READERS' THOUGHTS ABOUT NEST BUILDING AND LINING

READERS' THOUGHTS ABOUT NEST BUILDING AND LINING, the first by Jack Meyer [I once characterized him as a super-Regular] and the other from Lisa in Florida:

Marie- I just finished reading the latest John Blakeman letter. Perhaps our
Red-tails will take a hint from last summer's Wood Thrushes, and line the
nest with toilet paper! Jack

&

Hi Marie,

I would venture that the RTHs are ringing the nest with the pine needles for their essential oils. Essential oils are anti-viral, anti-bacterial, and anti-fungal. Nature's "pine sol" if you will. Thanks for all your work.

Best,

Lisa (in FL, former lifelong NYer)

2/20/05 --Why are there 5 Redtails at the Azalea Pond? Isn't that Pale Male's Territory?
JOHN BLAKEMAN RESPONDS:


Marie,

You forwarded a nice note from Sally and Peter Johnson where they noted five red-tails apparently associating together, or at least tolerating each other. None of these were Pale Male and Lola. The Johnson's noted that all of these birds were "juveniles," (exactly the same term for "immatures," birds in their first year).

This is unusual, of course. (But that’s true for so much of the rest of the Central Park red-tail saga.) Here’s my take on this.

Although the 927 nest is under daily construction, it’s still deep winter. Sex hormones are starting to flow, prompting the copulation and nest building being observed. But so far, there is no impending food shortage for any of the Central Park hawks. As I so often point out, food is everything for a hawk. If food is abundant and available, territorial imperatives recede. If resident hawks perceive that ample food is close at hand, they will be rather accommodating of intruders in the fall and winter. Prime red-tail habitats, areas with lots of prey, often have large fall and winter groups of hawks. In the winter, in prime areas, red-tails can be almost social, just as the Johnson's described in their email forwarded to me.

Presently, Pale Male and Lola have access to essentially unlimited prey animals. From this, they are expressing virtually no territorial defenses. Don't for a second think that our resident pair is inadvertently unaware of each of the other red-tails in Central Park. They see every wing flap of these youngsters and keep track of where they fly, perch, and hunt. Our experienced adults know and keep track of the entire red-tail scoreboard.

For now, the young hawks are hunting and eating in CP just like our celebrity pair. But let’s see how long this continues. All is well just now. Presently, there is a general raptorial rapprochement regarding hunting and perching venues. There is plenty to go around.

But things are likely to change significantly when Lola becomes gravid, when her first egg begins to form. Egg formation requires a large amount of calcium, proteins and lipids, which are all absorbed from the mother’s body tissues. Very quickly, the female’s outlook on life changes. I've watched this in the female red-tail in my captive breeding trials. When eggs begin to form, the female takes on a serious, even morbid attitude. Life instantly gets very, very serious.

Food becomes very important, and competition from interloping youngsters is likely to met with stern behavioral warnings to leave. Pale Male will perceive the new hunting and territorial regime, one that precludes un-needed competition from other nearby hawks.

The inordinate winter abundance of red-tails in Central Park is not likely to persist. For now, food is abundant. But when our resident adults begin to perceive that things could start to get tough, first to produce a pair or trio of eggs, then to help feed Lola during incubation, and finally, when eyasses have to be fed for 16 hours each day, our birds are likely to become downright intolerant.

Once again, the entire CP red-tail phenomenon revolves around the abundance of prey animals. If there is lots of food, there will be lots of hawks. When food begins to become harder to procure because of competition, the adults will either drive off the interlopers, or have a reduced brood size. If five or so immature red-tails remain and compete with Pale Male and Lola, only one or two eyasses may be produced this year. At worst, none would be. It could be an empty nest year.

It’s possible that the following could occur. What happens if the five immature winter hawks simply disregard the behavioral admonishments of the adults to scram, to leave the area? Would that be possible? Could be. Booting out one or two incursive intruders is a reasonable task for an experienced resident pair. But perhaps the five youngsters perceive that the pair of old fogey adults simply can't cover enough space to keep them out. As an adult chases after one youngster, another simply flies over to the abandoned space that the adult just left. If the immatures are impudently unresponsive (unlike your kids and mine, who perfectly responded to our adult admonitions), the entire process could devolve into something of an unproductive flying circus. Do we have now a gang of juvenile delinquents that might disrupt the normal conventions of red-tale domesticity? Let’s see what happens.

