Saturday, September 30, 2006

How does Pale Male stay on that flagpole?

A reader, Karen Anne Kolling, wondered how Pale Male manages to keep a grip on that smooth, round ball atop the Belvedere Castle flagpole. Lincoln Karim, who took the picture, wondered as well on his website .Here's John Blakeman's explanation:


I, too, saw Lincoln's pondering of this question.

Actually, Pale Male is not physically gripping the sphere at all. He's merely perched on top of it. From the tossed feathers on the side of his head you can see that there is a slight breeze up there, but it's not enough to push him over. He's standing very erect, which also indicates that the winds are light. If they were stronger, he'd be leaning aerodynamically into the wind.

Therefore, the hawk is perched here in just the way my rural red-tails sit on the tops of wooden utility poles, which are flat or only slightly sloped.
Red-tails, and most other birds, too, can balance effortlessly on narrow perches. PM is balanced on this perch. He's not physically gripping it with any force. When I'm hunting with my red-tail Savanna, she, too, sits erect on my gloved fist, which is even smaller than this brass sphere. As we walk through a meadow searching for prey, she balances instantly as my fist moves back and forth. She does not tightly grip my fist at all. She merely sits and balances on it. It's actually quite remarkable, her ability to minutely shift leg and body muscles to accommodate our mutual motions (which are not unlike the motions encountered by the hawk on a small tree branch on a windy day).
Red-tails sitting in trees on small, waving branches, use the same techniques. It's primarily continually re-adjusting balance, not a firm, locking grip.

But the birds will use a locking grip when sleeping. They have a rasp-engaging set of circular muscles and tendons that wrap around the vertical tendons that extend between the leg muscles and the toes. When the bird goes to sleep on a windy night, she takes her perch and then tightens and locks the encircling muscles and tendons around the leg tendons. She falls asleep with the legs locked in a firm grip on the branch or other perch.
But I've seen red-tails just at dawn's first light sitting on a large, flat surface, where they couldn't have gripped anything. They slept the night through merely standing on the flat ledge. Any wind gust would have knocked them over during the night. But it appears that red-tails are rather able to discern the night's weather before they retire. If it's going to be a windy night, the bird will almost always select a branch perch around which they can lock their legs for the night. Just how they know if a night will be windy or not is not clear, but they seem to be very accurate in these predictions.

Lastly, however, we know that if weather changes, the birds can and do fly around at night to new or better perches. Having watched my trained red-tails for several decades, I believe that they can see at night just about as well as we can, so they can stubble upon a new branch if they have to.

That shot by Lincoln was pretty fine -- regal, if you will.

John Blakeman

Friday, September 29, 2006

About to change

Photo by Lloyd Spitalnik

The oddly mournful-looking creature above is a caterpillar of the Tiger Swallowtail butterfly. It was found in Central Park last week. The last caterpillar of this species I saw was a vivid green. Why is this one brown? According to the website of the Royal Alberta Museum in Canada:

"The caterpillar of this species changes dramatically as it goes through its various molts. In the first two instars (those periods between molts) it looks just like a bird dropping. It then changes to be predominantly green with two large eyespots near the front end. Just before pupating, the larva turns dark reddish brown."

Looks like our guy [or gal] is about to transform into a pupa. It will spend a happy winter in the Shakespeare Garden, we hope, although we don't know exactly where. In the spring it will eclose -- that is -- emerge-- as the beautiful yellow and black butterfly you are all familiar with.

Thursday, September 28, 2006

The Light in Shakespeare Garden

Not a moth stirring at the Moth Tree for at least a week.. So we set up the black light at the usual spot in the Shakespeare Garden. Lots of action there.

Present: Lee Stinchcomb, Jimmy Lewis, Allan Miller, Marie Winn [I took the pictures].

Corn Earworm - Heliothis zea - on the black light tube

The Gem - Orthonama obstipata --on sheet

Plume Moth [Pterophora sp.] on sheet
Cabbage Looper [Trichoplusia ni ] in closed resting position

Cabbage Looper, open position, perched on Jimmy's finger

Crickets, Bats [but no Cricket bats].

Cricket on rock outcrop at Cedar Hill

Restless Bush Cricket - male - Shakespeare Garden

A crevice at the base of a step in Shakespeare Garden

Cricket that came out of that crevice

Very small, one-legged cricket [female -- see ovipositor] that came out of the same crevice, on nearby pavement in Shakespeare Garden

Cricket Hunting

Photographing crickets is a challenging task. Though they've been singing throughout Central Park since the last days of July, and though their song sometimes seems to be coming from somewhere tantalizingly nearby, they are notoriously elusive creatures. If you get just a hair too close they cease singing and a few seconds later they'll resume, from a different place. Rarely do they pose for portraits.

I went for a cricket and katydid walk around the park on Monday evening [ 9/25/06] with Jay Holmes, Senior Educational Supervisor at the American Museum of Natural History.

We heard at least six different cricket songs. Near the Polish Statue at Turtle Pond we also heard the faint tick-tick-tick of an angle-winged Katydid.By dint of a lot of patience, and the museum man's sharp eyes and ears, we managed to spot and photograph four different species of crickets. The Katydid was somewhere high in a tree; not a chance of getting his picture.

I can only identify one of the four: the Restless Bush Cricket, which the Mothers-rhymes-with-authors have seen before and identified with the help of Nick Wagerik. It is responsible for the steady buzz you hear as you pass bushes in Strawberry Fields, in front of the Delacorte Theater, at the Shakespeare Garden, and many other flower beds in the park.

I've posted pictures of the three unknown crickets on Bug Guide, a great web resource for nature lovers wishing to get a name for mystery spiders and insects they've seen and photographed. Here's a link, in case you want to send in your own pictures. [They only want photos of live specimens!] You have to register, but it's well worth the trouble.

PS Rob Jett's bats
If there's one critter harder to photograph than a cricket it's a hunting bat . I wouldn't even try, though there are still many bats flying around the park's gardens and waterbodies at dusk. I was amazed to see that a Prospect Park naturalist and blogger, Robb Jett, succeeded in capturing [digitally] two Little Brown Bats as they circled around a meadow in the Brooklyn park. Below are his photos, by permission. And you might enjoy checking out his website:

Little Brown Bats, caught on the wing in Prospect Park

Sunday, September 24, 2006

Wrong again

I made a wrong call on another of Regina's insects I posted yesterday--see below. At least you'll see how hard this identifying business is. [Thanks Lloyd for the kind way you sent in your correction.]

Yellow-collared Scape [Cisseps fulvicollis]-- note orange collar and black head.
Photo by Regina Alvarez

Virginia Ctenucha [Ctenucha virginica] -- note orange head
Photo from Bug Guide

PS If you click on the photos you can make them bigger--and see more details.

It wasn't a fly

photo by Regina Alvarez

Two readers, Lloyd Spitalnik and Sheila Rosenberg, sent in an ID for one of the insects I posted without identification yesterday. I thought it was a wasp or a wasp-mimic fly, and put my money on the fly.: Neither wasp nor fly, it turned out to be a beetle: the Locust Borer [Megacyllene robiniae.]

"Many long-horned beetles are bright black and yellow, presumably to deter wasp-shy predators," writes Stephen Marshall in his new resource for amateur entomologists: Insects: Their natural history and diversity. It's pricey. Its index is maddening. Still it's a marvelous book and worth saving up for.