Monday, March 29, 2010

Sunday morning #2 with the hawks

This morning, Kay and I met down at the hawks' nest at 7:30 AM. As usual from the ground looking up, we could see nothing of the sitting hawk except for an occasional beak tip poking above the sticks. We knew that when a shift-change occurred on the eggs, we would know who was incubating, and who was larking around the neighborhood!

Sure enough, at 8:13 AM, the tiercel zoomed in, and they did their now smooth-as-clockwork exchange.

The tiercel had barely landed when he was already at the back of the nest getting ready to settle in on the eggs, while his mate stepped to the front and decided which route she'd take to go get breakfast.


It took her all of 2 seconds to ponder the direction, and then she was off! She flew rapidly towards the Central Branch of the Free Library.

























She then flew sharply downwards out of sight, and immediately there was an explosion of pigeons frantically flying up and away from the breakfast predator. We could not see whether she caught anything, but given the 50-60 pigeons that burst up from the ground, the odds are good that she successfully grabbed the slowest, most vulnerable bird.

We walked the three blocks or so over to where the pigeons had been, and saw that someone had spread many doughnut holes and bread crusts on the ground which had obviously attracted the large number of scavenging pigeons. Once again, we had witnessed the hawk's uncanny ability to locate potential prey from a great distance.

We returned to the nest, all the while watching for the return of the formel to resume incubation duties after her breakfast break. And we waited.... and we waited.... 9:00 AM.... 9:30 AM.... 10:00 AM.... 10:30 AM.... Where was she? Had she somehow slipped back onto the nest without our noticing? It's hard to miss a red-tail hawk!

I had my laptop with me, but could not pick up the Franklin Institute's wireless signal to access the camera feed to see if we could tell who was on the nest, so I walked around and into the Franklin Institute's lobby, leaving Kay on patrol at the nest.

When I pulled up the camera feed, I was startled to see that the hawk on the nest was the formel. How had she and the tiercel switched places? I asked the viewers - via the chat feed - whether anyone had seen the hawks change places in the last 15-20 minutes. I was assured that this was most definitely the formel, and no-one had seen a hawk fly in.

I felt like a child in the presence of excellent magicians - "How did you two hawks do that trick?"

Here are some of the comments from that conversation:

Sunnydixie: yet this bird has the wing marks like the female -- however the head looks stripier than the female. Her head color is more blended.

Sunnydixie: I'm REALLY confused now....

Mmggolfer: just like the pix I sent you the other day - no question in my mind that it's mom unless I was wrong to begin with.

Mmggolfer: Besides, too calm to be dad - he would have taken off a long time ago :)

Winksmom: I'm pretty sure it's Mom sweet soft face white bib and sitting like she's happy to do so. I think it's Mom, Della.

Char8582: Hello all:)

Char8582: Has Mom been away long?

Char8582: Oh I see this is Mom...looks like Dad to me!

Char8582: Did they just switch??

CatzeePA: G'mornin..Mom just preened and stretched and changed positions

Char8582: I got up for a minute and thought they switched!

Mmggolfer: Still mom - just watching the world go by - stood up, checked out her eggs, and sat down again.


Meanwhile, back at the nest, the sitting hawk had stood up, leaned over to turn the eggs, and then had turned around to look out, and Kay had taken its picture.


It was the tiercel with his unmistakeable brown bib!

Kay zipped around to join me inside the Franklin Institute, and confirmed that no hawk had flown to the nest. We looked at the picture she had just taken, and then looked at the camera feed, and by the feather markings on the wings and tail, and what we could see of the hawk's face, and by everything we knew about ID'ing these birds on the camera feed, the bird on the nest seemed to be the formel, yet the picture Kay had just taken was of the tiercel. What was going on?

With nothing to be gained by continuing to watch my laptop screen, we went back out onto the street, and no sooner had we turned the corner and could see the nest, but a hawk flew in. So we were pretty certain we had both hawks on the nest. Almost immediately, as is their routine, the sitting hawk flew out and it was definitely the tiercel, leaving the newly arrived formel on the nest.


So, the bird that we had all been so sure was the formel sitting on the nest, was in fact the tiercel, and the formel had indeed been away from the nest for over three and a half hours. The tiercel had done a super good job of patiently staying on the eggs, only getting up once that we saw to stretch, turn around and move the eggs.

He flew over us almost directly overhead, and we could easily see his dark bib under the beak.....

..... the beautiful symmetry of his plumage.....


.... and that gorgeous red tail.


He headed across the Ben Franklin Parkway to his usual perch in the trees alongside the Barnes Museum construction site (formerly The Meadow), but before he landed, he showed off his phenomenal flying skills, zipping through and around the branches....

.... before settling in his chosen tree to recover from his marathon egg-tending session.

So even though it is really easy to tell the difference between the male and the female hawks when they are in flight, or when they are both on the nest, we learned today that when looking down at a single hawk on the nest from the camera feed, it is very easy to confuse one for the other.

John Blakeman offered the following observation about the feathers on the hawks' heads:

"Here's a quick screen grab of both birds. The tiercel, with his slightly streaked, mottled head feathers is on the left. The formel's head feathers are much more uniform, on the right."

Good luck, hawk watchers!

Wednesday, March 24, 2010

Why did the formel attack the escaped cage bird?

