Friday, April 30, 2010

A day in the life of the eyasses - eat, eat, eat, sleep

The eyasses are now over a week old, and grow bigger and stronger each day. The parent hawks are doing a superb job satisfying their offsprings' insatiable hunger.

Here are the eyasses lined up waiting for the next morsel. Yesterday's sun created some glare which has washed out the color in these images.

The tiercel not only brings the food to the nest, but he helps the formel feed the eyasses. Here we can see the difference in size between the parents.

The eyasses wait patiently for the next beakful. Because the tiercel is doing such an excellent job bringing food to the nest, we have so far not seen too much pecking and food-aggression amongst the siblings.

The parents also share the food generously with each other.

Despite his almost non-stop hunting activity, the tiercel still finds time to bring back some greenery as well to the nest. What a guy!

Though the larder is overflowing with food, here comes another mouse.

Because the third egg hatched almost two full days after the first two, that eyass (in the middle below) is slightly smaller than the others, and sometimes has to wait till its siblings can eat no more before it gets its turn to be fed.

Here is the formel reaching around the others to feed the smallest one.

The tiercel is a devoted parent. Not only is he hunting non-stop for his family, but when he brings the prey to the nest, he also helps tear it up into tiny morsels and then carefully feeds the babies.

In an extraordinarily tender moment, he also fed the formel, making sure that she was getting her share of the food.

When everyone has eaten, the haggards (parent hawks) take a break from the nest, leaving the eyasses crashed out in another food coma among the gory remains of their rabbit lunch.

A family portrait!

Monday, April 26, 2010

Superhawk - Dad of the Year!

Watching the nest this week has provided a number of "Viewer Discretion Advised" moments as the tiercel (Dad) brings increasingly large prey animals to feed the ravenous eyasses, and we see the hawks efficiently defur, defeather and shred the prey into eyass-sized mouthfuls.

The eyasses are fed till they can eat no more, and then they fall into food comas among the gruesome remains of their meals.

The eyasses are now getting so strong that one of them started to feed itself today in the disemboweled belly of a squirrel.

None of this would happen if not for the herculean efforts of the tiercel to provide food for his family. John Blakeman gives us this account of the extraordinary job Dad is doing:

"The tiercel is now in complete, full-time hunting mode. We are not likely to see him bringing any cursory twigs or leaves to the nest anymore. Now, for the next two or three weeks, it's crunch time for Dad. He's got to feed his rapidly-growing eyasses, all three of them, and his already full-sized formel (bigger than he). The tiercel is the lighter-colored bird on the left.

To do all of this, he will have to hunt with extreme agility, cunning, and success. He has to know were to park himself during his perch-hunting episodes so as to optimize his chances of seeing and capturing anything. He's not merely wandering around the Parkway neighborhood of Philadelphia hoping that something might turn up. Very much the opposite.

As I have mentioned before, red-tails are not intellectually gifted in any way, except one; their small brains are devoted to remembering where and when and how prey were seen and captured. The stories of how hawks so remarkably recall and often replicate prey captures from previous years are well known to falconers, who see this first hand. The stories are almost unbelievable, with hawks returning to previous kill sites after an absence of a year or longer and hunting --- successfully --- just as in the distant past.

Red-tails seem never to forget where, how, and when they've captured prey. The Franklin Institute tiercel has been killing animals there for at least two years, and as he does his daily circulation of his local hunting areas, he knows from experience where the prey animals can be found.

And he also knows the best way to capture these prey animals. He hunts and attacks rats one way, squirrels another, and he takes pigeons very differently from mammals.

From his provisioning of his family this week, he knows exactly what to do. Again, it's no longer time to be messing with sticks and leaves and other vegetation. Now, it must be only food --- for everybody. Until the formel can confidently head out and hunt for herself, leaving the eyasses safely and comfortably back at the nest (which won't be for at least two weeks), the tiercel has to feed five hawks, his entire family.

Remember, the tiercel is a bit smaller than the larger, more powerful formel. In the coming days, he's got his work cut out for himself. But he's a winner. He was a good provider last year for a family of five, and this year, with even more experience, he'll continue to be the family prey-winner (hawks don't eat bread).

