Saturday, February 11, 2006

West Drive Owls--last night and the night before

Left, the spiffy male; right, the "unmade bed" female
Photos by Bruce Yolton

Friday, February 10, 2006:

When I arrived at the West Drive "owl bench" at about 5:15 on this particularly raw and cold evening , the little gray screech-owl was not in his usual place at the opening of the roost-hole [or nest-hole, if my hunch is correct]. Only one owl-watcher was there, Miriam, who announced: "I think there's bad news."

While she had been watching the hole a few minutes before I arrived, she thought she had seen a squirrel coming out of the owl's residence. Squirrels had taken over the Riviera screech-owl roost hole a few weeks earlier. Now, Miriam said, it looked like the same thing had happened here.

"I think I can still see part of the squirrel in the roost-hole," Miriam said sadly. I trained my binoculars on the hole. Indeed, there was a gray, furry-looking thing showing at the very bottom of the opening.

But happily, screech-owls are also gray and furry-looking. At 5:25 the male owl took up his pre-fly-out position in the hole, looking like a perfect, well-groomed pussy-cat, gray and furry and cute as hell. A gray squirrel must have darted down the tree trunk, passing the roost hole just as Miriam had looked up.

Fly-out was at 5:50. By then Lee, Noreen, Donna, Jean, and Barbara were there. Lee and Donna went owl-chasing into the woods. The rest of us stayed at the bench, waiting for the female to fly out, or at least to poke her head up for a moment or two. Then Jean, who had seen the female on an earlier occasion, went and imprudently made a few comments about the female's appearance. "She looks like an unmade bed," she said, "like a little pile of laundry."

We laughed, for Jean was right: the female owl was definitely more scruffy-looking than the spiffy male. But obviously the lady took offence. We waited until our noses froze, but she never came out. Who can blame her. We left the park at about 6:15.

Here's Bob Levy's report on the more dramatic events of the night before, 2/9/06:

Six birders had just witnessed the fly-out of one of the two gray Eastern Screech-owls when I arrived at their home at 5:45 PM. I missed it by “"that much."

The other birders went in the same direction as the owl, trying to find where it had perched. I started to go with them but decided instead to watch for the second gray morph's exit. One of the other birders, someone I did not know, came back to watch with me. She wondered aloud when the owl might come out and I cautioned her that this "second" owl, probably the female, was unpredictable. Many times the majority of the birdwatchers gave up before she showed herself. Sometimes she popped up into the opening of the cavity only to drop back down out of sight one, two or even three times and then, after all that teasing, still did not come out.

However this evening, at 5:47PM, only two minutes after her mate had left, the female came up into the opening. She did not merely show her face as she usually does at first, but stood at full length. From her posture I reckoned she was ready to go. At 5:49 PM she did. She headed in the same direction as her mate. I alerted the other birders who had briefly re-located the first owl and now were looking for both.

But it was getting colder and all but Noreen, Lee and myself gave up and went home. We three went back to watch the cavity hoping to see one of the owls return, possibly with prey. At about 6:15PM Noreen and Lee, both hopping on one foot or the other in an effort to warm up, decided to give up their watch but not before getting my pledge to tell them what happened after they left.

Noreen and Lee, here is what transpired after you left: NADA. I remained until 6:40 PM but did not see either owl again. My fingertips had long succumbed to the cold but now that my toes were sending unpleasant messages I too ended my owling session.

PS. For those who want to know, I did not find the red morph Eastern Screech-Owl today. However it has been spotted in its "“old" studio apartment intermittently. I am beginning to suspect that this owl may move to another cavity when it is cold because its well-know den is very shallow and does not provide much protection from the weather. It may move around for other reasons but the low temperature might be one motivation

Friday, February 10, 2006

New York City has no monopoly on creeps

Read 'em and weep. From yesterday's Boston Globe:

A red-tailed hawk fed its chick in their nest on a ledge at 6 Beacon St. in mid-May 2005. Yesterday (bottom photo), only a few sticks were on the ledge as the hawks rebuilt. (Photos by David L. Ryan/ Globe Staff)

Vanishing of nests ruffles feathers

In heart of city, hawk pair's plight worries onlookers

The pair of red-tailed hawks that have made their home on an 11th-story ledge overlooking the Boston Common in the last year have become beloved residents of the neighborhood. In office buildings and homes for blocks around, their likenesses are on computer screensavers, in desktop picture frames, sent by e-mail from one bird-lover to the next.

