Friday, March 28, 2008

John Blakeman--A Plum Brook Station Report Plus Charles Preston Comments on NYC Cavity Nest

Photos: Donegal Browne
The 79th Street Riverside Park Nest, swaying gently directly above a well traveled road.

And here's the intrepid formel sitting tight and swaying right along with it.

If you can believe it, sharp eyed hawk expert John Blakeman has discovered yet another example of Red-tails, yes, building a nest directly above an auto thoroughfare.

And that's not the only reason that things are about to get very exciting at the NASA Plum Brook Station--


The NASA Plum Brook eagle appeared to be off her nest when I went in yesterday, but she was just hunkered down low in the nest. Hatching is scheduled for the end of the week or early next week, so things should get interesting soon.

I confirmed the occupation and incubation at a new Red-tail's nest I saw in February. It's a typical first-time nest, although this one is deep but narrow. The birds chose a very meager nest tree. It's hard to see how the sticks even stay lodged in the minor crotch. It's a tall but very thin cottonwood, which sways inordinately in the wind. But the formel is sitting very tight. She has to have an egg or two under her.

Then, several miles away in Plum Brook, I discovered a brand new nest in a smallish tree, on a branch hanging out directly over a road, perhaps in the manner of the Riverside nest. At first, when driving by, I thought this had to be crow's nest, but it looked a bit too thick. I backed up and put my binocs on the meager pile of sticks and there, too, was another sitting Red-tail. During the season, 20 or 30 cars a day will pass directly under the nest. It's on the road to the Space Power Facility, the world's largest space environment on the surface of the planet. There are 5400 acres within the Plum Brook fence line, and this young pair of Red-tails choose to build a nest 100 feet from the perimeter, above a well-used road, in a tree hardly big enough to support a bushel basket-sized Red-tail nest.

Red-tail behavior is not always very rational.

I should have some fun watching these three nests, however. I'll keep you posted.

--John Blakeman

I can't wait to hear what happens next!

When Charles R. Preston, PhD, author of Red-tailed Hawk in Wild Bird Guides, saw Brett Odom's photo and my musings as to whether there was anyone who knew of any other Red-tail box/cavity nests such as Charlotte and Junior's, he emailed me this comment--


The most similar situation I've seen for Red-tails is on a sandstone cliff space in Colorado, where the nest was placed in a large indention in the cliff face, partially covered by a column of rock. Very interesting!

Best wishes,


Next up: NYC Audubon attempted a raptor census this season, here is The Hawk Report for those who missed their mailing.

The results are listed based on the frequency of breeding by species in the city. Those who breed regularly and in greater numbers are listed first and in greater detail. A large number of birds were found through the census, including eight species confirmed to be breeding within city limits. In addition to the five diurnal species, three species of owl are found in the city year round and are covered separately from the diurnal species. Seven of those species are widespread, the eighth, Cooper’s Hawks, were confirmed as breeding only once. Species not confirmed as breeding within city limits, including migratory species, those found only in winter, and those species found in areas near the city and who may occasionally cross its borders, are not addressed in the same detail.

Cooper’s Hawks, Accipter cooperii
Cooper’s Hawks were the rarest of the species confirmed as breeding in the city with only one confirmed pair and two probable breeding pairs. They were reported in Brooklyn, the Bronx, Queens and Staten Island. The Bronx had no confirmed or probable breeders, Queens had two probable pairs and Staten Island had 1 confirmed pair.

Red-Tailed Hawks, Buteo jamaicensis
The census found 20 Red-tailed Hawk nests in addition to 12 pairs whose nest locations are unknown. Adult Red-tails have been recently sighted at four additional locations however further information was not available. The occurrences of reports of Confirmed or Probable breeding are as follows: three CO in Brooklyn, two CO and one PR in the Bronx, five CO and one PR in Manhattan, four CO and five PR in Queens, and seven CO and four PR in Staten Island. Among the known nesting locations the number of eggs laid and the number of young fledged is unknown. Some nests were monitored closely by various birders, others were not, either due to their remote locations, or the fact that a nest might only be known to a select few individuals. The offspring data that was collected was incomplete due to the same aforementioned factors. Therefore, the numbers obtained are incomplete. Citywide, 28 eyasses were recorded, split up among 12 nests. Two nests were known to have young but actual numbers were unknown. In these cases, the number of young in the nest was recorded as being one. Brooklyn had four young, Bronx had three, Manhattan had eight, Queens had seven and Staten Island had six young.