In our wonderful camera views, we get to see only the formel and eyasses, with scattered appearances of the tiercel. In his visual absence, let's not forget that he's out keenly searching his selected landscapes for food for the family. He's a profound hunting and killing machine right now. Everything depends on the food he brings to the nest.

So far, he's a star.

As for the three eyasses, they are all very healthy and strong. Not a weak one in the clutch. By the end of the week, everyone will be amazed at the obvious growth that will be seen. From now on out, almost till fledging, the eyasses will grow at a phenomenal rate

--John Blakeman

Let's hear it for the formel, formerly known as Dad and the tiercel, formerly known as Mom

And that title is not a misprint!

Last Friday afternoon, Kay and I were privileged to be able to visit the Boardroom at the Franklin Institute to see the hawks on their nest.

There is a long privacy screen across the alcove where the window is, with a small gap at each end through which one can look at the nest, or aim a camera lens. There is absolutely NO stepping in front of the screen allowed. We had a good view from either side, and Kay was able to photograph with no disturbance to the hawks.

As exciting as it was to see our hawks up close, that paled into comparison with what we discovered when we saw them side by side at our eye level.

All this time, we have been misidentifying the formel and the tiercel!

The bird we had always thought was the tiercel (dark chin and larger, darker chest streaks) was sitting on the nest when we arrived.

Then the bird we had always thought was the formel (light chin, and paler chest with delicate spotting like a necklace) arrived carrying prey, and immediately we could see that that bird was much smaller than the one sitting on the nest.

When we saw them
standing up side by side, it was clear that the white chinned one was definitely smaller, and was doing tiercel-type work: hunting and bringing prey to the nest, and the dark chinned one was much bigger and was doing formel-type work: sitting on the nest with the baby eyasses.

Though we were flabbergasted to think we had had them backwards all this time (much like discovering the earth was not flat!), the longer we watched, the clearer it became that the one who is doing all the sitting on the nest - Mom, the formel - is the dark chinned one.

How could we have made such a mistake?

I think because neither Kay nor I was involved with the hawks last year at this stage, we never saw the formel on the nest with the eyasses with the tiercel coming in with food. It was only when the eyasses had fledged and the Ustream camera could no longer see them, that we started to document their activities.

We rarely saw the haggards in proximity to each other, and when we did they were flying or were high up in trees or on ledges. At some point during the summer, we ascribed the darker coloring to the tiercel, and the lighter to the formel, but neither Kay nor I can recall why that was. On Friday, however, when we saw them side by side on the nest, only about four feet away from us, there was no mistaking who was who!

So I hope this discovery will help us settle into a clearer understanding of which bird we are watching. I am SO sorry to have caused such confusion!

Sunday, April 25, 2010

Saturday's drama with the black, plastic bag

Because of weekend activities, many people (myself included) missed Saturday afternoon's drama when the formel got her leg caught up in a plastic bag.

Thanks to hawkaholic Karen McCunney (karenm152 on the Ustream chat) who wrote up this account, and to CamFan for the screen grabs (an hour behind in CST), we can get a sense of how close a call this was for the formel. Please feel free to add any comments for clarification!

Following this account is some video from today, showing the formel no worse for wear, feeding all three of the eyasses until they fell into a food coma!

From Karen McCunney:
"Saturday was an exciting day for all of us Hawkaholics! The formel somehow managed to get a small, black plastic bag wrapped around her left leg late in the afternoon. Watching her, you could tell that it was bothering her because it moved every time she did.

The tiercel brought food to the nest and she continued to feed the eyasses, bag and all.

She eventually flew off with the bag still attached to her leg and the real drama/trauma began. On the Ustream chat, we were speculating on all of the bad things that could happen to her. The biggest fear was that the bag would get caught on something and injure her.

The formel did not return for over two hours. The tiercel stayed in the nest standing sentry but was not sitting on the eyasses.

