John Blakeman on Red-tail Hawk Nest-Site Selection

Pale Male and Lola Switch on the Nest

Yesterday I published an excerpt from a news article in which the opinion was expressed that urban Red-tails preferred nests on buildings. John Blakeman took exception to this and here is what he has to say.

Donna,

Someone in one of your postings stated that Red-tails prefer to construct their nests on buildings and ledges, compared to trees, which move around too much.

Not so. Even in the West, where there are many cliffs, Red-tails generally prefer to place their nests in trees (if any are large enough there). This is particularly true with the Red-tails in the East and Midwest, where cliff-nesting Red-tails are virtually unknown in the wild.

Our birds instinctively prefer to put their nests in trees. Their genetic behaviors have this strong preference. But when tree nests don't seem to be preferable to a Red-tail, as when they are harassed by crows in the trees in Central Park, they will, as Pale Male and the others did, head up above the trees and nest on building ledges, free from the avian and human racket down below.

Yes, I designed a Red-tail "Nest Nook" device that could be bolted to a building wall or placed on a building ledge. But I'm not certain that this would actually attract a new Red-tail. Great-horned Owls, Ospreys, and Peregrines can be rather easily enticed to nest on created new nest platforms. But Red-tails seem to want to put their nests where they so arbitrarily decide. Nest site selection for this species is another of its great mysteries.

For example, the photo by www.palemale.com of the new (still meager) nest at a New York school window ledge is interesting. Just why there? Certainly there weren't any appropriate trees in the neighborhood, free from human and avian disturbances. But why this particular ledge, compared to the many others that also could have been chosen?

There does seem to be some unknown magic about some nest sites. I've watched in passing (at 65 mph) a single tree in the middle of a small woodlot here that has had a Red-tail nest on and off for over 25 years. Different birds, at different times. But repeatedly, new birds have chosen this tree over the several hundred other similar trees in the woodlot. Why? I don't know. It's hard trying to think like a Red-tail.

--John Blakeman

I don't know if we can generalize about Red-tailed Hawks, particularly those rather creative adaptable urban ones. Watching the sites urban Red-tails choose has given me the feeling that there is a set of criteria, perhaps some wired in and some learned from experience, known to the birds for nest site selection. We'll all most likely agree that there are few if any perfect nest sites and it seems to me that a bonded pair uses their judgement as to which are the most important criteria for them and choose a site accordingly. After a year some pairs build elsewhere, as Momma and Papa seem to be doing, whereas others hang in for years as Pale Male has done.

How much does successful hatching have to do with the change? Hard to tell, as Pale Male and Lola have now stuck into the fourth season of a three season failure run. Momma and Papa were successful last season and moved sites anyway.

What is the criteria? They know and we don't. Is the tree nest overhanging the road of the Riverside pair the best tree to hold a nest in the area? Quite possibly in their opinion and they may be quite right, but it can't possibly be the best place from which to fledge eyasses. Is safe flight of eyasses, one of the nest site criteria? If so it seems lower on the list for the Riverside Park pair than other criteria.

Another problem with urban tree nests at least in Central Park, and at up at Morningside Park as well, is the vulnerability of these nests to Crows. Crows may well have been a good part of the reason that Pale Male and his mate decided to make the revolutionary adaptation to nest on a NYC building. Attempting to protect a tree nest from Crows is what sent Pale Male and First Love to rehabbers in the first place. Pale Male's next serious nesting attempt was from 927 Fifth Avenue.

As forests become more and more truncated in the U.S. many species of breeding birds have become far more vulnerable to Crow predation. Our woods now have too many edges, as does Central Park with it's mostly widely spaced trees. More edges allow the sharp eyed Crows the visibility to spy out nest locations. A pair of Red-tails can stave off a murder of Crows from a nest with a wall to their backs. I've seen Pale Male and Lola do, and I've also seen Lola and Tristan do it. It is much harder for them to do with a 360 degree field of battle over a tree nest. Therefore in my opinion does an urban Red-tail pair prefer tree nests or building nests given their druthers?

It all depends, I think, on the blended hierarchy of the nest site criteria for any given pair of Red-tailed Hawks. The variables are legion, and John's right, it's hard to think like a Red-tail. Only they know their particular criteria. Sometimes that criteria puts them on buildings and sometimes in trees and that's where their criteria choices has led them to be.

Donegal Browne

P.S. We must also take into account that at least anecdotally form Peregrines to Red-tails where they hatched themselves, on a building, a bridge, a tree, or a cliff colors their own choices for a nesting site.

The Urban Renewal for Red-tail Nests Symposium is Now in Session

Photograph and update,

from Charlotte and Pale Male Jr. nest watcher, Brett Odom--

Both Junior and Charlotte have been making more frequent trips to the nest in the last few weeks. I even witnessed copulation on the top of 888 7th Ave. on Monday and yesterday I took the attached photo from my office. I think it is Charlotte leaving the nest with a branch, but all she did was circle a few times and then returned the branch to the nest (this was only a 135mm camera with no tripod so it's blurry, I plan on coming in over this weekend or next with my 400mm lens and tripod to take better photos). They both visit the actual nest, not just the building, several times a day so it does look like they will be returning to this nesting site this year. One of them is even sitting on the nest as I write this.