But suspicion has suddenly torn through the little community of hawk-watchers. The birds' nests have repeatedly disappeared. Daily observers of the ledge at 6 Beacon St. say that the twig home first vanished last month. The hawks rebuilt, stick by stick. But the nest was soon gone again, and the birds once again rebuilt. Some say that, in all, three nests have mysteriously vaporized. The latest was Tuesday morning, and fingers are now being pointed.

Talk is fierce and accusatory: Possibly someone with an office near the ledge is disposing of them, some say, someone who would have to deal with dead rodents and the occasional screech of the birds outside the window. An attorney whose office looks over the site of the nest, and who says he is an object of such speculation, is shocked and hurt.

''Everybody's calling about the hawks," a visibly upset Guy Carbone said yesterday. ''I became daddy rabbit to those birds."

The fracas recalls a similar flap in New York, where a pair of red-tails, dubbed Pale Male and Lola, nested on a Fifth Avenue building overlooking Central Park. In that case, the building's resident board said the nest was a hazard and had it removed. Wildlife advocates and residents, including Mary Tyler Moore, picketed out front, until the birds were allowed to make their home there.

Thursday, February 09, 2006

PS about a book reading

I meant to include this in the latest posting. During recent weeks you've been reading here some of Bob Levy's reports about the various Central Park screech owls. Next month you can check out his Central Park Red-winged Blackbird [and red-faced birdwatcher] writings in his about-to-be-published book.

Wednesday, February 08, 2006

West Drive Screech Owl report and species information

Male, before fly-out Feb 5, 2006

Female before fly-out, Feb 5, 2006
Photos by Bruce Yolton

As the days grow longer, minute by minute, owl fly-out gets later. On Tuesday the little West Drive male took off at 5:41., heading westward as usual towards the little wooded area between the drive and the park-boundary wall. Almost immediately the somewhat lighter female was seen briefly as she poked her head out for a few seconds and then went down again.

Instead of joining the owl-followers I waited across from the nest tree, hoping to see the male return with prey . Ten minutes went by. Suddenly the female appeared at the hole entrance, peered into the darkness and whooosh! Out she flew into the same woods.

Uh oh, I thought, so much for my theory that there were already eggs in the hole. The night was cold. The eggs could not survive unattended for long. But even before I turned to go and tell the news to the other owl-followers-- Whooosh again. She was back.

It all happened too fast for me to see if by any chance she had caught a quick mouse before returning. But her swift return bolstered my conviction that a little owl family was in the making down in the West Drive nest hole.

A little after 6 the male returned to the hole. We saw him scoot in, but again it all happened too fast to see if he was carrying anything in his beak. A few minutes later he flew out again and though three owl watchers kept an eye on the hole for another half an hour nobody went in or out again. Still we were fairly certain that there was dinner on the table chez the West Drive Screech Owls.

Bob Levy, who has been sending in regular screech-owl reports , has sent in the following account of the species from the Cornell Birdhouse Network. It will give you an idea of what might lie ahead.

Eastern Screech Owl (Otus asio)

Western Screech Owl (Otus kennicottii)

Physical Description

The Eastern and Western Screech owls closely resemble each other, and in the past, the two species were classified as one. They are the most diverse in plumage color of all the North American owls, and variation in color is related to region. The Eastern Screech-Owl has two color morphs, rufous and gray; rufous individuals live mainly in the south and gray individuals in the north. The breast and belly are heavily streaked and spotted with black.

The Western Screech-Owl has only one color morph, gray, but individuals found along the northwest coast can be brownish. As with its eastern counterpart, the belly and breast of the western species are marked with blackish streaks and bars.

In both species, males and females look alike. They are approximately eight inches tall, with yellow eyes. They have ear tufts, which are conspicuous when raised. The two species can be differentiated by bill color and vocalization: Eastern Screech-Owls have a pale bill and make a descending trill or whinny vocalization. Western Screech-Owls have a dark bill and make a series of hollow whistles on one pitch, running into a tremolo, with the rhythm of a small ball bouncing to a standstill.