Again, I've never seen anything like this in the rural wild. This is all new. Nothing is decidedly settled. And should, perchance, this year’s brood size be reduced or altogether absent, don't fret. Let’s honestly prepare ourselves for what might become a biological reality, that the annual production of three-eyass broods is unsustainable and atypical.

As long as Pale Male and Lola had no hunting and prey competition, when they were the only game in town (or the Park), everything went their way. But that may no longer be the case. The rats and pigeon prey base may now have to be divided with, or shared among, some other Central Park hawks. At some point, a CP red-tail saturation point must be reached. Originally, I would have projected that a single pair exploiting the entire Park was saturation. I was wrong. There have been as many as three Central Park resident pairs in recent years, and now there are the added winter immature population. (After all, this is New York City. Residents of every species live closely packed together in high density.)

Let’s watch what develops. I'm betting that the intruding youngsters will be driven out and few or none will be seen in March and April. But a quite alternate scenario might develop, with unexpected, even untoward results for our pair.

And most of us just thought we were merely watching the uneventful lives of a single pair of red-tailed hawks. Nature is seldom so neat and tidy. Things in the wild are usually a continuing interplay of multiple forces and factors, just as are being seen with Pale Male and Lola. Isn't this as good as the plot of a great novel, the thematic development of a great symphony, or a walk through a great art exhibition?

Sincerely,

John A. Blakeman


FROM DONNA BROWNE, A HAWKWATCHER WITH SOME BACKGROUND IN FIELD BIOLOGY:

Dear Marie,
A number of things came to mind while reading your
Daring Hypothesis. [It's just below]

Within Homo sapiens, we accept without thought that
humans as individuals can be different from each other
in many and striking ways. Whereas in the past our
tendency with individuals of other species has often
been to see them as nearly identical within that
species particularly when it came to behavior.

We'd noticed and then proved to our satisfaction that
many species had "hardwired" instinctive behaviors.
Which we had a tendency to generalize to other similar
species or to mistake just where or when those
hard-wired urges stopped and learned behavior began.

For instance, a baby pigeon, nearly as soon as it's up
off it's haunches, has an urge to peck at things on
foot level, particularly small contrasting spots the
size of seeds. And as this behavior occurs whether the
squab has seen his parents eat or not, it appears that
members of Columba livia are hard-wired to know how to
eat. But in actuallity they are only hard-wired to
peck. The sequence of getting the seed into the
beak, and the swallowing-of-the-seed or the
drinking-of-water actions are learned. Young who never
see the adult example or who do not in duress figure
out the behavior on their own, die.
Having hand raised a number of squabs, I know that
there is a huge disparity amongst individuals as to
how long and intense a learning experience is needed
for success. I've a limited study group, but in my
opinion, what I'm watching is the difference in
individual intelligence for learning from observation
or figuring it out for themselves, barring the
traumatic negative eating misadventure. In shorthand,
some are just smarter than others.

We also took to be hardwired any animal behavior that
seemed universal in a species. We now know, that that
is not necessarily the case but rather sometimes a
learned behavior with excellent advantage for
survival.

Somewhere along the line a "smart" chimp learned to
choose and refine a twig for termite retrieval. Not
all chimps needed to be that inventive, others, we
think, learned from observation.

We also didn't know until lately that though the
chase-prey urge was wired in many species, that
exactly what to chase was not. Therefore the
"culture" of pigeon eating in Central Park for
Red-tails could have started with a "smart" Red-tail
watching another species do so as we suspect may have
happened with suet and "The Suet Eater" or a Red-tail
being smart enough or unafraid enough to eat a pigeon
inadvertantly nabbed by a sudden rush of the
chase-prey urge or killed by headlong flight into a
window.

The issue of raptors eating pigeons is a fascinating
one. Last winter during the extremely cold weather
when, as you may remember, the Bald Eagles followed
the ice down the river, I noticed every pigeon flush
from my terrace in a seemingly split second only to
look out the window and see an Immature Bald Eagle
staring at me from her momentary perch on my terrace
railing. She seemed as surprised as I was and took off
in pursuit of the fleeing pigeons.