Sunday's blog entry detailed the formel's dramatic and gory capture of an escaped cage bird. Because she is now in full incubation mode, and mostly relies on her mate to bring her food, I asked John Blakeman whether she had to hunt because the tiercel wasn't keeping her sufficiently supplied with food, or whether it took a few days for the "Stay on the eggs all the time" mode to switch on for her after the third egg was laid.

Here is his fascinating reply. Who knew that there is a No-Kill Zone around the nest?



From John:

Here are some important understandings of the formel's capture of the escaped cage bird, whatever it might have been.




First, she quickly spotted the bird because it flew or acted in a manner the formel had never seen. Red-tails are always looking for or noting anything different in their territory, especially any small potential prey item.

In this case, the bird probably fluttered its wings in such a manner that it appeared at a disadvantage. As some sort of tropical bird, it may have been at a thermal disadvantage in Philadelphia in March. It may have been quivering to stay warm. Even from three blocks away, the hawk would have seen that instantly and recognized the bird's vulnerability.

The formel nailed this non-native bird for reasons entirely unrelated to the tiercel. She had been sitting in the tree for a long time, and was able to take a break from the nest to preen, to slice (defecate), stretch, and otherwise make herself comfortable for a time in her more usual posture.

But when she saw the small bird, she was instantly after it. Couldn't resist.

Note that the captured bird was some distance away. This is important. We know that nesting red-tails and other raptors have an interesting response to prey when sitting on eggs or tending to hatched eyasses. The adults' hunting and killing impulses are markedly suppressed within a certain radius of the nest. I've seen house sparrows nesting inside the sticks of a large, well-used and active red-tail nest. The haggards pay no attention to these otherwise fine prey birds, although they could easily jamb a foot down into the sparrow nest and pull out a fistful of baby sparrows.

That's because if they attacked them, or any other prey animal near the nest, they could also in an unguarded, impulsive instant just reach out and kill a downy eyass. For those of us who have watched falconry red-tails kill game, we always marvel at the restraint of the haggards' normal killing impulses at the nest. If they found a similar downy bird on a nest elsewhere, they would pounce instantly on it.

Pale Male and all of the New York City nesting red-tails have learned to visually scrutinize the walls of Manhattan buildings, looking for pigeons nests on window sills and building ledges. They take nestling squabs (baby pigeons) with ease, delight, and with no restraint. A pigeon squab at the start doesn't look much different from a newly-hatched eyass.

Around the nest, within a few hundred yards or so (it varies greatly from nest to nest), prey animals are safe. There is a respected no-kill zone around each nest. Rats and mice and pigeons within this zone will not be preyed upon during the nesting season, so as to never harm an eyass, who would make as fine a meal as any other prey animal.

In this case, our formel saw a vulnerable bird far outside the no-kill zone, and she shot out and took it. Even though she's spending most of her hours sitting on three eggs and keeping them warm, she's still looking out over the landscape next to her nest and is watching all the animals and activities out there. When given a chance, when an animal is seen to be both beyond the no-kill zone and vulnerable, and when she's able to get up off the eggs because the tiercel takes his brief turn on them, she'll be on the attack. After all, she's a hawk, an avian predator of the highest order. She lives by hunting and killing. When prey is seen and the opportunity arises, she will make a kill."

--John Blakeman

Sunday, March 21, 2010

Sunday morning with the hawks

On a gorgeous Sunday morning, a group of hawkaholics met at the nest to spend a couple of hours in the early morning sun observing the hawks. Kay Meng took these amazing pictures.

For over an hour, we saw nothing. We assumed the formel was on the nest, but from the ground she remained invisible. Our waiting eventually paid off when the tiercel flew in.


The formel immediately stood up, and it was clear that she was ready for a shift change!


As the tiercel started to settle himself on the eggs, she looked around as if to say, "I'm outta here!" and then she was!


Outta here indeed!

She flew into a nearby tree and preened in the sun, while her mate got himself organized with the eggs.


We turned our attention back to the formel just in time to see her launch into the air, and fly swiftly about three city blocks' distance toward the Central Branch of the Free Library. Just as it seemed she would crash into the side of the building, she dipped down, grabbed something from the bushes alongside the Library, and then flew sharply upwards to perch with her prey on an upper ledge. She mantled over it briefly, then flew to the top of a nearby telegraph pole. It was truly amazing to witness the acuity of her eyesight that allowed her to spy and zoom right in on a small bird from such a distance.

We dodged traffic on the Ben Franklin Parkway and raced toward the Library expecting to see her tearing into a pigeon. Much to our surprise, it appeared that the smallish white bird with the gray/blue belly she had captured had a beak much more like a cockatiel or parakeet than a pigeon.


She started ripping off the feathers, and they came down in a cloud around us as we looked up.


For a moment, it looked as if she were going to try to swallow the bird whole.


Then another surprise - when she opened her beak and the dead bird reappeared, minus its head - there was visible a band on the left leg of the bird, just above its claws. Was this unfortunate little bird an escaped pet, or had it once belonged in a zoo?


The formel then flew swiftly back with her headless prey to the nest.


The tiercel was more than ready to end his egg-tending duties, and he left the formel to her breakfast on the nest, while he flew up to a wide ledge at the top of Franklin Institute. He then stepped back a few paces and disappeared, leading us to think that the ledge must slope backwards.