Distribution and Breeding Habitat

Eastern Screech-Owls are found east of the Rocky Mountains to the Atlantic. The species ranges from the Canadian boreal forests south to Mexico. They live in all forest types and prefer woodlands that are interspersed with the open clearings, meadows, and fields necessary for hunting. They also inhabit wetlands, orchards, suburban parks and gardens, and towns.

Western Screech-Owls range all along the western coast of the continent from Canada south to the Baja peninsula and into Mexico, and they are found as far east as the western border of Texas. They usually live at lower elevations and prefer open oak and riparian woodlands and seasonally wet areas. They also inhabit streamside groves, deserts, suburban parks, and gardens.

Eastern and Western Screech-Owls both compete with other species for nest sites, and their cavities are often usurped by fox squirrels, European Starlings, and Northern Flickers.


Screech owls are highly nocturnal, and therefore are rarely seen hunting and feeding. How soon after dark individuals begin to hunt depends on weather and food abundance; males tend to begin hunting earlier than females. Their diet is the most varied of any North American owl species, and is region-specific. They feed on insects, crayfish, earthworms, and all classes of vertebrates, including songbirds, fish, amphibians, and small mammals such as squirrels, shrews, rabbits, bats, and rodents. The owls swoop down from their perch to capture their prey; they rarely hover while hunting. Screech-Owls cache uneaten prey items in cavities.

Pair Formation and Territoriality

Screech owls are poorly studied, so information on their pair formation, territoriality, and nesting behavior is limited.

Before the breeding season, males defend an area containing several cavities. As part of patrolling their territories, males spend each night in a different cavity. The breeding season begins earlier in the southern regions of the species’ range, and its onset is affected by numerous factors, including weather, food availability, and the age of breeding adults. Once breeding begins, males concentrate less on territorial defense and more on courting females. Males perform elaborate courtship displays involving hopping, bowing, bill snapping, and presenting food to females. Male Screech-owls tend to be monogamous, but some are polygynous, forming pair bonds with more than one female. The degree of polygyny in a population depends on food availability and population densities. Individuals of the same age form pair bonds, and bonds are life long. Individuals will, however, find a new mate to replace one that has disappeared.

Nesting Behavior

Nest building: Female Screech-owls select a nest site from the cavities on the male’s territory. Females tend to choose cavities that have been well supplied with food by the male. They also prefer cavities in which they have successfully raised young in previous years.

Nests are typically found in natural cavities, abandoned woodpecker holes, and hollow stumps and limbs. The western species also nests in saguaro cactus cavities and abandoned magpie nests. Both species use nest boxes, and field studies show that boxes are selected as often as natural cavities for nest sites.

Screech-owls do not build nests but form a depression in whatever remnant materials (fur and feather debris from eaten prey) are in the cavity. In regions where Blind Snakes (genus Leptotyphlops) occur, these owls have been known to provision their nests with live Blind Snakes. It is believed that the snakes eat ant and fly larvae and pupae and, thereby decrease insect competition for stored food.

Egg laying: Screech-Owl females sit in the nest cavity a few days prior to egg laying. Eastern Screech-Owls lay three to four eggs in a clutch, and Western Screech-Owls lay two to five eggs. The first two to three eggs of the clutch are often laid two to three days apart; the remaining eggs are laid one per day. The eggs are white to creamy white and slightly glossy.

Throughout the nesting cycle, females stay in their nest cavity all day but leave briefly at dusk and near dawn. They are sensitive to disturbances during egg lying, and if disturbed they readily abandon their nests.

Males may roost within the cavity with the female throughout the nesting period.

Incubation: The incubation period is 26 to 30 days for Eastern Screech-Owls and 21 to 30 days for Western Screech-Owls. Incubation usually begins the day the first egg is laid. Only the female incubates, but during the day the male roosts in the cavity with the female or near the cavity. Males feed their mates during this period. Screech-owls are not easily frightened off the nest, and parents may attack intruders and perform distraction displays. Many birds habituate to human disturbances and react more passively, flying out of the nest when a human approaches.

