjoyed Kevin's photos, and the one that Carolyn took was gorgeous - T2 surveying the scene at the top of the monument.
    I love your writing and story-telling ability, but this time was special. You managed to make the waiting game a pleasure!
    Thanks, again.
    Joyce

    ReplyDelete
  3. WOW.... this is taking FOREVER!!

    ReplyDelete
  4. Once again, great writing and story telling. I love the part about how T2 'will cope with whatever antics the eggs might be up to'. Because we all know how crazy unhatched eggs can get! Thanks Della, and Kevin, and all the other photographers, as always. Great jobs all around. Jan B. from CA

    ReplyDelete
    Replies
    1. Reading this post and looking at all the amazing photos put a much needed smile on my face. Thank you
      Nikki G from NJ

      Delete