Our theory proved correct when he reappeared, soaking wet! There must have been a pool of water captured in the sloped angle between ledge and wall in which the tiercel bathed.


He shook vigorously a few times, spraying water drops in the sunshine, and widely stretching open his beak in what appeared to be a silent expression of pleasure.....


... or perhaps it was just a yawn of paternal contentment after a busy six days of watching his next brood's eggs appear.


He sat on his sunny ledge a while longer, then flew to the same tree earlier occupied by the formel, and caught up on his feather preening.


We left as he launched off towards the Library, presumably to do some hunting for himself, or maybe find an early lunch for the formel.



So, in the space of a couple of hours this morning, we were privileged to have a ring-side seat for some of the hawks' daily routines invisible from the nest camera.

Just an extraordinary Sunday morning.

Saturday, March 20, 2010

Incubating the eggs: everything you need to know


Each day we have new questions about what we're seeing on the nest. After yesterday's excitement with the arrival of the third egg, we now wonder what will happen next. Will there be a fourth egg, or will incubation begin?

It is highly unlikely that there will be a fourth egg. The usual egg count is almost always two or three. John Blakeman has sent us below all we need to know about the next stage - incubation - when the formel will be spending hours at a time on her eggs.



John Blakeman tells us:

"The laying of the third egg will initiate sincere, authentic developmental incubation. Until now, the formel has been sitting loosely on the eggs. She has merely kept them slightly warm, not the prolonged and enduring 100 degrees F (or so) temperature needed for incubation.

Until now, sitting has been merely maintenance. The embryo of the first egg has not developed much, if at all. A fertile egg kept at the start between 40, 50, or 60 degrees or so simply just sits there, viable and alive, but with no growth of the organism inside.

At this point the baby hawk, which is called an eyass (EYE-ess) not a "chick" by those who know raptors, is only a mass of undifferentiated cells in the blastodisc on the surface of the yolk.

With proper incubation now beginning at consistent warm egg temperatures, the blastodisc cells will begin to grow, using the lipids in the yolk for energy, and the proteins and minerals in the egg white as building materials for the new tissues and organs.

The egg, or at least the developing embryo, will now start to metabolize, to take in and use oxygen and give off and expel carbon dioxide. Of course, the egg and developing embryo have no functioning lungs or other structures to accomplish these gas exchange processes. Oxygen goes in and carbon dioxide comes out of the egg through the shell, which on a microscopic level is rather porous.

In the next 28 days or so the egg will actually lose weight, as water evaporates out through the shell. The rate of this water loss is important and can signal the rate of development of the embryo and eyass inside. Rapid loss of water will kill the egg, and no loss of water would indicate that the embryo is already dead. The moist skin of the formel’s brood patch (bare skin on her lower chest/belly area) will help to control the moisture in the egg.

But these should not be concerns. This is an experienced, successful pair of red-tailed hawks who incubated, fed, and fledged three eyasses last year. They’ve done this before and know what to do, so we needn’t be concerned.

Here are some things to look for, and one thing not to be concerned about.

First, only the formel has a distinct, naked brood patch under her chest and belly feathers. The tiercel retains his downy feathers, so when he sits to incubate during the times the formel gets up, stretches, preens, defecates, and otherwise attends to herself, the eggs cannot be kept quite as warm as when they are in direct contact with the formel’s naked brood patch skin. This is one reason the formel does most (but not all) of the incubation. She’s just much better equipped, both physically and mentally, for this important job.

And to do that, watch now how she settles on the eggs. Until the third egg was laid, she and her tiercel just sort of plopped down gently on the eggs. Now, once she realizes that another will not be coming (red-tails in the Midwest and East virtually never produce four eggs), she will be much more diligent in settling upon them. She will sink a bit more slowly, and will often gently rock back and forth to position the eggs right up against her brood patch.

I have to think that this is a profoundly satisfying and rewarding feeling for the mother, to have those eggs right against her body. After she’s been away and resumes incubation from her colder mate, I’m sure she feels the slightly cooler egg temperatures. It must be gratifying for her to get them all cozy once again.

And that’s the second thing observers will note. From time to time, the eggs will be left unattended out in the cold air, often for 10 to 20 minutes or more. We’ve seen this already, many times. But true incubation hadn’t started yet, so there was no problem. Now, with development of the embryo in the blastodisc, an overly long period of cooler temperatures will kill the eyass.

All of us who have watched red-tail nests have been really anxious about these long, egg-cooling intervals. But in virtually every case, except with first-year or inexperienced adults who do often fail to keep the eggs warm enough, experienced adults like these know just when to get back on the cooling eggs and resume real incubation.


Why, then, do the parents allow these unattended, periodic cooling periods? We don’t know. I speculate that it may have something to do with oxygen diffusion and absorption into the liquid tissues of the egg and embryo. As you might have recalled from high school chemistry, the warmer a liquid is, the less gas remains dissolved in it. You didn’t drink that warmed-up soda after the carbon dioxide diffused away from it as the soda got too warm.

So, it’s possible that once a day or so the parents allow the egg to cool a few degrees for 10 or 20 minutes, allowing more oxygen to diffuse through the shell and become dissolved in the egg fluids. A breath of fresh air, as it were, for the developing eyasses.