For the last two days, I have sighted a Red-tail,
possibly a two year old, hunting the pigeons that
congregate on my 27th floor terrace at 43rd and 9th.
I have not seen this Red-tail succeed, she seems to be
using the Peregrine on the wing tactic, but if I do
I'll be fascinated to know if she's changed hunting
tactics. She too may well develop a taste for pigeon.

Actually this Red-tail's first sighting was made by
Quicksilver my parrot, who screamed and flung himself
precipitously to the floor, tipping me off by one of
the few "hard-wired" behaviors I've ever seen him
display, that a predator was outside. Take note, I'm
not saying he might not have have plenty of hard-wired
responses, it's just he lives with people in a New
York City apartment, one can imagine hard-wire
behavior stimuli just doesn't come up all that often.
Therefore one should not be fooled, just because a
bird may be hard-wired for certain behaviors, it does
not automatically discount behavior that we would
describe as thinking or intelligent. Silver is an
African Grey Parrot who because he has the tracheal
equipment, and was raised by English speaking humans,
is able to speak hundreds of words in context, and has
purportedly, though with a brain only the size of a
walnut, the capacity for having the IQ of a five year
old human child. Nevertheless he still screamed Awk!
and threw himself in the floor with the right stimuli.
Neither behavior is mutually exclusive.

Surely humans are not the only species for which there
are individuals that "think/act outside the box".

What about positioning a nest on a building instead of
using a tree? We might all agree that there is an
instinct to make a nest in Red-tails. Young birds
have the urge to build a nest but their initial skill
at nest building seems to be lacking. Then unless we
find that some kind of organic maturation process
within the Red-tail brain as it gets older is
responsible for better built nests, we could surmise
that better Red-tail nest building skills are learned.
And if they are learned by trial and
error/experimentation, that opens the way for a
"smart" bird faced with nesting failure to attempt out
of the ordinary strategies to make the nest "work" for
the next breeding season.

As for the younger hawks now attempting to nest on
buildings, beyond "reinventing the wheel", two
possibilities come to mind. Eeither they were raised
in a building sited nest (Pale Male and mate's
offspring?) or they have learned from Pale Male's
building sited nest's visual example.

Unless of course one wants to invest in Rupert
Sheldrake's theory that once any individual of a given
species figures out how to do something, it is far
easier for any other individual of that species to
figure it out and do it as well. One example being
the post WWII, bottle top removing, cream drinking,
Blue Tits in the UK.

There are several other aspects of Red-tail "culture"
in Central Park to be investigated as well. My
experience with comfort distance in country Red-tails
is similar to Mr. Blakemans, they won't allow me
within a country mile. Central Park hawks will eat in
a tree right above the heads of any number of humans.
Lola has been known while hunting to zoom down a path
two feet off the ground with one wing tip a scant foot
away from pedestrians. Did these birds never learn a
fear of humans and therefore arrived in Central Park
in the first place or have they revised it due to the
behavior of the current human population in their
environs?

Another question, what are all those Red-tails doing
so close to each other? Come to think of it, why is
that Red-tail so close to that Cooper's as well? As
has been suggested prey abundance in off breeding
season does seem to allow for less then the expected
inter and intra species aggression. Also suggested
has been that prey abundance allows for far smaller
territories during breeding as well. Is it possible
that what has always been taken as hard-wired
aggression may be based more on prey than was
suspected previously throughout the year? To take
that even further is it possible that much of the
Red-tails vaunted lack of social interaction even with
bonded mates, at least in our perception during much
of the year, is at least in part based on a lack of
prey as opposed to their being hard-wired loners?

Even as early as December when I found Pale Male and
Lola at evening, they had gone to roost in different
trees and no, there wasn't any snuggling going on, but
they were defintely within sight and sound of each
other. Giving these supposed loners the "flock"
advantage of predator warning by another who might be
in the intermittant brief awake period during the
other's intermittant brief asleep period. The
distance between the pair being advantageous as a
strategy against predators as well, as they are only
two. And though I've not seen the immature's roosting
habits this could conceivably hold true for the
Central Park immature hawks as well.