Nestling care: Because incubation usually begins with the first egg, the eggs develop at different rates and therefore hatch asynchronously. Often two chicks hatch on the same day and the others on following days. Initially, the young are brooded by the female. After about 6 to 13 days, some young can thermoregulate, and the female stops brooding. At first, the male is responsible for providing food for the entire family. He delivers food to the female, who apportions it among the young. As the young get older, the female begins to hunt as well and gives food directly to the young.

After about 28 days, the nestlings leave the nest. Coaxed by their parents, who call to them and withhold food, they leave the nest just after sunset. Nestlings leave the nest in the order they hatched; older nestlings leave first and younger ones leave on following days. The young cannot fly when they leave the nest but can climb and hop from tree to tree. As they get older, the young begin to hunt and make longer flights. About seven to nine weeks out of the nest they begin to fly as well as their parents. The female roosts with dependent young, but the male does so only rarely. Fledglings are independent 8 to 10 weeks after leaving the nest.

If a nest is abandoned or preyed upon during the nesting cycle, the pair lays a replacement clutch. These clutches tend to contain fewer eggs. Both species raise one brood per breeding season.

Winter Movement and Dispersal

Screech owls do not migrate; they maintain home ranges throughout the winter. During severe weather, owls may move off of their home range to search for food. These owls are primarily solitary except during the breeding season. Pairs occasionally roost together during the winter in hollow trees, nest boxes, and trees with dense foliage.

At the end of the breeding season, parents become territorial and force young off their natal territory. Little is known about the dispersal of young, but dispersal distances appear to be similar for males and females and are affected by weather, food availability, and population density.

© 2001 Cornell Lab of Ornithology

Donna at the Hawkbench yesterday

Pale Male and Lola Plus Four More --- 7 Feb 2006

Rik reports that at 1:30PM Lola ate a pigeon on the south side of Dr. Fisher and then flew south.
1:42PM Arrival at the Hawk Bench. Pale Male and Lola circle above 927. Lola to nest, Pale Male to railing of Woody.
1:45 Lola up, flying with talons down, cruises over to Linda and then back past 927, past PM who watches her, soars to Madison and back. Pale Male up, both circle above 927, Lola disappears behind it. Lola reappears between Dr. Fisher and Linda. Lola circles above Linda then flies north over 5th Ave buildings.
1:47 Lola lands on the Oreo's antenna. Pale Male north, circles above Lola then lands beside her on Oreo antenna.
1:50 Lola flies toward the Ramble.
1:59 Pale Male up, flies to above 927 and herds two gulls higher and higher away from nest.
2:00 Pale Male heads for The Oreo Building than sharply turns and goes toward the Ramble, lost in trees.
2:06 Red-tail appears above Woody then to the NW.
2:25 8 Gulls above Model Boat Pond.
2:36 Lola lands on the NE corner of Woody, Pale Male circles above Octogon.
2:38 Pale Male lands on Carlyle 1 then switches to Carlyle 2 seconds later.
2:42 Lola up and to the north with speed.
2:43 Pale Male off the Carlyle, PM and L both dive N of Carlyle.
(At this point suddenly there are 6 Red-tailed Hawks in view from the Bench, even with Jean's aid we can't keep track of all the action. There are Pale Male and Lola by the Carlyle plus two Rts in the NW and two more RTs that appear and disappear intermittantly in the south.)
2:44 Lola zooms after the two RTs coming towards the Oreo.
2:45 Pale Male flies with speed to the nest, facing south, digs with his feet, twigs flip up. (Traction? A firm place to stand? Machismo?) Stands center, facing out, extremely alert.
2:46 Possible RT scream from the north, hard to hear, two retrievers are barking their heads off, while two dog owners are yelling at each other behind us.
2:48 Pale Male is up and off the nest, soars above Woody.
2:50 RT appears behind Octogon then behind Stovepipe. 2 RTs over Oreo.
2:51 1 RT coming in from the south, then a second. Pale Male(?) dives from above Fisher, chases them past The Crows, out of sight, several Red-tail screams come from behind the trees. Dog owner fight continues, more male voices added to the mix.
2:55 Pale Male above The Crows then ?, then back to The Crows. He dives towards the park and disappears in the trees.
2:58 Red-tail over Linda.
2:59 Pale Male to nest, digs, scans.
3:00 Pale Male works beak, focuses down.
3:01 Red-tail swoops from east to west over Kit's to past the Oreo.
3:02 Lola to ?
3:05 Pale Male alert, works beak again.
3:10 Lola above Octogon. PM off nest flies north with speed along the tree line of Fifth..??, then Oreo and Stovepipe.
3:13 One RT behind Oreo, one circling above, then above Kit's and Stovepipe.
3:16 Pale Male in front of Octogon, circles Shipshape, and Woody, then north , Shipshape and Carlyle, behind Octogon.
3:17 Pale Male in front of Linda, second RT (Lola?) in north, then Lola circles Rusty Top, then both circle Octogon, Lola past Woody. Pale Male flies up Fifth. Lola to scaffolding of Stovepipe.
3:22 Pale Male to Woody railing, Lola ?
3:2? Pale Male to Linda 2.
3:29 Exit.
Donna Browne

