Monday, December 20, 2004

BLAKEMAN ON THE NEST STRUCTURE

12/20/04-- I JUST RECEIVED THE FOLLOWING COMMUNICATION FROM JOHN BLAKEMAN, WHO HAS BEEN SHARING HIS EXPERTISE ABOUT REDTAILED HAWKS WITH ME AND THE NEW YORK CITY AUDUBON SINCE DAY 2 OF THIS CRISIS:

Marie,

I just had a very useful discussion with Dr. Tess Present, Acting Director of Science, Senior Scientist, Ecology & Conservation Science, of Audubon regarding what steps should be taken when the new nest-supporting device is installed. (I did not ask when this would happen, but apparently it will go up soon.)

First, the nest-supporting structure will not extend above the finished nest rim. That was a major concern of mine. The birds will now be able to land and take off unhindered by any structural contrivance. This is very, very good news.

The other question was what should be placed in the center of the new structure, if anything, to lure the birds back. All of the Audubon consultants apparently agreed that it would be best to place typical red-tail sticks in the center. I concurred and stated that they should be about a centimeter in diameter (thickness of ones little finger) and about 16-inches long or so.

I also strongly recommended that no attempt should be made to “reconstruct” the former nest, that no nest sculpting should be done in an attempt to restore the former nest bowl. The better maneuver would be to randomly place a flat pile of sticks in the center of the structure about 4 inches deep. This loose pile of sticks should not be compressed or secured in any way. That's what the birds will want to do on their own.

The only purpose of the new stick pile is to let the birds know that sticks are now supported there. That's all that's required. No one has the furniture delivery men decide how the living room will be arranged. Likewise, humans in a scaffold many stories over Fifth Avenue shouldn't try to decide how the Pale Male pair will want their nest furniture arranged. Like all couples with a New York flat, Pale Male and Lola will decide for themselves exactly how the sticks, the furniture, should be arranged.

And I pointed out that no one should be concerned if the pair is seen throwing out the new sticks. Frankly, the pair may have a biological urge to select, gather, and return its own twig collection. If I were to see the pair tossing out the new sticks in January, I’d be very positive about what's going on. That would mean that the pair has absolutely reclaimed the nest site and they are getting ready for the real activities which begin in February and March.

There was a question as to what kind of sticks should be used in this initial stick “seeding.” The old sticks from the removed nest are apparently available. But I strongly urged that these not be used, for these reasons. The sticks at the bottom of the old nest have been in the weather for years and are partially rotted and weak. I've watched my research redtails build nests, and they become extremely frustrated when they have to use partially decomposed sticks that break when they try to plunge them into the expanding nest structure. Don't use any of the old sticks. Some might be acceptable, but many would not be. Let the pair select their own new furniture. They aren't hurting for nest material. They've got all of Central Park's trees to select from. We know that nest building is a sexual and pair-bonding activity, so even though the pair will have to work harder getting the nest prepared this year, the pair will only be stronger for it. To borrow a domestic phrase, ”It's a good thing.”

I made one point to Audubon that all nest watchers should be aware of. I will not be surprised at all if the pair actually abandons all nest activity in January. The pair might be seen sitting on some distant building or corner of Central Park, apparently oblivious to the new nest. It might appear that the pair has abandoned the 927 site.

But that's because January is the depth of winter. Biological nesting prompts are not yet very strong. In most wild rural redtails, we seldom see nesting activity of any kind in January at New York city's latitude (the same as mine in northern Ohio). But as the day's begin to discernibly lengthen in February, the pair's sex hormones will flow profusely, resulting in all the proper nest-building and breeding behaviors seen before. This is a successful, experienced pair. They know exactly what to do, and when to do it. Building a nest in December or January isn't biologically important to redtails. In February and March it is.

So we must be patient. The nest-holding device that will go up is very good. No concerns about that. A few proper sticks will be placed up there by humans, to let our famous pair know with certainty that another breeding effort at this site is possible. But the pair will do things in its own time frame, not ours. I see nothing else that could or should be done now.

Nest watchers may want to keep track of the pair's nest refurbishment. Rural birds rebuild frequently, and the speed with which they build the major nest structure is remarkable. The bare crotch of a big tree can be vacant one day in February, and in just two or three days a bushel-basket sized nest frame appears.

Then, the birds will bring smaller leaves and twigs to line the nest. This is crucial, a process that young, inexperienced birds often fail at. The nest bottom must be tight and draft-free. First-year nests are often wide open, with winds easily blowing through the sticks and fatally cooling the eggs. But this pair will take great care in forming a tight nest bottom.

Lastly, watch for either of the pair (but the male most often) bringing a fresh green sprig of some evergreen to the nest. Virtually all redtails do this, even those in desert regions. We have no understanding of why. But don't be surprised to see Pale Male bringing a green twig of a Central Park evergreen to the nest during incubation and for a week or so after hatching. The only explanation is that the aromatic evergreen twigs tend to repel arthropod pests in the nest, but anyone who's ever been in a redtail's nest knows that this doesn't work. The evergreen sprigs are a mystery.

Altogether, I’m satisfied that all will go well, that the pair will resume successful breeding.
And even if it doesn't, I still wouldn't be overly concerned if they take a year off. Producing three eggs and feeding three eyasses to fledging requires an enormously draining effort. It is not uncommon for rural redtails to skip a breeding year every now and again, so don't lose heart of the pair decides to sit out this season. And a new male or female could show up in the following year. This happens frequently, too.

I commend everyone for their concerns and efforts in bringing all of this to the best possible resolution. You have focused the world's attention on your famous pair, which has brought recognition to red-tailed hawks across the continent. If redtails were as uncommon as peregrine falcons or bald eagles, many more would appreciate this regal and noble species. Sadly, out here in rural areas, where a redtail can be seen sitting on a utility pole every ten or twenty miles, the species is too often taken for granted, even dismissed. But New Yorkers, like they do to everything else so fine in the city, have regarded Pale Male and Lola as a special treasure. We commend all of you for the preservation of this nest site and wish everyone the best hawk-viewing possible. Your redtails now belong to all of us.

My best wishes to all, especially to Pale Male and Lola.

John A. Blakeman, falconer, raptor researcher
Northern Ohio