So many questions to be answered, so little time.
Sincerely, Donna Browne



My Daring Hypothesis: A Question For John Blakeman

There is a "plethora" of red-tailed hawks in Central Park and environs these days. I can't resist offering a somewhat audacious thought of my own:

Pale Male has been breeding successfully since 1995. Each of the 3 offspring of that first nest would have been ready to breed themselves by, let's say, 1998, and THOSE birds could have produced Pale Male grandkids by 2001. Then there are the three offspring of the 1996 nest, who could have each had young by 1999, and so on and so on. Meanwhile Pale Male and his mates have been producing eyasses year after year -- a total of 23 who lived to fledge.A mathematician would have to figure out how many possible Pale Male children, grandchildren, etc. there could be by now. Since it is a geometric progression, I'd bet that number is huge!

John Blakeman has previously written of the 23 offspring:"I'm certain that the majority died in their first summer." That was written on Dec.26., almost 2 months ago.[For this and other references to past Blakeman letters, scroll down on the LATEST NEWS page.] I wonder if his thinking has changed about this since then, as he has come to recognize that the NYC redtail explosion represents a possibly different reality than the situation he is most familiar with -- the rural and suburban redtail.

Obviously, I am not a biologist. Nevertheless I have a strong hunch -- partly stimulated by the timing of the local proliferation of redtails, partly by the fact that so many of the local hawks are making attempts to nest on building ledges rather than trees[unsuccessfully, so far, because of absence of spikes anywhere but at 927 Fifth]-- a strong hunch, as I say, that there is a connection between Pale Male and these proliferating NYC redtails. As I wrote to John Blakeman before, how extremely odd that before PM arrived in Central Park there were NO resident redtails in Manhattan. Now they're a dime a dozen.

I'd buy the no-more-boys-in-the suburbs-shooting-redtails hypothesis John proposed in a letter on Feb. 6, 2005, except that an alternate hypothesis makes more sense to me. I'm about to propose it, knowing well that I'm going way out on a limb, and that I really am unqualified to make scientific hypotheses at all! But perhaps it will stimulate an interesting answer, so here goes.

Is it possible that Pale Male is, in fact, some sort of evolutionary breakthrough? While Blakeman has written about the intelligence of hawks as compared to the Corvids or parrot families, [that is, that hawks are not the sharpest crayons in the avian box] perhaps Pale Male is actually a smarter redtail?

He has succeeded at building and maintaining for 11 years a pretty unique nest. He has managed for all that time not to eat a poisoned rat or pigeon, nor to collide with a truck on the highway, nor to fall prey to any of the various slings and arrows of outrageous fortune that others of his kind run into.

Maybe he has passed on this gene to a bunch of others who are managing to survive that perilous first year better than redtails did before, discovering new prey sources, perhaps. [Blakeman has speculated earlier, in a letter not posted, that pigeons might be an important factor here]. Anyhow, I've run this idea up the flagpole. Long may it wave.



Lincoln Karim
Pale Male with sprig of evergreen in bottom photo
[(See Blakeman comment below]
Marie,

The intelligent question was asked [by Karen Anne Kolling], “What do they line the nest with?” As the nest approaches full structural size, lining will be an important next step.

Right now, the nest is almost surely just a moderately intertwined pile of sticks. But this would not be able to retain the heat needed to incubate the eggs. Many first-time red-tail nests fail to get properly lined, and cool March winds blow right through the structures. Needless to say, the eggs laid in these insufficient nests fail to hatch. I've seen this quite often, frequently in marginal habitats, almost surely by newly-mated pairs that haven't learned yet how to properly prepare a successful nest. Pale Male’s first efforts may have been of this nature.

The nest lining has to be wind-tight. When watching either of the pair settle down on to the eggs to incubate, notice the deliberate manner in which this is done. What you can't see is that as the bird gently wiggles down onto the eggs, the parent is putting the naked skin of its abdomen right on to the eggs themselves. These bare patches can't be seen when the birds are flying, as they are under the outer body feathers. But before incubation the inner down feathers of the abdomen are lost, creating the “brood patch.” The brood patch seems to be larger on females than males.