Tuesday, February 07, 2006

Screech conclusions

Last night at 5:40 the first of the West Drive screech-owls flew out of the roost hole. Flying low over the car road he headed west towards the park boundary wall. Almost immediately, even before the owl-followers could locate him, he caught something. He was spotted on a nearby branch minutes later, at about 5:44 or so, holding unidentified prey [almost certainly a mouse] in his talons.

Here is the exciting part: he did not proceed to break his long day's fast by devouring that caught critter. Instead, we saw him transfer the now-dead prey to his beak [the talons having done their job of killing] and head with it right back to the West Drive roost hole.

He flew out a minute or two after he entered, empty-beaked. Our solid conclusion: he was feeding a female in that hole. And why didn't she fly out and get her own dinner, as she has been seen to do on other occasions? Our equally solid conclusion: she was sitting on eggs down there.

Pale Male, Lola, and the Shipshape Building

The question has arisen as to why we don't use street numbers when we refer to the Fifth Avenue buildings that the hawks frequent. In fact, few people, even native New Yorkers, know the street numbers of the buildings. A name that provides a visual cue helps people spot the hawks in the moment far more quickly.

Look to the left, the building just north of Woody is the one that I call Shipshape. The square top is the water tower cover, the corners of which were infrequently used as a perch for Lola during copulation last season. The next two levels down are rounded, with railings that follow the curve. The top level is slightly inset above the second level.

Once there are eggs in the nest, on some days Pale Male will bring prey, already prepared, to the nest for Lola's dinner and she will eat it there. (If he doesn't prepare the prey beforehand Lola has been known to STARE at him until he does.) Other days, she will take it to a Shipshape railing to perch while eating it.

There are days as well, when Pale Male will prepare Lola's dinner while perching on one of the railings of Shipshape, then place it below the railing on the floor, take the short flight to the nest, and wait for Lola to take off for the hop over to Shipshape. Then he'll stand over the eggs, readjust a few twigs, dig with his foot, possibly turn the eggs, then fluff his feathers over them as he sits, waiting for her to return. In fact while Lola is eating on Shipshape, Pale Male has been known to use these moments for a quick nap.

Usually Lola will eat rapidly and whip right back to take over the nest again.

At least once last season, Pale Male hadn't even gotten to the sitting-on-the- eggs part of his job, involved with his pre-sitting down ritual, when Lola landed back on the nest, dinner in her talons. She'd decided to eat on site after all. Pale Male was up and gone in a flash.

It isn't that Pale Male appears to dislike sitting on the eggs, it's just that during the nesting period, Lola makes all the on site decisions.

And in the manner of waste conscious couples whatever the species, if Lola has dined at Shipshape and hasn't eaten all of her meal, Pale Male will return to the spot and finish it up for her.

What is that pigeon doing sitting on the scope, you ask? That is the friendly Two Toes. The wily Blue Bar Rock Dove who's figured out who's likely to have their lunch in their pack and has been known to find a way in and help herself.