He fed them briefly twice while there but wouldn’t give up his post! We were afraid that if the formel did not return by nightfall, the eyasses would not make it through the night without her warmth.

The Franklin Institute became aware of the situation and joined in on the chat room trying to calm everyone! They assured us that because her beak could tear through skin and sinew, a plastic bag would not be a problem. One of our regular chatters also called Rick from the Schuylkill Wildlife Rehabilitation Center. Rick said that if the bag were still on her leg by nightfall and the FI would give him permission, he would remove the bag.

It was a harrowing time for all of us watchers. I can’t believe how attached we’ve all become to our family of red tails!

The formel eventually returned without the bag. Or was it the formel? There was a great deal of discussion over whether it was truly she or the tiercel. Whoever it was, this bird settled down to cover the eyasses.

We were somewhat relieved but would not be convinced until we saw both haggards at one time.

A few of us had to leave for previous commitments. (Imagine that!) I know I was not enjoying my party because I was so worried about the formel. What would happen to our eyasses if she never came back? Would the FI have to step in? Was she being rescued as I sat and chatted with friends?

Those who didn’t have previous commitments were glued to the screen. Speculation continued throughout the evening until there was a brief glimpse of the other parent.

At 9:30 PM, long after the sun had set, many of us were still checking in to see if all was well with the hawks. Everything seemed to have settled down by then. Whew!

Now, we can relax until they fledge….. but keep your Maalox nearby!"

-- Karen McCunney (aka karenm152)

Here is the video from Sunday afternoon (thanks, CamFan, as always) of the formel feeding all three hungry eyasses.

Thursday, April 22, 2010

The third egg hatches!

As the sun rose on the nest this morning, we could see what looked like an eggshell lying beside the formel as she sat with the eyasses underneath her. Did the third egg hatch overnight as the others had?

As the formel moved, we had tantalising glances of this shell but it was hard to be sure if it were empty. The formel seemed to want it out of her way rather than underneath her, so it looked pretty definite that it was an eggshell.

But until we saw that third eyass, we couldn't be sure. Then the formel stood up, and there was #3!

Thanks to CamFan in Oklahoma we have video footage of the first sighting of all three eyasses. The newly hatched one is little less active than its older siblings, but it did get some food at the next feeding.

Because it is two days younger, smaller, weaker than the others, it will have to fight hard for its fair share of food.

Wednesday, April 21, 2010

Why the hawk brought leaves instead of food to the nest

Yesterday, when the food service to the nest was still getting up to speed, we noticed greenery arriving instead of a mouse or pigeon. Was the greenery some kind of camouflage for the baby eyasses?

John Blakeman gives us this fascinating insight into the mindsets of the parent hawks:

"No, the leaves brought to the nest were not intended as camouflage. Clearly, they didn't obscure our view of the tiny eyasses, and neither would they have done that for any passing nest raider, such as a crow.

But we shouldn't presume that the eyasses were unprotected in the parents' absence. Very much the opposite. Although the formel stepped away for an interval, be assured that she was in full view of the nest and had her eyes on all activity in the nest region. Had a crow or any other bird started to fly anywhere near the nest, she would have responded instantly and powerfully.

And the tiercel, too, during his long, all-afternoon absence, was almost surely in direct eye contact with the nest, or at least the general nest territory, where he could quickly go in and push away any intruders. We are getting to watch but a square meter of the nest surface, while both of the haggards are surveying the entire airspace of this part of Philadelphia.

As I watched the formel sitting on the nest yesterday, eagerly awaiting some food (for her eyasses, not for her -- she can easily and comfortably go two or three days without food), I noticed her visual attentiveness. As a falconer who has watched my red-tails hunt right from my fist, I'm aware of the hawk's slight nuances of increased interest in the landscape in front of her. The formel was keenly aware of and watching everything around her nest yesterday.

Why did the tiercel bring some leaves, instead of some food, to the nest? Doesn't make sense, does it? But in fact, these birds are not acting on "good sense" or rational thinking in any human manner. Their brains don't work that way. They can't. The hawk brain is rather small, and utterly incapable of the deliberate (but simple) thoughts that went through our heads yesterday as we anxiously awaited food all afternoon for the now-hungry (but still safe) little eyasses.

