Friday, March 21, 2008

Red-tailed Urban Nests-Scant Ones In Particular


Photo: D. Browne
Charlotte on the Trump Parc Nest-June 10, 2005
Note the depth and distribution of the nesting material.


Photo D. Browne


Night Falls: Charlotte on the Trump Park nest. June 14, 2005

Twigs had fallen from this side of the nest and we thought the "noodle" may have been added in an attempt to keep the twigs on. Now keep in mind this nest site had been used for at least three season and it didn't get larger it often seemed to get smaller until there was enough eyass feces to stick it down a bit better.



See the top of Big's head just past the item that looks very much like a kid's swimming pool noodle. (In order to use shorthand for the eyasses and minimize superflous words and typing , the largest eyass was named Big and the smallest Little.) Earlier they were Likes Rain and Doesn't Like Rain....too long and clumsy though originally funny

After reading John Brakeman's previous post that included some thoughts on the young hawks nesting on the air conditioner at PS 188, Brett Odom, who keenly watches Charlotte and Jr., emailed his thoughts on shallow nests and young hawks.


Donna,


I read your post from March 17 and noted where John Blakeman discusses the shallowness of the PS 188 nest and equates that with the youth and inexperience of the PS 188 pair and could be problematic in raising a successful brood.

While I certainly do not argue that the PS 188 pair is both young and inexperienced and their shallow nest which is built on an air conditioner cover could pose incubation problems, I would like to point out that Charlotte and Junior’s first nest at the 7th Ave. location was also incredibly shallow and the bowl of the nest possibly had some exposure to the foundation that the nest was built upon.

I say last year because this year they have added more nesting material and it is a slightly larger and deeper nest. However, because of its location behind a dirty window, it is very difficult to see exactly what shape the nest was in, even with binoculars and a spotting scope.


The most significant difference I see between the 7th Ave. nest and some of the other photographed nests around the City is that the 7th Ave. nest is not built on top of a foundation with obstructions (e.g. pigeon spikes) or material made of an open network (e.g., tree branches, metal mesh or grill work). Instead, it is built on a solid metal ledge. I would not be surprised if Junior and Charlotte?s nest last year was more donut shaped with very little "floor" since there was no fear of eggs dropping through the bottom of the nest or windy updrafts that would interfere with incubation.

Instead, the pair appeared to be more concerned with building high nest walls to keep any eggs from rolling away. Most of the other City nests, with a few exceptions, are either built in a tree, on some kind of open man made material or on top of pigeon spikes. Pale Male and Lola's nest had the unfortunate experience in the past few years of being built on top of metal mesh, open grill work and pigeon spikes (let's hope that with the removal of the pigeon spikes the nest will be successful this season).

All of these nests would require much more substantial and deeper nests to allow for proper incubation and allow for the required egg rolling by the adults without obstructions or eggs dropping through the nest bowl. I would think that at least with regard to Junior and Charlotte, last Year’s shallow nest was a product of 1) it being a first year nest, and 2) the location since it not only sits on top of a solid foundation which prevents windy updrafts that could interfere with proper incubation,it is also behind glass which protects it from wind and other natural elements. So, at least in this instance, I do not think that a shallow nest necessarily equated with inexperienced parents or posed a problem with successful incubation and hatching.

As most of New York City knows, thanks to covers on the NY Daily News and New York Post, Junior and Charlotte successfully raised a very capable red-tailed hawk fledgling last year.

Sincerely,

Brett B. Odom


Brett,


I sent your email on to John Blakeman and no doubt we'll have his thoughts on your thoughts soon. But in the meantime your step by step breakdown, made me think of a few things as well.
We've discussed in the past that perhaps a very firm foundation for a nest, such as the carriage on PM and L's nest, might fool the hawks into thinking they have enough material when perhaps they don't. Charlotte and Jr. had a firm foundation on the Trump Parc but it's hard to tell if it affected how much material was brought to the nest, because without a perimeter of pigeons spikes, almost all of their nesting material blew off every year.