Or, perhaps it just doesn’t make any difference with the oxygen, and the egg grows well enough with these periodic uncovered periods.

Either way, don’t be concerned until the egg remains uncovered for 45 to 60 minutes or so."

--John Blakeman

Friday, March 19, 2010

Arrival of the Third Egg

Here's edited video footage of the formel laying her third egg this morning somewhere between 10:00-11:00 AM EDT.

Many thanks again to CamFan in Oklahoma for editing and sending this invaluable resource. (Note that the time counter in the corner reflects CDT)

BREAKING NEWS - Third Egg Arrrives!!!!!

The third egg arrived on Friday, March 19 at about 11:00 am EST.
Let the hatching begin......

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

Tuesday, March 16, 2010

Late-breaking news: 2nd egg arrives!

The second egg appeared this morning at around 10:15 AM.

This screen shot was taken at 1:15 PM, and because the sun is finally shining in Philadelphia, there is some sun-glare.

How much sex for another egg?

I wonder how many work hours were lost yesterday as we anxiously watched the nest for the appearance of a second egg?

Though the single egg was faithfully attended by a parent hawk most of the time, there were periods yesterday when neither hawk was on the nest, and then observers on the ground reported seeing them copulating. The question then asked was "Does each egg have to be fertilized and then it will be laid?"

At the rate our happy hawks have been observed "doing the deed" the nest would by now be overflowing with eggs!

John Blakeman gives us another chapter of hawk knowledge:

"No, a single copulation event is enough to supply sufficient sperm to impregnate all the eggs, one, two, or three. Many falcons for falconry are captivity bred with artificial insemination, and a single introduction of semen into the falcon's cloaca is usually sufficient.

But let's face it. Red-tails like to have sex. They do it frequently, from late January (or earlier) all the way through the breeding season. Some birds even copulate in June, right in the view of the new eyasses (Have they no shame?)!

That, of course raises the question of the neural responses (well, let's be plain, the eroticism) of the birds. In this venue I won't speculate too deeply (Is that the word?) about this matter. But I don't think it's much like human or mammalian sex. Still, the hawks like to have sex. They like the amorous preliminaries, the stooping flights (which aren't always necessary) and the come-hither bowing of the formel, etc.

As with humans, the sex act is a significant and reinforcing factor of the pair bond. I find it hard to convey the significance of this, how each bird so calmly, even lovingly, in a hawk-like way, so easily tolerates his or her mate. This is not the basic nature of these birds. They are independent, isolated, and otherwise self-sufficient. Except for breeding, they have no need or interest in social interactions with other red-tails. Only in this pair-bond arrangement do these things so wonderfully happen, and at the Franklin Institute we get to see them so intimately. Just great.

It's about 4:00 PM EDT [on Monday March 15]. I've been watching the formel sitting now for some time. I think she's getting ready to lay once again. The time is right, and she's a bit calmer."

--John Blakeman

However, as twilight arrived on another gray, wet, windy day in Philadelphia, there was no second egg. After sitting on the nest for over two hours, the formel stood up and then flew off the nest, and the egg was left alone as darkness fell.

Perhaps today......

Monday, March 15, 2010

Day 2 of The Egg

Here are the first close-up views of the egg, kindness of Gene Mancini, the hawks' Godfather at the Franklin Institute.


You can definitely see the mixed stream recycling the hawks have going with their newspaper and plastic!















Early this morning (Sunday), Kay Meng and I decided to meet down at the nest to check out what was happening. Forgetting about the clocks switching forward, it was almost total darkness when I arrived outside the Franklin Institute at 6:30 AM, but there was just enough light to see a hawk up on a lamp pole about 50 feet from the nest.

On seeing me and Kay, he (as we later determined) flew immediately to the nest with a couple of indignant squawks, and settled down on the egg. No other bird was on the nest, so we realized the egg had been alone, with the male watching it from close by.

After ten minutes or so, the tiercel stood up, leaned forward and picked up a dead mouse that had evidently been left in the nest as a snack. He started eating it, then the formel arrived with her own mouse, and the tiercel left after a couple of minutes.

In the space of the next couple of hours, we saw the male and female come and go from the nest several times, and despite the appallingly stormy weather of the previous 24 hours, and the continuing rain, they seemed to be having no trouble finding fresh food.

We noticed that there is now a screen in the Boardroom behind the nest. Here's what it looks like from inside. (Gene's pic)


Yesterday evening, Susan Holmes, the Senior Museum Educator at the Franklin Institute sent me this observation after checking on the hawks late afternoon:

"... it’s 4:40 pm and I just went down to look at the hawk from the darkness of the boardroom... He/she is sitting there a little damp and fluffed up, but out of the wind ... and looks quite contented, watching the goings-on in the street below and chirrupping (sp?) quietly to him/herself."

This gives you an idea of what Gene saw through the rainy Boardroom window at noon today - getting up close with the formel.

Who's watching whom?

The building in the background is the main branch of the Free Library.

The outdoor camera gives a different angle on the nest, and this shows, as John Blakeman suggested, that the hawk is not really nestling down on the egg as much as just leaning over it to keep it protected from the elements.


A final view from today (Sunday) comes from the Ustream camera which we have all been watching avidly. This is the tiercel, rather anxiously looking out from the nest, after sitting on the egg for a while.