Red-tails are mostly eye ball, not brain. Their eyes are almost as big as a human eye, taking up at least two-thirds of the cranial space. The brain is only a small organ at the back of the head. The rest of it is a pair of powerful telescopic eyes. Consequently, the behaviors of the hawks are almost always -- with one exception I'll mention -- very "ritualistic." They almost clumsily "go through the motions" to do things like feeding the eyasses.

When you watch the formel feed the eyasses, she always gets the job done, but in fits and starts and awkward and inconsistent motions. Let's face it. She's a bird brain. She (and her tiercel) can't think very clearly and can't act very deliberately. They ritualistically go through the motions when incubating, rolling the eggs, and feeding and protecting the eyasses.

That's why the leaves were brought to the nest. It was "something do do." In human terms (more so than I, as a male would like to admit), the tiercel, meagerly, was thinking, "Hey, the formel's really got something going there on the nest. I'd better DO something. Now just what can I do? Hey, I'll bring her a beak-full of leaves. She liked that a month ago. That oughta do it!"

We males are, by and large, mentally disadvantaged in figuring out the feminine mind and its enigmatic perspectives. It's the same with the tiercel. He's still scratching his head trying to figure out what to do now. "Oh, I'd better bring a bunch of food over to the nest, I think."

But there is one area of thinking where the red-tail and all hawks excel. Here, I'll mention it only briefly. It should be a chapter or two in my book on red-tails that I will be writing.

Red-tails are simply brilliant hunters, spending hours each day observing prey and calculating how to efficiently and successfully capture, kill and retrieve food. Nothing haphazard or random or ritualistic with this. It is with great cunning the tiercel has learned to capture energy-dense city pigeons, birds that could easily and otherwise escape a slower, bulky red-tailed hawk.

And that's why I so much would like to see postings on exactly how urban red-tails capture pigeons. Clearly, they do it with calculated cunning and directed ambush. Smart birds, them -- in this unique regard."

--John Blakeman

Dinner is Served...... Finally

It was thrilling today to see the two hatched eyasses looking so strong and active. As the hours passed, however, it was noticeable that the tiercel (male) seemed to be missing in action. He was supposed to be bringing back food for his mate, and food suitable for the eyasses' first meals.

The formel seemed increasingly intent on the surrounding airspace, as if looking for him, and she flew off the nest a couple of times, leaving the eyasses alone and unprotected. In the remarkable video below, we see the formel returning to her still only hours old hatchlings carrying a sizeable leafy branch which she then gently places over them, as if to camouflage and protect them.

Was she thinking that she had to go out on a hunting expedition for food, and needed to protect the defenseless eyasses?

Just as it was starting to look quite serious for the welfare of the eyasses, the tiercel zoomed in with a large pigeon-sized meal for his formel. If we could read beaks, the formel was probably saying something along the lines of, "Where the HECK have you been? And how am I supposed to feed these little guys with that tough old bird? Get back out there, and bring me back some eyass food, and be quick about it!"

The video clip below shows the tiercel making two food deliveries, the second of which is a small mouse, in which the formel immediately shows great interest and then takes to carefully feed the now very hungry eyasses.

Following the video is commentary from John Blakeman on these events.

John Blakeman comments:

"Actually, I think there's some real science or raptor psychology behind all of this. None of this is random, by-chance stuff. This sudden change in hunting, feeding, and prey provision patterns of the tiercel I think relates to the new eyasses and the new behaviors of the formel. I saw her looking with an intensity this afternoon that she never expressed during incubation. She was acting differently, and the tiercel could have seen and understood that.

And he is probably acting differently, too. His hunting may be different, and his impulses to bring prey to the nest are now different. In short, it may take a day or so for him to settle into new hunting and feeding patterns.

He now has a giant task for the next 10 to 14 days or so, where he has provide for two haggards, his formel and himself, and two fast-growing eyasses. The formel won't be off hunting for some time yet. Lots of weight on the tiercel's wings now.