Donna Browne

Was it "our" owl?

Website reader Susan Guinee sent this e-mail a few days ago.

This past Sunday morning, I saw a Great Horned Owl in Pelham Bay Park, Bronx (near Orchard Beach). I guess it is possible that the Central Park GHO has moved north a bit. I did not get a close look at his/her markings before he flew off but boy was it exciting to see the magnificent wing span.

Monday, February 06, 2006

At last

From the Pale Male website:

It Happened!

At 10:59AM Sunday morning Pale Male & Lola
mated on the scaffolding of the old Stovepipe

It happened again at 4:18PM when the couple
were seen on the chimney cover of The Oreo

Owling in the park with Bob

Two of last year's North Woods fledglings
photo by Cal Vornberger

Yesterday, though the weather had treacherously turned, I and a small number of birders gathered at the West Drive bench to see the Screech-owl flyout. [Farmers, of course, would not call the resumption of cold weather "treacherous." Warm weather in winter can ruin their crops.]
At 5:40 the first owl flew out and headed west. As we stood there in the penetrating cold waiting for the second owl to exit, along came Bob Levy, the author of the soon-to-be-published book about Central Park birding and birds --
Club George. He promised to stay a while longer and let us know if and when the second owl emerged. Gratefully we headed for a warmer spot...and the Rolling Stones at half time.

Bob kept his promise. Here is his report:

February 5, 2006 Central Park Owling

In truth, as opposed to “truthiness”, I remained behind to see if the second of the two gray morph Eastern Screech-Owls would fly out after you left with Noreen and Lee. I stayed past the 6:15 PM deadline I gave myself. By 6:35 PM I had still not seen the owl and I gave up.

Your readers will be interested to know that the red morph Eastern Screech-Owl was seen in its “old” tree cavity. At 5:38PM the small group of birders there heard the red morph make one tremolo call. It was especially enjoyable to hear this particular call because two of the birders, Ann Shanahan and Ken Hicks, had never heard the Eastern Screech-Owl before. Being with people who have a birding experience like that for the first time always increases my enjoyment of it as well. We all would have liked to hear the owl call again (a prior report says birders heard it call nine times) but a single call was all the owl had to say.

Yet the red morph did provide us with a bonus. When it flew out it stopped on a branch below but directly in front of its cavity. There is perched in the lamplight and preened, giving us a fantastic view. It stopped grooming when its head began to swivel to the north, then to the south and back again. We lost track of it after it dove down close to the ground heading southwest. There was no point following it. We lost track of it at once.

Sunday, February 05, 2006

Screech followers

Photo by Bruce Yolton

On Friday a group of owl prowlers attended the fly-out of the West Drive Screech-owl pair. The first owl made exit at 5:35 pm., heading almost due west towards the park wall at Central Park West. Almost immediately another owl was visible in the opening. She looked around briefly , and then flew out in the same direction as the first at 5:40.

Both owls were quickly located on branches of trees in the wooded area near the wall, first in separate trees, and finally sitting together on the same branch. Then observers, who included many of the Regular owl crowd and three delightful, enthusiastic, soft-spoken and polite children named Emily, Hannah and Carolyn , witnessed a little owl altercation. One owl seemed to lunge at the other, as if to say "Get lost, Buddy. This is my territory." After that we saw one owl head north, and the first one, the lunger, head south.

Why did I refer to the second owl to fly out of the West Drive hole as a she? Owl Regular Bob Levy sent me the following bit of information:

Here's one source for my statement that male Eastern Screech-Owls leave the tree cavity first. This direct quote is from the Cornell University Birdhouse Network website:

Screech owls are highly nocturnal, and therefore are rarely seen hunting and feeding. How soon after dark individuals begin to hunt depends on weather and food abundance; males tend to begin hunting earlier than females. Their diet is the most varied of any North American owl species, and is region-specific. They feed on insects, crayfish, earthworms, and all classes of vertebrates, including songbirds, fish, amphibians, and small mammals such as squirrels, shrews, rabbits, bats, and rodents. The owls swoop down from their perch to capture their prey; they rarely hover while hunting. Screech-Owls cache uneaten prey items in cavities.