Saturday, March 03, 2007

Peeling bark for nest lining

Pale Male stripping bark on March 1, 2007
Photo from

When I saw the photo posted 3/2/07 of Pale Male stripping bark for the Fifth Ave nest, I sent John Blakeman a note asking if a different hormone kicks in when hawks move from bringing twigs to bringing nest lining materials, like bark. Here's his answer:


These are the only photos I know of red-tail bark stripping. Remarkable. There have been incidental and anecdotal written reports of this, but no one that I know of has ever photographed this.

As always, right in Central Park, of all places.

Yes, there is a sequence in nest building behaviors, but I don't think they are driven by different hormones. It's controlled or prompted by two factors, the first being hormone dosages the various endocrine glands are excreting. And that's almost completely a factor related to increasing day length.The curve of ascending day lengths is right now about as vertical as it can get. Back in January, day lengths were increasing, but minutely. In March, at our latitude (I'm pretty much straight west of NYC), we are gaining about 4 minutes of additional day light each day. For the red-tails, that's a breeding turn-on of the highest order.

The second factor in nest construction is the actual state of the existing nest. If it's somewhat dislodged or flimsy, the first order of business will be to bring in new sticks and twigs and thrust them together to make a firm structure.

Sticks will be brought to the nest throughout the entire nesting period, from January (or earlier) through May and June. That's just instinct, a ritualistic part of breeding. The real question is, are the sticks being tucked into the actual pile, to fill in the underlying stick pile? Or, are they just being ritualistically dropped on the surface or edge of the nest?

After the stick pile is firmly consolidated and feels secure, the birds next work on the lining, starting now, as in the remarkable photos at The birds start with more coarse lining materials, usually strips of bark, as shown in the photos. Progressively, the materials will get finer, with clumps of grass or leaves as the final, top layer. The female (primarily, with occasional help from the tiercel) will finally pluck off a few molting body feathers and add those to the lining material.

This sequence is all prompted by the same sexual hormones. The behaviors vary by the conditions at the nest, not be varying hormones. The coarser lining materials are early-March items (at our latitude). In a week or so, grass and weed bunches are likely to turn up.

One point everyone should recall here, lest anything apparently aberrant occur. It appears that the south end pair, last year on the Trump Parc building, is working on a nest elsewhere. Red-tail biologists really have no clue on why RT pairs simply abandon nests that they've use and start all over elsewhere. Some pairs seem to stay pretty stuck on a particular site, as with Pale Male at 927. But other pairs just fly away and build a new nest nearby every two or three years. I have a pair I've been watching for almost 20 years (new members of the pair, I'm sure) that flip from one woodlot to another every two or three years. I can't explain this.

But I wouldn't be alarmed if next year (it's not going to happen in 2007) Pale Male and his consort build a nest somewhere else in Central Park. If they do, it's not because they sat next to each other and had a serious talk about trying something new, in new digs. That's a degree of rationality these birds don't have.


John A. Blakeman

Friday, March 02, 2007


A harbinger of spring: the opening day of Jack Meyer's great Central Park walks has been set, for March 29.

These walks are enjoyable for all, beginners or advanced birders, young or old. Here is the schedule:

Walks will be Thursday through Sunday, from March 29 to May 27

Walks leave at 7:30 AM from 72 Street & Central Park West. (NE corner.)

The cost is $6. No reservations are needed.

If there are any questions, you can reach him at:
212-563-0038 (Not after 8 PM please)

See the total lunar eclipse tomorrow - March 3, 2007

progression of a lunar eclipse - from Wikipedia

Contributed by William Atkins

Without a total eclipse in almost two-and-one-half years, sky gazers will be able to observe a total lunar eclipse on Saturday, March 3, 2007 from the eastern Americas, the United Kingdom, Europe, Africa, Iceland, Greenaldn, Arctic, the Middle East in western Asia.

A total lunar eclipse is a complete obscuring of the full Moon by the Earth's shadow due to light from the Sun. It occurs when the Moon becomes darkened as it passes through the Earth’s red shadow. In the initial partial eclipse phase, the Moon will be dimmed by the Earth's outer shadow, or penumbra. Later, the Moon enters the Earth's inner shadow, or umbra; at which time it becomes a total lunar eclipse.

The eclipse begins at about 17:44 EST, or 5:44 p.m. EST) and ends at about 6:58 p.m. EST, with the maximum amount of eclipse being at about 6:21 p.m. EST. Thus, it is expected to last just over one hour, 14 minutes.