The eyasses, as much as we were concerned, weren't in any real danger. They had been fed earlier in the day, and in the first day or two they are not metabolically cranked up to full speed. If they were still in the egg, things would be gentle, quiet, and requiring only low energy inputs. That's one reason they spend so much time all flopped over, looking almost dead sometimes for the early days out of the egg.

I saw no indications of pipping in the remaining egg, so it may not hatch tonight. The other two eyasses didn't read my message about how long it can take between pipping and hatching. They just jumped right out of the egg last night.

One last conjecture. The third egg is very likely to hatch. I hope it does. But if it doesn't, I'm certain that its failure would reflect the harsh hunting weather in March, preventing the formel from getting a full and continuous load of egg-making food.

Oh, I did see the formel talk to her eyasses this morning. I saw the very slight beak movement that red-tails make when they are quietly uttering something. It was just plainly cute -- and I was the only person who understood, perhaps."

--John Blakeman

Tuesday, April 20, 2010

Bobblehead hawks (still only two)

Here is some more footage from earlier today of the newly hatched eyasses starting to get a little more active in the nest. Following the video are some pictures taken later today.

This is just before the second feeding. The formel continued to feed them from the remains of a bird lying just in front of the eyasses.

The formel feeds tiny morsels to her eager offspring, while the remaining egg.... sits there.

When her hatchlings finally can eat no more, she feeds herself. The tiercel is now hunting for the entire family.

The unhatched egg is in the thick of things!

Suddenly, the formel takes off and the eyasses are left alone for one... two... three... four... five long minutes.

How do you spell r-e-l-i-e-f? Seeing the parent land back on the nest!

By the middle of the afternoon, the eyasses had managed to turn around to face the camera. And at 3:45 PM still only two eyasses.

Gene Mancini from the Franklin Institute has posted some additional pictures on the Facebook Hawkaholic page.

First two eggs have hatched!

Congratulations to the Franklin Institute hawks who have successfully hatched their first two eyasses.

The eggs hatched overnight, and below is video footage (thanks so much, CamFam) of what we think is their first feeding.

One more egg still to hatch.

Monday, April 19, 2010

Is the hatching starting?

Over the past few hours this morning there has been a lot of activity on the nest - five nest exchanges, three deliveries of greenery, two deliveries of sticks, and a food delivery.

During one of the nest exchanges the eggs were clearly visible and a possible pipping could be seen on one of the eggs. Thanks to CamFan, we have that footage (CST).

Following the video footage is some commentary from John Blakeman about what it might all mean.

John Blakeman comments:

"I, too, saw all that activity and the formel's extended settling behavior this morning.

I think all of this is a response to pipping sounds and perhaps even some very soft vocalizations from the eyasses yet in the egg.

Both haggards, when incubating, can feel the movements of the unhatched eyasses, very much as a human mother can feel the movements of her unborn baby.

I'm certain that this begins to turn on mothering behaviors; hence the increased activities. The formel realizes now that she's not just sitting on three inert white objects that feel good to have against her naked brood patch. Now, things are discernibly (but invisibly) happening down there.

With new sounds and tiny motions in the egg, a whole new set of behaviors is being prompted. Motherhood is a profound phenomenon, across all species. (We men pretty much don't get it, just inexplicably watch it.)

I couldn't tell from the photos if an egg had actually been pipped. Could have been just some dirt in the nest. Hard to tell.

But as the formel knows and shows, things are starting to happen down there. We are all excited

--John Blakeman

Sunday, April 18, 2010

What lies ahead with the hatching

If all goes well, we should soon start to see the eggs hatching. Here is some knowledgeable commentary from John Blakeman about what we will be seeing. I have added a couple of images by way of explanation, but these are not of hawk eggs or eyasses.

From John Blakeman:

"It would be well for everyone to ponder what’s now ahead.

We all expect just a wonderful experience as we witness the hatching, with the first indication being that pipping has begun. Pipping is when the little eyass inside the egg begins to thrust its beak out at the end of the egg and will create a small crack. That’s pipping, the cracking of the egg, and it’s very important.

