Wednesday, March 17, 2010

The Arrival of the Second Egg.... and will there be a third?

Thanks again to CamFan in Oklahoma, who sent me this edited footage of the formel laying her second egg in the morning of March 16. Because we FINALLY had some sun in Philadelphia yesterday, the sun glare drains some of the color.

Following the camera footage is some commentary from John Blakeman as to whether there may be a third egg from the formel.

From John Blakeman:

"The likelihood of a third egg is now pretty good, I think.

Still, it was an inordinate period between the first and second eggs. We have to understand that the structural and molecular synthesis of an egg is a very metabolically intense process. All the calcium, for example, in the egg shells and dissolved in the albumen, which will be used to make the eyass's bones, came right from the bones of the formel herself.

The same is true for the lipids, the fats of the egg, that will power the eyass before hatching and eating. All of those nutrients came from the formel's body, not directly from her food.

The egg is assembled in a day or so during its descent down the single fallopian tube. It takes a lot out of the formel. That's why it's so important for her to feed well in January and February, to pack in reserves of all that makes the new eggs. If the heavy snows in February made hunting more difficult, because the rats, and mice couldn't be seen under the thick and pervasive snow, the formel may not have been able to load up enough fats, proteins, and minerals to make three eggs.

We won't know this for a day or more. I think one indication that another egg is on its way will be the manner in which the formel settles down on her eggs. Right now, she's just rather cavalierly descending on them. But she's not jostling or rocking back and forth when she descends. When we see that, we will know that she's entered the hard incubation period, where she will be extremely diligent in getting the eggs tightly positioned against her naked and warm brood patch on her belly and chest (beneath the feathers we see on the outside).

So, all we can do now is wait.

But even with two eggs, all should be well. As it happens, out here in the northern Ohio countryside, two eggs are the most common number in red-tail nests, with many nests having only one egg. There is actually a lot more for a red-tail to kill and eat in Philadelphia than out here in more "normal" red-tail habitat.

90% of the land here in the exceptionally flat Lake Erie Plain, is planted in row-crop corn and soybeans each year. These massive farm fields are biological deserts. There is nothing in them that a hawk or anything else can eat. Our hawks have to pounce on mice and voles (not moles, which are underground) they see scurrying around in grassy roadside ditches and rights of way.

Once again, here's to our Franklin Institute pair of red-tailed hawks. Little do they know (or care) about the hundreds of people watching them raise another family of eyasses.

--John Blakeman


  1. Thank you so much, John Blakeman, for all this fascinating information! Ann in Devon, PA

  2. And many thanks to CamFan in Oklahoma for video of the 2nd egg's arrival - I was away so am very grateful to see it! Ann in Devon, PA

  3. I didn't know this could be any more fun than it was last year....but it is!!!