He seems less willing than the formel to stay for long periods with the egg. A moment after I took this screen shot, he was gone!

Saturday, March 13, 2010

The Arrival of the First Egg

On a stormy wet day in Philadelphia, the Franklin Institute formel laid her first egg. If you missed the actual moment, here is the Ustream camera footage, kindly edited and sent to me by CamFan in Oklahoma. Following this video clip are some images from today.



The morning began with a very wet hawk sitting on the nest. With the rain darkening their feathers and the camera angle, it was difficult to tell whether it was the formel or the tiercel, but we think it was the tiercel (male).


A little later, the formel was on the nest, along with the remains of breakfast lying on the front nest rim.



Then around noon came the news that an egg had been sighted. Here is the formel covering her egg at 12:20 PM.


The tiercel returned to the nest, and then the moment we had been waiting for - the egg!





EGG!!!! (Updated)




In the midst of the vicious wind and rain storm currently battering Philadelphia, the formel laid her first egg around noon today. Here she is sitting on her egg at 12:30PM.

John Blakeman has been watching the camera feed and comments:

"Couldn't see the egg, but the behavior sure was persistent and different.

I doubt that this is the tiercel. I think it has to be the formel on the nest. The tiercel just doesn't have the sitting motivation like the formel after she's laid an egg.

And notice that as I predicted, the bird is not jostling down and sitting tight on the egg. She's just keeping it covered, not really incubating yet. That'll start when the last egg is laid.

Could be only two eggs this year, because of the persisting snow and difficulty killing enough food during the snow.

Someone noted that the sitting haggard this morning (Sat., 13 March) looked a bit ragged.

That's because of the rains the previous night. I've explained earlier that the hawks spend a lot of time preening, distributing water-repelling oil from the oil gland on the rump to all the feathers of the body. Yet, in a soaking downpour, rain still penetrates some of the outer body feathers, and they tend to clump up in their soggy condition.

This is what made the haggard look "ratty." The downy insulating feathers beneath remain dry and warm. But for a while, the bird can look a bit disheveled. But it's quite normal, something the hawks deal with in heavy or persisting rains."

-- John Blakeman

Wednesday, March 10, 2010

Why do the hawks bring evergreen sprigs to the nest?

The nest has been growing steadily as the hawks bring sticks, leaves and twigs on a daily, even hourly basis. The Ustream live camera feed allows us to watch every detail of the hawks' attentive nest-building. We've been struck by the number of evergreen sprigs and fronds that they are weaving around the edge of the nest.

This afternoon, we also saw some free advertizing for City Paper!

John Blakeman offers some perspective on the significance of the evergreens in the nest:

"Nest watchers have noted that the haggards bring sprigs of evergreens into the nest. Almost all red-tails do this, for really unknown reasons.


The conventional explanation is that these pine or spruce twigs have fragrant volatile chemicals that drive off feather parasites. Indeed, such vapors do emanate from evergreens, and there must be a few bugs at a nest with evergreen sprigs. And yes, red-tails can have small populations of tiny feather lice. But these are seldom seen, and cause no health or feather problems in healthy birds. I have never been able to discover any of these on my falconry red-tails.

So repelling arthropod (bug) parasites is not really a factor.

And in fact, just look at where the haggards place the evergreen sprigs. If they are brought to the nest to drive out feather bugs, they aren’t in the right place. Most of them get placed out on the rim surface, where the birds stand, not where they squat. The aromatic vapors from these can’t effectively penetrate through the feathers to the birds’ skin surfaces, where the feather lice (what few there are) reside.

Frankly, the birds themselves keep the feather bugs in control by their frequent and prolonged preening. Nest watchers will see a lot of this, with a bird just standing there with its head turned around and probing through feathers all over its body.

This does two things. Mostly it distributes oil that the bird strokes off by touching its beak to the oil gland on the rump, beneath the feathers there. Then she strokes her beak through her feathers, getting a microscopic layer of this rain-repelling oil all over her body. Like a duck, water generally runs right off the hawk’s back, because of this oil.

Think of that when our formel will be sitting out there in cold March rains, keeping her two or three (we hope) eggs warm and dry. Periodic preening is crucial for this.

But the evergreen sprigs? They can’t be there to repel bugs. Wrong placement.

I really think they’re just really decoration, making things a bit more pretty (well, chromatically luminous for my academic colleagues) than just the bare sticks. I also think it behaviorally conveys commitment by the birds both to the nest and to each other. I don’t think unpaired red-tails ever carry around or do anything with evergreen sprigs.

For fun, I’ve tossed a few of these into my falconry red-tail’s chamber in March, and she does absolutely nothing with them. She pays no attention. It’s obviously a nesting and perhaps a pair-bond thing.

"Here, I brought you this. It shows I love you, and I like our nesting pad here. Don’t we got it good?"


And yes, my academic colleagues will cringe, as I internally do when I present such anthropomorphisms. No, red-tails don’t converse or even think lubby-dubby thoughts. It would be an error to explain what we are seeing in such thoroughly human or mammalian terms. Biologically, it’s not so clearly parallel.

But on the other hand, there are distinct behavioral parallels, although they are not neurologically exact. Hawk brain structure is very different from ours, and they can’t think too deeply on much of anything. Their behaviors are rather ritualistic, just going through the motions, as it were. Their brains aren’t big enough for much more than this.