It’s done by the "egg tooth," a slight temporary projection on the top of the beak.

With a rounded bill, it would be otherwise very hard for the little eyass to poke any sort of hole through the egg shell. But the slightly pointed egg tooth will allow the weak eyass to accomplish this.

That will be the first sign of hatching. Someone will see the slightest crack on the end of an egg. Everyone will get understandably excited.

But then disappointment will set in. We would all expect the little eyass to continue to break open the entire egg after the first pipping and step right out into the world. But it doesn’t (and shouldn’t) happen that way.

After pipping, the little eyass stops pecking at the egg shell and remains rather quiet. (Wish we had a microphone buried in the nest so we could hear all of this.) The eyass is quiet for two reasons. First, she has used a lot of energy punching her beak out at the egg, so she tires of all this activity. But more importantly, her lungs are not ready to be exposed quickly to open, dry air.

For most of a month, her lungs have been filled with fluids, and she’s been breathing very moderately through simple air diffusion into her body tissues. But in the last week or so, things start drying out inside the egg and slowly her lungs will get filled with the gases in the end of the shell. It’s still 100% humidity in there, and all is well.

But after pipping, dry air from the outside begins to replace the moist air inside the egg. If that happens too fast because the pipping creates an overly opening, the lungs dry out too rapidly and the eyass simply dies from non-functioning lungs.

So, we must be patient when we see the first pipping. It could be a day or longer before the eyass finally emerges. There is no need for the little hawk to get out of the egg. She’s happy with the humid air in there, while her lungs start to adjust to cold, dry air on the outside.

At the end, when she’s ready, the eyass will make some final thrusts with her head and create an opening big enough from which to emerge. She will hardly be able to hold up her head, and she may not eat or be fed for up to a day. It can be so frustrating to see the little hawk lying down in the nest, without the energy to even stand up and open its mouth for the tiny tidbits of food the formel will offer when the eyass first takes this "I’m hungry" posture.

We just have to wait for all of this to happen. To rush any of this would be to endanger the health of the eyass. In captive breeding of raptors, falconers know that they must never help the little eyass get out of the egg too soon. The eyass instinctively knows what to do, and when to do it. We must merely stand back and watch this marvelous sequence of behaviors.

And we need to continue to thank The Franklin Institute for allowing us to watch all of this. We raptor biologists can never see any of this when aiming our spotting scopes at wild nests. It’s all way up there in a tree, and we can see only the haggards coming and going. Here at the Franklin Institute, everyone gets to look right down inside the nest and see it all. And once again, we should get to see some pipping and then hatching, followed by the formel feeding the newly-emerged downy eyasses.

But I offer a sobering thought, one that we must consider and be gravely ready to confront. As good as these haggards have been, there can be no guarantee that all three eggs will pip, hatch, or have their eyasses grow up and fledge. The stark reality is that one or more eyasses may fail to hatch, or fail to thrive and die. I hope this doesn’t happen. It didn’t last year, so there is an increased chance of full success this year, too.

But eyass deaths are rather common. It’s just part of nature. Should an egg fail to hatch, or a little eyass dies, we must accept this as a natural part of the entire process.

Now, let’s sit back and wait, with our eyes glued to the screen. Let new red-tail eyasses grace the skies of Philadelphia once again!"

–John Blakeman

Saturday, April 17, 2010

Breakfast is Served!

Here's a sample of what the tiercel brought to the nest yesterday to keep his formel content - a baby rabbit, and some greenery. He takes away the remains of the rabbit when she has finished eating. We can also see the brown paper bag which arrived a couple of days ago and that has now been woven into the bowl of the nest under the eggs.

When you see both hawks on the nest the difference in size is quite apparent - the formel is the larger bird.

Thanks again to CamFan for this video footage.

Wednesday, April 14, 2010

Our tiercel is working hard these days!

As the hatching of the eggs gets closer, the tiercel (male) is working increasingly hard to meet the needs of his mate who is doing the majority of the incubation.