Without the nesting material to raise the eggs up a certain amount I've always believed that the eggs tended to "drown" during intense periods of rain, then as the sides of the nest had blown away, the eggs being no longer alive lost weight and blew out as well. Or didn't drown, though I think water had something to do with it, (perhaps the subsequent chill with contact with the masonry, as their only successful hatch on the Trump occurred during the second clutch, warmer weather , and a drought, no water.)


It is very interesting to me that when they failed yet again and went looking for other digs, they chose a site in which there is very little wind. In fact they are doing something that I never thought that a Red-tail would do. They are virtually nesting in a box. I think that is a first. I know of no other RTs that have nested in a box but we don think that Jr. us urban born so more prone to creativity. It also shows that as C and J are building the sides of the nest high (as PM and L did yearly but not the bowl where their problem was perhaps coming from, because they were conceivably fooled by it's stability) they'd most likely wanted to build high sides but the material blew away, or fell off. Now they may have figured out that high sides keep eggs from rolling out so they aren't making that mistake again. Also note wind was a terrible problem for them..


They now have a virtually windless enclosure. Their initial criteria is definitely changed. No longer do they feel the need to be so far from people, nor so close to the park. In consequence they have far less wind to contend with and according to Brett far fewer neighbouring raptors at least for the moment. Jr. has done a number of observed firsts such as roosting on a building for the night as opposed to always roosting in a tree as the other urban RTs seem always to do at least so far. now he and Charlotte have gone and done it another first. And as always as other birds see it work they will follow suite.


But I still can not get over the fact that Junior and Charlotte are really and truly nesting in a box. They cannot survey a good bit of their territory without getting up, going to the door and sticking their heads out. I never thought I"d see the day.


P.S. One more thought on the AC nest, it has no perimeter of pigeon spikes, and therefore it may not be scant trips with twigs on the young parent's park it may be the twigs won't stay on. There were a pair of young hawks some years ago who repeatedly attempted to us air conditioning units and they could never get the nest to cling to the unit... no spikes, decorations, or protrusions to hold the nest together. Maybe that's how to help make nesting sites for RTs. Put perimeters of Pigeons spikes on large AC units. :-) Particularly if you see them attempting to use one.

P.P.S Rob from Bloomingdale Village and I were talking that in order not to have to call Isolde's new mate, Cathedral Mature Male just like Tristan her previous mate was called Cathedral Mature Male, which makes the whole thing generic and not specific, clarity after all being what science is about, forget just plain old communication, the new mate should have a name. We'd been calling him new mate, new guy, whatever but for brevity sake, we're looking for suggestions. You can either place your choice in the comments section her or got to the Bloomingdale Village link on the link bar and put your choice int he comment section there. Personally I like names that relate to physical characteristics or to behavioral attributes.

Tristan was a stealth hunter. He was extremely patient, standing around relaxed, one foot up waiting for game to come by. The new guy on the other hand is Mr. Energy. He whips around flushes pigeons in explosive clouds were ever he goes. I thought of Nitro, explosive but a bit too chemical. Currently I'm thinking about Flash or as he's Mr. Speedy there is Dash....
His penchant for squirrel--Squirrel Bane--too long. I did see him do something I'd not seen before. Most RT dispatch their prey with a squeeze of the talons or if young, hop up and down on it while holding it it both talons. The new male had caught a rat, it moved and instead of squeezing or doing the jump up and down bamming thing, he used one taloned foot and bopped it against the side of the tree trunk. Very unraptor like. Rather startling and unique actually. How about Bopper?

Donegal Browne

4 comments:

Karen Anne said...

Dash is sort of already in use. Dash and Concorde are the names of the Alcoa Anglesea peregrine falcon fledglings of 2007.

Anonymous said...

Hi! He sounds like Adonis to me!

Physical perfection.....beautiful, smart, clever!

Anyone like that one?

Donegal Browne said...

Not bad, I'll pass it on!

Donegal Browne said...

In regards to Dash, true. There was also the Kestrel Dash, the male in the pair Dash and Lily, the names of the Kestrels we watched on the Kestrel Cam until Dash was nabbed by a Cooper's Hawk laying in wait on the top of their nest box.