Brett Odom

There are now eight known Red-tail nests in Manhattan, some like the 888 nest and the Riverside Nest over the highway, are terrible spots for eyasses to fledge from.

Blog contributor and Hawk follower Robin of Illinois, was reading some old news items and sent in this reminder--

I was re-reading the articles from back when Pale Male's nest was taken down and spotted the paragraph below. I am wondering if anyone HAS provided platforms on their buildings to provide RTH nesting sites? (to hopefully include branching areas)

NY Times:Newly Homeless Above 5th Ave., Hawks Have Little to Build On

By THOMAS J. LUECK

Published: December 9, 2004

"Mr. Benepe said he would be happy to see Pale Male pick a tree in Central Park for his new nest, but added that the prospect was not good because red-tailed hawks prefer the stability of building facades to tree limbs, which sway in the wind. He said he would encourage building owners in Manhattan to provide platforms that might be claimed by Pale Male or other red-tailed hawks in search of a safe place."

John Blakeman designed platforms for nesting Red-tails both for buildings and also for trees which didn't have suitable branches. But as far as I know, no building owners have as yet taken the initiative to give Red-tails more options in the nesting site area.

Well, folks perhaps we should put on our thinking caps, get our creativity out of our pockets, and take on a little initiative ourselves. Can anyone think of buildings that would make grand sites for Red-tail nests if only they had a platform installed? Start brainstorming and looking around. That is step number one.

According to Brett Odom, 888 Seventh Avenue have been very cordial Red-tail hosts, by doing such things as postponing window washing and the like. Unfortunately 888 is a tough neighborhood for fledgling eyasses, being it is some blocks removed from a green space. Though now that I think of it, perhaps if something were created on which the eyasses could branch near the nest for a few days, perhaps their flight skills would be more up to the challenge of getting to Central Park unscathed.

It's time to brainstorm folks. Send in your thoughts on possible sites and what could be done to make temporary branching areas. One never knows where it could lead!

THE URBAN RENEWAL FOR RED-TAIL NEST SITES SYMPOSIUM IS NOW IN SESSION.

Donegal Browne

P.S. Be sure and go over to the links section, click on The City Birder, and check out the post for March 5th. Rob Jett saw some very interesting behavior which may bear on one of my theories.

Pale Male, Lola-Sticks on the Nest, Jr., and Charlotte

Pale Male atop the Carlyle Building, keeping an eye on the nest in a stiff wind.

Temperature: 43F. (It was supposed to be up to 54F. Tsk, tsk.)
Wind: Variable Gusts up to 40MPH

Sunny

2:44PM The nest looks empty.

2:46PM The word goes up from the Bench. Pale Male has arrived on the Carlyle.

2:51PM Lo and behold, the nest isn't empty after all. Lola comes out of the bowl. According to the hawk watchers on the Bench today, no one has reported Lola staying the night yet but she certainly has begun to look nesty. It could happen any day now.

(UPDATE: Not only could it, it did. Lincoln Karim reports that Lola stayed on the nest this evening, Thursday, instead of leaving to roost elsewhere. The hatch countdown begins!)

2:57PM She stands in the bowl looking around for several minutes and then adjusts a few twigs.

2:58PM Then she gets back in with just her head showing and scopes the area, I'm wondering if she has an egg in there..

2:59PM Then she gets up, head in bowl and does something for about a minute. Turning an egg?

Pale Male is still on the Carlyle light.

3:07PM He's looking down at something very fixedly.

A pair of Mourning Doves are sitting below Pale Male on the railing of Shipshape. Have they noticed Pale? Evidently they have as when the second picture is taken, it is of an empty railing. But then Pale Male's spot on the Carlyle has also suddenly become empty. He's flown south on Madison Avenue.

Lola preens.

Then she watches something very high that can't be seen by humans on the Bench.

More preening.

Back into the bowl but only half down.

3:39PM Then she gets up turns and disappears into the nest. No Redtails in sight.

Though the Robins are at work. How far away can Spring be when the Robins are pulling worms?

A thank you to Brett Odom for sending in this current photo of Pale Male Jr. and Charlotte's nest site at 888 7th Avenue. As you can see he has the optimum viewing spot. Which made me wonder just how Charlotte and Jr. were doing. Time to take a hike to the south end of the Central Park.

Fifth Avenue is on the one side of the park and the 888 nest is across the park and into the west side of town. I chose Central Park South to cross over, just in case Charlotte and Jr. might be doing some hanging around the old nest site on the Trump Parc. And to my surprise, upon looking up, there was a Red-tail circling. Possibly Junior.

Whoever it was, was circling into the trees and then out again. At least I thought so, but then I got the inkling that this was a larger bird. Charlotte?

Another pass.

Aha! It is Charlotte and Jr. and they are doing reverse circles with each other. One clockwise, the other counter clockwise.

They are beautiful and no doubt, well bonded.

Then off they go higher and further away, until they are out of sight.

Then from behind the Trump Parc, a V of geese appears.

Just one more sign of the Spring migration. Eggs, soon there will be eggs!

Donna Browne