John Blakeman shares this fascinating information about how the tiercel and the formel accomplish the tasks necessary to successfully hatch their eggs:

"The smaller tiercel now has his work cut out for him. During incubation, the formel feels tied to her eggs, keeping them warm. She can no longer head out and sit in a tree waiting at length for a prey animal to scurry by. She’s stuck in the nest for perhaps two or three more weeks of marked nest attachment.

Her days of motherly confinement to the immediate nest area will terminate about two weeks or so after hatching, when the eyasses get big enough to stay warm by themselves during the day.
Then, the formel will head off and be absent from the nest for perhaps hours. She will be out hunting like the tiercel, striving to provide ample food for the rapidly growing eyasses.

But for now, the tiercel must now provide food for both himself and his mate. And she’s bigger, too, requiring more food than he does. So his duties are more than doubled.

But he’s a male, and we all know how males like to go out on the hunt. He’s doing this now for his appreciative mate. His testosterone-induced behaviors must now be diverted from nest-building and copulating to a full day’s worth of hunting, killing, and retrieving of prey. Everything depends on him, on his ability to keep his formel sated and seated. If she gets too hungry, she’ll get up off the eggs and in hunger go out and hunt for herself.

But our tiercel was a great provider last year, and will be this year, too.

Then, there is the matter of egg turning during incubation. Before real incubation began, the eggs were left to sit there essentially as they were laid. Now, both parents will feel obligated to stand up a bit, hovering over the eggs, and bend down and push the eggs around the bowl of the nest with their bills. It looks like they are practicing a bad game of soccer with the eggs. Actually, they are causing the eggs to take a new position in the nest. If this isn’t done, the developing tissues and membranes in the egg fuse together and the eyass will die before it can hatch. All bird eggs must be rotated to keep things properly growing inside. So we will see both parents do this. Very important.

One other last thing. It would be romantically comforting to imagine the nest, now that it has a sitting mother with three eggs, as a cozy little nursery cottage, a warm and inviting hawk home, as it were. Not so.

The nest is not the hawk’s "home" in any human-like manner. Their home is the entire square mile or two of the territory they defend, occupy, and hunt in. Regard the nest exactly as they do, as merely an obstetric space, a place to incubate the eggs and raise the eyasses before they are fledged. The nest is not a hawk home, except perhaps to the eyasses for a few weeks before they fledge. Then, it’s just a pile of sticks. None of the hawks fly back and spend the night nostalgically in the vacant nest. It’s not a hawk residence in any such way. The parents never sleep there except to incubate eggs.

For the hawks and us, the adventure continues, now in the new chapter of incubation."

--John Blakeman

Sunday, April 11, 2010

How big are the hawks?

It's hard to get a sense of the size of these hawks from the camera feed. When you see them live, however, you realize how big they are. They are twice the size of a crow.

The formel (female) weighs generally in the range of 1250 to 1350 grams, which is between 44 and 48 ounces. The tiercel (male) probably weighs in the range of 1050 to 1150 grams, between 37 and 41 ounces.

The formel's length, head to tail, is usually about 18 to 20 inches. The tiercel is a bit smaller, from 16 to 18 inches or so.

The extended wingspan of the formel approaches four feet. Thanks to John Blakeman for these hawk facts.

Here are some pictures from last Sunday, kindness of Kay, from inside the Boardroom at the Franklin Institute. Although the trees look fall colored, it was indeed April!

This is the tiercel on the nest.

The following photos show his dark face and bib.

The tiercel left the nest which gave us a chance to closely inspect the eggs....

... before the formel flew in to resume incubation duties.

A close-up of her face clearly shows the pale bib under her beak.

When one is at eye or beak level with these hawks, it is really easy to tell them apart. The camera angle of the Ustream feed gives us a terrific view of what happening on the nest, but makes it a little tough to see their faces when they are sitting on the eggs.

In a couple of weeks, however, all being well when the eggs hatch, we will have ample opportunities to see the hawks together on the nest, as the tiercel brings food in, and we watch them feeding the newly hatched eyasses.