But that should not discount all the wonderful behaviors we are privileged to watch. It can’t be denied that this is a committed, reproducing couple, tending diligently to bring a new generation of their offspring successfully into the Philadelphia skies.

Everyone can decide for themselves how these behaviors originate. If some wish to assign entirely human traits to these, so be it. It can be fun, and perhaps some children’s literature could derive from what will be seen. On the other end of the spectrum we are cold-hearted scientists, attempting to explain everything in quantitative metrics, and genetic and bio-chemical mechanisms.

But wait! I’m a scientist. But really, those are NOT the reasons I’m watching all of this. I’m as addicted to watching all of this as everyone else. I’m doing this because it’s just so profoundly exciting and fun, to be able go right in the living room and neighborhood of this bird family. We get to see it live and in person. How exciting, for each and all.

Once again, nothing like it in all the world."

–John Blakeman



As I read John's comments about the evergreens, I remembered Barbra Streisand's hit song of a few years ago entitled "Evergreen," and the final stanza of those lyrics does resonate with the commitment of the Franklin hawks to each other:


Two lives that shine as one
Morning glory and midnight sun
Time we've learned to sail above
Time won't change the meaning of one love
Ageless and ever evergreen

Tuesday, March 9, 2010

When will the eggs arrive?

"When will the eggs come?" is the question now on all hawkwatchers' minds.

John Blakeman has been watching the haggards' activity on the nest via the Ustream camera feed, and offers us these comments:

"I note that a number of posters are wondering when the eggs will be laid. Who knows? But from what I saw today, it's not likely to be right away, perhaps in a few days or so. (But again, who knows? I'm often fooled by these birds.)

Here's one thing that viewers can watch for. The formel, when the big egg really starts to form and descend down her one fallopian tube (mammals have two of these; birds have one, so that they don't have to fly around with un-used extra weight), the hawk will take on a somewhat stiff and concerned "look." She will not be as active and will just sit there for long periods, looking a bit dazed.

And if I had a fallopian tube with a descending mass commensurately as big as the hawk's egg, I'd be dazed, too.

Then, she'll sit down in the nest and get ready. The laying of the egg can't been seen. It just comes out, without much effort. But she'll get up a bit later, turn around, look at it, and then sit back down. That's probably when we'll see that the first egg has been laid.

But serious incubation won't start yet. That happens when the formel knows she's laid the last one. Then, it's serious incubation time. Keep those eggs warm and rotated. She will now sink lower into the nest, and jostle herself back forth, getting the new eggs tucked right up to her naked brood patch, a bare area under the chest feathers. That will keep them warm.

The fun then begins for all of us. Here's awatchin'."

–John Blakeman

Monday, March 8, 2010

Our hawks were on TV tonight!

This evening, our local ABC news affiliate - Action News 6 - here in Philadelphia ran a story on our hawks. Very cool to see the interior of the Boardroom and the window that looks out onto the nest.

The hawks seemed completely unfazed by the TV cameras, much to the surprise of Matt O'Donnell, the reporter. He might have heard the following exchange between the haggards:

"Look, honey, more cameras!"
"Camera, schamera - seen one, seen 'em all."

Click on this link to view the Action News 6 segment.

Keep your eye on the hawks at the Franklin Institute


Thursday, March 4, 2010

The scream of a red-tail hawk

John Blakeman has told us that if the hawks were threatened by the presence of humans around their nest, they might scream. The scream of red-tail hawk is unmistakeable! The red-tail in this clip is eating a quail on the fist of its falconry trainer.

John Blakeman commented on this video clip:

"This is a classic red-tail scream. Unfortunately, the bird looks a bit scruffy, probably an artifact of low-res video and You-tube.

More objectionable to me, however, is the bird's deportment. It thinks something or someone is about to take its food or enter its personal space. It has its hackles up (feathers on the back of its head), in a very threatening manner. To me, this looks to be something of a "marhawk," another of those falconry terms that have come down to us from Middle English or Elizabethan times.

A marhawk is a raptor that has been captured for falconry often as an eyass, and has been poorly "manned," tamed, or accommodated to its otherwise new good life in the falconer's care. A poorly manned hawk, especially when taken as an eyass, or trapped in summer, while it is still otherwise in the care or feeding of its parents, easily becomes defensive, as this bird does.

The hawks belonging to me and my falconry apprentices never, ever scream on the fist. Nor do they ever raise their hackles (feathers on the back of the head) in a display of threat or anger. Our birds are like the haggards being watched at the Franklin Institute, calm and regal, in utter control of themselves.

Still, this YouTube scream is authentic and representative. Red-tails don't have much of a vocabulary, and most people hear only the scream. When uttered from 500 ft above the Franklin Institute, or above one of my rural Ohio woodlots, it's a piercing (but not loud) aural highlight that connotes wildness and nobility. It sends a spike of excitement up my spine every time I hear it, whether on a grainy YouTube segment, or better, when it's heard live from above.

As always with red-tails, nothing like it in all the world."

-- John Blakeman

Wednesday, March 3, 2010

Does activity in the window bother the hawks?