So, while the birds are sitting on eggs, the adult’s body warmth is being transmitted directly into the egg. If the lining of the nest isn't tight, too much of that heat escapes and the embryo or unhatched chick (it’s not an eyass until it hatches) won't develop properly.

What, then, is the lining made of? It varies greatly, depending on what the birds have available. It’s usually some light, fluffy, fibrous plant material. The thin flakings of wild grape vine is used, as is the light, shedding bark of smaller dead tree limbs, providing little sheets of paper-like material that can be pressed together in the nest. Out here in rural Ohio, last season’s dead corn leaves are commonly used.

The birds will simply look for whatever is locally available. Most importantly, the material must be able to be tucked and compressed. Clumps of dead grass stems are often used. A fist-full of partially decayed (but dry) leaves works. It would be interesting to document the preferred lining materials of Pale Male and Lola. What does the vegetation of Central Park have to offer?

If they haven't yet, some time soon the pair is likely to start bringing sprigs of evergreens to the nest. No one has ever figured out exactly why this is done. A well-needled tip of a pine branch is brought to the nest and either tucked into it on the side, or sometimes arranged at the edge of the rim. The birds have a strong compulsion to do this, and out here in rural northern Ohio where evergreens of any sort are uncommon, we know that some birds have to fly several miles to find a valued pine or spruce tree. The best explanation is that the evergreen sprigs tend to repel feather lice and other invertebrate vermin – except that eyasses in their first weeks often are pestered by a number of bugs nonetheless. The green-sprigs-at-the-nest story is still an unexplained one.

This is an experienced, successful pair. They aren't doing anything new that they haven't done so very successfully before. Getting the apartment ready for the new brood of eyasses becomes important once again. Watch to see when lining material begins to appear at the nestsite. That’s rather equivalent to the buying of the bassinet and other accoutrements that human moms do when they know that live-giving things are about to happen.

As a falconer who gets to watch my red-tails hunt and kill, where I see close at hand their remarkable power, speed, and predatory determination, to watch their markedly converse behaviors of gentleness and care at the nest is always a striking contrast. At the nest, I still find red-tails almost totally out of character. I'll have some more comments on that when incubation starts. But to watch a red-tail at the nest is a special privilege, seeing it behave in considered ways seen nowhere else.

And New Yorkers can just go to the right spot in Central Park, ask to take a peek through a spotting scope, or just look up there with a pair of binoculars to see this remarkable spectacle. Although I've seen it here in the wild many times, I'm still a bit envious. You can see it both with ease and at length. Very special. Very special.

Sincerely,

John A. Blakeman


A defense of the Christo Gates that I rather agree with:

Hello Marie -- I've been an avid follower of your website since the co-op board tore down the original nest. Thank you, and Lincoln, and all the others who were instrumental in getting the nest rebuilt. May Pale Male and Lola enjoy many more years there.

Now, about The Gates: I think you are too hasty to condemn them. Years back, as bored teenagers in rural Maryland, my friends and I heard about "love-in's" taking place in a farmer's field. Well, we had to find out what this was all about so we went out to the field late on a Saturday night, dizzy with anticipation, and found a crowd of people had gathered to listen to a rock band that, in retrospect, was profoundly mediocre.

Who cared? It sounded great to us at the time! We were at a "happening." Did this "love-in" provide real love? Or great music? No. No more than Christo's Gates provide real art. But we loved the music and the crowd. It was a happening and we loved being part of it.

That's what I think The Gates provide. A "happening" that will be remembered as a focal point of people gathering together and feeling good about it. And don't forget those hot-dog vendors who tripled their daily wages!

Keep up the good work.

Carole




The Somerville Gates

CHRISTO AN INSPIRATION FOR GREAT ART

Great art inspires other artists. That much is clear. Finally I have to accept the greatness of Christo and Jeanne Claude, for they have inspired a genius in Somerville, Massachusetts.

You can get on the website showing the amazing Somerville Gates by clicking on the caption just below the photo. Once there, be sure you also click on About the Someville Gates, where you may enjoy the poignant comparison between the Christo Gates and the Somerville Gates, item by [hilarious] item.