Two of the pairs whose nests were observed failed to rear young. One of these produced an egg which did not hatch. For the other, no data on eggs is available. All hatched young observed fledged successfully.

This census used a new method to gather information. In the NY Breeding Bird Census, volunteers walk or drive along predetermined routes. At set distances along the route they stop and record all the birds that they hear or see for a specified length of time. The specific quarry being censused, combined with the size of the area involved, made this a difficult approach to take; therefore, it was decided that information should be obtained by interviewing knowledgeable individuals.

Due to the nature of the methods used to gather information, getting precise numbers on any species was difficult. For some species such as Red-tailed Hawks and American Kestrels, the census data are likely lower than the actual numbers due to a lack of adequate coverage of certain areas (as with Red-tailed Hawks) and/or difficulty in finding the birds (as in kestrels). For other species, the numbers here might be higher than the actual ones due to mistaken identification, overlapping reports that are not recognized as such and inability to accurately assess the exact numbers found in an area. In all cases, steps were taken to be cautious and err on the low end. Nonetheless, the final numbers can be considered a fairly representative picture of the city's raptor population.

Cooper's Hawks were the rarest of the confirmed breeding species having only one breeding confirmation and two probable breeding pairs reported. It is notable however that the species is more common than that would suggest- in addition to the three pairs mentioned, Cooper's Hawks have been seen in five additional areas around the city, occurring in every borough except Manhattan. In all instances, the birds have been associated with parks or cemeteries.
Red-tails were the easiest birds on which to find information. They are large and conspicuous. Even better, they have a large number of devoted birders or hawk watchers who keep close track of them. The first pair of Red-tails to live in the city appears to have been Pale Male and Lola; they were first discovered living on 5th Avenue in 1991. Since then, the number of Red-tailed Hawks has grown. The numbers found in this census are likely lower than actual numbers.
While in the wild Red-tailed Hawks nest on trees or rocky ledges, New York City pairs seem to feel equally comfortable nesting on the sides or roofs of buildings. Of the nests whose locations are known, ten nests are built on trees and eleven are nesting on man-made structures. Seven of the latter were built on buildings, two were on bridges, one on a sculpture and one on a crane. A stronger need than nesting on trees or buildings seems to be nesting in or near parks. Of those 21 nests mentioned, only one is not located right next to or inside of a park.

Many of the Red-tailed Hawks in the city appear to maintain small territories compared with their rural counterparts. Moreover, at least one observer noted their increased tolerance, both of other Red-tails and members of other species, intruding on their territories. This could indicate that food availability is fairly high.The reproductive success of the observed nests is high. Two nests were known not to produce young; both of those had reportedly failed to do so last year as well. This may be a result of age or some other biological factor. In order to determine that, more research would need to be done. There does not appear to be a difference between the reproductive rates of those nesting on trees and those nesting on buildings or other structures.

There are still dangers associated with living in the city. One of the pairs that built their nest on a bridge inadvertently built it on a section of the bridge that was slated for demolition. In addition to the nest itself being in danger, nearby trees which could be used by the newly fledged chicks once they left the nest were removed. The wall was left up until the chicks left but what happened to them afterwards is unknown.

There you have it, or at least as much on population as they currently know. Okay, all you Raptor Watchers, let's try for scientific data in numerous categories next season, not just approximate population numbers. Not that population numbers aren't terrific, they are. It's just we could make more of a contribution to the anecdotal literature that might pique scientific interest. Who knows where that could lead? After all we have some of the best views, and the most human habituated raptors in the world!

Donegal Browne

1 comment:

Anonymous said...

The hawk sitting on the nest above the roadway is intrepid. I believe Intrepid would be an superb Christian name for her.

Allen W. in Sydney, Australia