As we know from watching the live camera feed of the hawks on their window ledge outside the Boardroom of the Franklin Institute, there are times when we can see reflections in the glass of activity in that Boardroom. Some viewers recently expressed concern that the proximity of people and their activity might stress or startle the hawks:

"Does anyone know if the hawk's view inside the Franklin Institute window is blocked? I've been concerned that all the activity in there--people with cell phone cameras and other photo equipment right next to the window will cause them to abandon the nest." "One of the most fundamental lessons that I have learned about bird watching is to be discreet, quiet and respectful...I have to wonder if cell phone flash or people viewing them through the window could become disturbing to these hawks."

Gene Mancini from the Franklin Institute who oversees the welfare of the hawks, responded, "The view into the Boardroom is not blocked. I can tell you from observation that the hawks show absolutely no signs of stress at the goings on in the Boardroom. They spend quite a bit of time watching the people as they convene or move about, and do not balk at someone walking right up to them.... initially we were very cautious, but the hawks clearly were looking in to see if there was any activity. I am not aware of anyone using a flash to take photos. And let me assure you, the Boardroom at the Franklin Institute is visited by the smallest of circles... everyone knows the rules. This is our second season with these birds, and one of the premier hawk experts in the nation says our pair is in spectacular shape."

John Blakeman adds this perspective:

"
These are seemingly legitimate concerns, that close-up views behind the window might disrupt normal nesting activities. I, too, last year pondered this.

But the record is very clear. The hawks pay virtually no attention to humans behind the window. And this relates to humans everywhere in the nesting area. After watching dozens of wild, rural red-tail nests, I still marvel at how this pair utterly disregards nearby humans. Just the other day I saw one of the haggards sitting on the edge of the nest, looking around. And right there on the corner below was a person crossing the street, heading right toward immediate nest area.


Had that occurred at wild or rural site (these birds really are "wild," utterly unconfined in any way, originating in the wild somewhere), the hawk would have been instantly off the nest. She would have screamed at the intruder, and leapt into the sky, circling in ever higher rings around the guy. His presence would surely have been disruptive, and the hawk would have responded with alarm.

In this case of the Franklin Institute hawk, the hawk paid no more attention to the pedestrian below than a rural hawk pays to a grazing deer or cow -- no concern whatsoever.

But would this accommodation then extend to gawking humans behind the window (and we all gawk when we get to see these birds so closely -- so lucky we are)? Very clearly the birds do accommodate, and this has occurred in other areas. I have reports from several people around the country, in urban areas, where red-tails have landed on building window perches and looked right into human living spaces with curiosity, not alarm. They sit there at length, watching both the humans inside and the landscapes on the outside. Clearly, the hawks understand that the humans inside are restrained by the window. To them, it seems to appear that the humans are strange animals that can walk around inside cliffside rocks. And they never come out of those rocks, either. The hawks on the nest show no concern whatsoever. They probably think we are really weird, trying to live inside rock cliffs.

Now if someone were to come up to the Franklin Institute window and start banging on it, flapping their arms ("Those humans have such weak wings,") the hawks might start to pay attention, probably with a mere look of incredulity. I would of course recommend, as I'm sure the Institute does, too, that no one press their noses or hands against the window pane.

This contrasts markedly with how the hawks respond when one of us raptor researchers climbs up a tree and tries to peer into a wild rural nest. Very different. The hawks will scream, and when close can actually attack. Usually, they do jump off the nest, but circle closely above, trying to divert us. Rural hawks also just don't accommodate people walking around the ground under their nests, either. But here, we must follow the leads of the resident Franklin Institute pair. They've got it all figured out.

Oh, and what about someone taking some flash photos through the window? Well, the flash has no more effect on the hawks than lightning. I've taken hundreds of close-up flash photos of my falconry and research hawks, always without any reaction or concerns by the birds. They are oblivious to it. It's not a concern at all.

--John Blakeman

Tuesday, March 2, 2010

Sex, Hawks and Rock & Roll!

Yesterday evening, at 7:53 PM, hawkaholics everywhere were riveted by this post from Weaselm on the Ustream chat line:

"Hey Everyone - Big exciting news! A friend, biking home
from work at around 5:30 PM, heard a hawk call, looked up and saw two red-tails on the corner of the FI and they started mating!!"

Immediately, the questions - discreet and otherwise - started flying, and roughly in these categories: how, where, when and how often.

So, as always in times of hawk ignorance, I turned to John Blakeman for his wisdom about the sex lives of hawks.


John writes, "It was pleasing to learn that the haggards were 'mating.' But that's not so, in a proper way. The two haggards -- properly -- mated when they came together, started to defend their territory, and began building a nest last year. They mated last December or January (or before). Mating is the social process where two birds decide to share a territory and cooperate in defending that territory, and then build a nest and attempt to produce offspring. Mating is a long-term social process, similar to 'marriage.'

None of this should be confused with what is properly called copulation, sexual transfer of sperm from the tiercel to the cloaca (genital opening) of the formel. Just as human marriage is seldom confused with human sex, hawk mating should not be confused or confined only to copulation.

Frankly, red-tails copulate frequently, many times a day. Copulation is quick, usually about seven seconds.

And copulation is often (but not always) preceded by a series of stupendous dives by the tiercel from a good height down to the circling formel below. Hawkwatchers at this time of the year should be looking above for the haggards soaring in circles. The first amorous signal is the dangling of legs while soaring. This is profoundly sexual.