The event will be visible from parts of all seven continents on the Earth. In North America, the eclipse will already be happening the farther away from the east coast one is located; so the less of it you will see. The Moon will have risen before the total lunar eclipse begins when one observes it on and near the east coast. Further east, the eclipse will already be happening when the Moon rises over the eastern horizon at sunset on Saturday night. Across the Midwest and the Plains states, the total eclipse will have already happened by the time the Moon rises in the evening sky, so observers will only see a partial eclipse. Observers in the Rocky Mountain states will see even less of the eclipse, while West Coast viewers will miss it all together.

In Europe, Africa, and western Asia the eclipse will take place late in the night while the Moon is high in the sky.

Because of the lunar eclipse, the Moon will be colored a deep coppery-red. Its color is such because light from the Sun that impinges on the Earth is filtered and refracted (bent) by the Earth's atmosphere before reaching the Moon. Thus, the Moon will appear reddish; more specifically, bright red on its upper half while a darker shade of brown on its lower half.

According to NASA scientist Fred Espenak, of the Goddard Space Flight Center in Greenbelt, Maryland, there will be 7,718 partial and total eclipses in the five thousand years between 2000 B.C. and A.D. 3000. A second total lunar eclipse
will occur on August 27, 2007. It will be best observed, this time, in the western parts of the United States and in areas of
the Pacific Rim.

The NASA Eclipse Web page, from the Goddard Space Flight Center, is:

PS Nice quote from Plutarch about moon eclipses on Charlie Ridgway's blog

Thursday, March 01, 2007

What do hawks and dogs have in common, at least in February and March?

Lola on Beresford-- Feb. 26, '07
Photo by Bruce Yolton

Jack Meyer reports:

Both 927 red-tails were sitting in the big tree at the top of the hill from Ramble to Boathouse, at 8:00 this morning. Shortly after, I was told that they had copulated there & then flew off.

Later in the AM I saw one hawk (from my angle couldn't tell which) flying from Ramble toward 927 with a stick in its beak. Made me wonder if hawks & dogs evolved from a common ancestor, as both like to carry sticks around.

No new spring singers, but more of the same ones are making it really sound more like spring.

No more Phoebe count-down, as it's getting too close, and I'll almost certainly be off a few days one way or the other.


PS from Marie
Phoebe countdown = how many days until the arrival of one of the earliest migrants, the Phoebe. I say 13.

Monday, February 26, 2007

Ben sees Bald Eagle IN [not over] Central Park

Bald Eagle OVER Central Park on 12/27/06

Below, an amazing story of another BALD EAGLE, this one IN Central Park. Also a Red-tailed Hawk report of the same day. Be sure you go to Ben's website [click on link below] to see his recent eagle pictures, and to check out other interesting items about nature and astronomy.

DATE: Saturday, 24 February 2007 (7:50a-2:20p)
LOCATION: Central Park - reservoir to south end of park
OBSERVERS: Omar Morales, Ben Cacace

Even though the reservoir was almost completely frozen over we decided to take a trip around the running track. The only open water on the reservoir continues around the 'fountain' in the SW quadrant. In this opening were ~50 Canada Geese, 6 American Coots & several Ring-billed Gulls. It's unfortunate I didn't make an exact count of the gulls.

As we made our way along the east side of the reservoir heading north I noticed the gulls had just lifted off the reservoir. I always look for raptors in the sky when this happens since this is sometimes the reason for the scare. This time the reward was a juvenile Bald Eagle
carrying one of the Ring-billed Gulls. The eagle started climbing a bit but then started settling into descending loops and finally landed out in the middle of the reservoir on the ice.

There's a photo of the Bald Eagle on the reservoir at: or ...

It was almost immediately joined by 3 crows waiting on scraps.

We didn't spot the eagle arriving but saw it shortly after the gulls lifted. It already had the Ring-billed in its talons.

Also seen were 6 Red-tailed Hawks. Both sets of adults from the 5th Ave. nest and the Trump Parc nest. A Red-tailed was seen north of the reservoir. On my way to the south end there was a juvenile RT feasting on a pigeon just east of the Falconer's statue. A photo of the
juvenile Red-tailed Hawk is on the blog.

The male Northern Pintail continues on The Pond at the south end of
the park.

Sunday, February 25, 2007

Harbingers #3

Fox Sparrow
Photo by Lloyd Spitalnik

Below, the latest in Jack Meyer's Spring Singers Catalogue, received yesterday, 2/24/07. Note the postscript. It refers to the Estimated Time of Arrival [in days from the present] of one of the earliest spring migrants, the Eastern Phoebe. Today the magic number is 20.:


There was a newcomer to the concert this morning, a Fox Sparrow that very nicely perched near us & sang a few times. Despite the temperature, it was possible to believe spring was on the way this morning.


PS 21 days!