Then, the tiercel soars to a good height and folds his wings and plunges at well over 100 mph straight at his aroused formel below. Just as he's about to strike her on his rapid plunge (properly called a 'stoop'), the formel turns her wings sideways and allows the tiercel to shoot through her immediate airspace without hitting her.

After dropping beneath the formel, the tiercel throws out his wings and the large G-forces divert his momentum back into the sky. This giant aerial U-shaped flight is one of the most exciting of any bird, matching the lethal prey-killing stoop of a peregrine falcon.
But red-tail love stoops often happen without anyone taking note. Too often, we look for red-tails on buildings in urban areas, and on trees and poles in rural areas. Of course, that's where they spend their time most of the year. But in January, February, and March, we need also to look up into the sky for them.

After the love stoop, the formel then lands on a tall limb or building edge. She leans over in a low horizontal posture, whereupon the tiercel gently lands on her back and grips her between his feet. He wraps his tail back under and around the formel's diverted tail, thereby aligning his cloaca with hers. And in a few seconds, sperm is transferred.

He jumps down off his mate, and both birds often 'rouse,' shaking and rearranging their feathers. Hawks rouse only when they feel good - and after sex, they do, and they commonly rouse.

So, from now on, when the Franklin Institute red-tails are seen to be 'mating,' they aren't. That happened last year, and the birds have been mated since then. But now, in the breeding season, they are copulating many times a day.

For our tiercel and formel, life is good.

Eggs should be forthcoming any time from the second through the third week in March. It could be earlier, or later, but the middle two weeks in March are typical for red-tails at the southern Pennsylvania latitude. In my area, here in northern Ohio near Lake Erie, our birds are about a week later; but they, too, can vary by a week or two.

So, I've suggested the use of three new terms. The birds 'rouse' (pronounced ROUW-ze, rhyming with 'arouse') when they shake their feathers and rearrange them. When they 'mate,' they are really copulating - conducting outright and purely visible and profligate sex. In Philadelphia, no less.

And when the tiercel folds his wings and plunges at great speed toward his formel, or sometimes just when she's sitting, he's performed a stoop, a stunning aerial plunge. Because it's such fun, formels will also tip over and do a stoop, too.

Nothing like it in all the world." -- John A. Blakeman


(Note to self: Think I might like to come back as a hawk....!)


Monday, March 1, 2010

Telling the difference between Mom and Dad

As we watch the increasingly busy activity at the nest, perhaps the most frequent questions are, "Is that Mom?", "Is that Dad?", and "Which is which?"

John Blakeman, our Ohio expert on all things hawk, encouraged us last year to use the correct terminology for the hawks. John is a licensed Master Falconer, a former federal bander of raptors, and also an advisor to Marie Winn and others in New York regarding Pale Male and his nesting exploits there.

John told us, "The male, the father, is the 'tiercel,' pronounced 'TEAR-cel.' He's a bit smaller than his mate. A female hawk is properly called a 'formel.' The parents - the tiercel and the formel - as full adults are properly said to be 'haggards.' In the case of hawks, a haggard is not a scruffy, raggedy old individual. Quite the opposite. A haggard hawk is a full adult, thereby possessing all the knowledge and experiences needed to survive. The 'babies' are neither 'chicks' nor 'babies.' Chicks are little chickens, and these birds are NOT chickens. The proper name for a hatchling hawk is an 'eyass,' pronounced EYE-ess."

So, now that we know how to name them, how do we tell them apart? Kay and I were down at the nest early Saturday and Sundays morning this weekend, and these pictures clearly show the difference in feather color and markings.




The tiercel/dad has a much lighter beak and chin area.









Right under his beak is a white bib that runs into his lovely cream chest, which has just a few scattered spots, almost like a delicate necklace.







The formel/mom, on the other hand, has a much darker bib under her beak - dark chocolate brown in color.





The spots on the formel's chest are more pronounced, almost in lines, and start much higher up.


When you see both birds together, the differences in their coloring are quite obvious. The problem right now is that they rarely turn their faces to the camera, so we don't often see their beak area.














In full flight, the pale coloring and delicate chest speckles of the tiercel are very clear.



Both hawks are now busy bringing materials to line the bowl of the nest. We discovered that some of the pine greenery is coming from a tree
behind the Franklin Institute, when we caught a glimpse of the tiercel caught in the act of pulling off a twig!






The tiercel also flew in with what looked like a pile of leaves from a gutter! Note his cool reflection in the window.



After all the nest activity, both hawks flew off to nearby trees. We saw the formel swoop for a mouse alongside the Vine Street exit ramp.She took her snack atop one of their favorite perching spots - the python-neck lamp posts that are so prevalent in the down-town area of Philadelphia.


The hawks are almost always in sight of their nest at the Franklin Institute. They sited it very effectively when they chose that top floor corner window ledge. In this picture, the hawks' window is the sixth window on the top floor counting to the right from the pillared portico of the Franklin Institute. You can see the tiercel perched on the lamp pole.





Surrounding our hawks are the skyscrapers of downtown Philadelphia. It is magical to watch how beautifully they have adapted to their urban terrain, choosing once more to build their nest here, and hopefully raise their young again, to our great delight!