Saturday, May 13, 2006

Shakespeare Garden Cocoon News

The Shakespeare Garden caterpillar-to-cocoon-to-butterfly story just reached its conclusion. It happened sometime yesterday before anybody arrived to check. That was around noon.

Black Swallowtail caterpillar day before transformation to cocoon- Oct 2, 2005

Cocoon on October 3, the day it was created
Photo by Lloyd Spitalnik

Cocoon November - one month later
Photo by M. Winn

Empty Cocoon - May 11, 2006
Photo by M. Winn

Blakeman response to questions about redtail nests

Before we get to Red-tailed Hawks, here's a photo of a migrant seen in big numbers throughout Central Park these days-- a Black-and-White Warbler.
Photo by Lloyd Spitalnik

A few days ago Christopher Lyons, a New York City birdwatcher who follows bird activity in Van Cortland Park, Prospect Park and other city parks, sent me some questions to forward to John Blakeman. JB sent back his answers, with Chris's questions in blue.

A pile of really good questions. Let me try to answer as many as I can.

I actually have a two-part question, both parts
relating to the Red-Tail pair currently nesting at
Fordham University in The Bronx. Last year, this pair
nested in an oak tree across from the Walsh Library,
and successfully fledged two chicks. This year, they
went about things very differently, and chose to build
a new nest on the horizontal cornice of a closed
triangular pediment, on top of Collins Hall. The
cornice, as you might guess, is liberally adorned with
pigeon spikes, which hold the sticks in place.

Incubation seemed to proceed on a similar schedule to
last year (maybe a little earlier), and Rose (the
female) began sitting regularly on the nest around
March 25th, with Hawkeye (the male) relieving her for
a few hours each day.

A live chick was sighted on May 4th, though feeding
behavior was observed several days before that. On
May 1st, however, a dead chick was found around the
corner of the building. It couldn't possibly have
fallen to that spot from the nest, nor does it seem
likely, given its state of development, that it would
have been able to get out of the nest at all.

...I'm obviously wondering what this
means to the speculations regarding the Fifth Ave.
hawk nests. Hawkeye and Rose have successfully
hatched out one chick, still apparently healthy (knock
wood), in a first-year nest built on pigeon wire.
There are significant differences between the Collins
Hall nest and the 927 Fifth Ave. nest, but the
similarities are equally striking.

I, too, saw the photo of the small dead eyass.

It is very clear that this little bird just barely made it out of the egg before it died. In fact, it may have fallen out of the egg after being punctured by a pigeon prong. It doesn't look entirely developed. The down appears too thin. I think this bird got dropped out its shell after at was broken, either while being rolled, or in normal incubating activities. This little eyass just doesn't look entirely developed. I don't think it ever was able to lift its head for single tidbit of food.

You also intelligently asked if red-tails are known to carry away dead hatchlings. You searched the ornithological literature and couldn't find any references on the subject. That's reasonable because a nest observer would have to be extremely fortunate to be able to document this singular event. It would be hard to clearly distinguish the carrying away of a little parcel like this. It would look like all the other trash the adults carry off.

I'm rather certain red-tails will carry away a dead eyass. A dead hatchling, as in the photo, just sits still and motionless on the bottom of the nest. Because it doesn't open its mouth or beg for food or try to scoot under the brooding mother, the adults would not be able to keep from thinking that the dead hawk is nothing more than another piece of dead food debris that should be carried off. I'm certain that's what happened to the photographed dead eyass.

I strongly suspect this very same pair [the adults of the dead hawkling] built a nest on an apartment building fire escape on nearby Creston Avenue in The Bronx, back in 2004. This site was directly across from St. James Park, adjacent to the Grand Concourse and Fordham Road. Two chicks were hatched out, but had to be removed by the DEP, along with the nest, due to unwholesome interest taken by some local youths. The adults did not try to renest in that area. The 2004 nest site is extremely close to the 2005 and 2006 nest sites at Fordham, and Rose has a band on her right leg. I've yet to directly confirm that the Creston Ave. female was banded in the course of that operation, but she was definitely handled, and the photos I've seen resemble Rose greatly. So this may be Hawkeye and Rose's second nest on a human structure, but it's almost certainly the first one they built on pigeon wire.

Anyway, curious to hear your thoughts.

Red-tails commonly abandon last season's nest and build a new one somewhere within a quarter or half mile. So the multiple nests you've observed of this pair is typical. In fact, the continued use of the 927 Fifth Ave nest in Central Park is the exception. Rural red-tails only infrequently continue to use the same nest year after year. They more commonly move around each year, just as you've seen in your area.

And of course, the question of pigeon prongs arises once again. It appears to me that the prongs in your referenced photoare rather short and thin. They might easily have been bent over in the center of the nest during construction. But without photos into the nest bottom, we'll never know. Just one of these little demons could have poked a premature hole in the egg just before pipping. Recall that I described previously how hawk egg shells are thinnest just before pipping. Chunks of metal, of any shape or length just have no positive benefit in red-tailed hawk nests. Just as with the 927 nest, the pigeon prongs artificially keep the nest together with a reduced depth. Not good.

Hope these thoughts are helpful.

--John A. Blakeman

Friday, May 12, 2006

Starling Villainy

Flicker excavating nest hole - 5/11/06
Photo by Lloyd Spitalnik
For the last few days Central Park birdwatchers have been watching a pair of flickers, [beautiful members of the Woodpecker family] excavating a nest hole in the Shakespeare Garden. Also noted, a pair of starlings on a nearby branch, quietly observing the hard-working flickers. We have seen the same drama many times in the past, but it is always heartbreaking. At the moment the excavation is completed, the native bird, ill-equipped by evolution to deal with this exotic newcomer [starlings were introduced to North America only a hundred or so years ago], faces a solid attack by the much-more agressive, sharp-billed starlings.

Every year birdwatchers are hopeful. But alas, this morning the starlings won the battle. The flickers, about to begin egg-laying, were fiercely attacked, and evicted, by the starling pair. It is now a starling nest in the Shakespeare Garden.

Note: The white spots in the photograph are bits of sawdust being flung out of the hole by the excavating bird. This is a rare photograph!

New policy will help owls

West Drive Owl- 2/5/06
Photo by Bruce Yolton

Owl and bird-watcher Barbara Kent sent in this article from the NY Times, noting that our male West Drive owl might still be alive if this policy had been implemented three months ago:

May 8, 2006

Additional Roadways in N.Y. Parks to Be Closed

Moving to further reduce traffic in city parks, Mayor Michael R. Bloomberg announced today that stretches of Central Park in Manhattan and Prospect Park in Brooklyn will close to cars under a six-month pilot program to begin June 5.

Under the plan, in Central Park, vehicles would no longer be able to use the East Drive of Central Park north of 72nd Street during weekday mornings or the West Drive in the afternoons. In Prospect Park traffic would lose morning access to the West Drive.

Officials said that the restrictions were intended to reduce potential conflicts between pedestrians and vehicles in the parks, and to increase weekday access for activities other than driving.

"For many years people coming to Prospect Park or Central Park for recreation during weekdays have had to share road space on the park drives with automobiles, and in all fairness it hasn't always been an easy relationship," Mr. Bloomberg said in Prospect Park as he announced the changes. "These new regulations will be especially welcome for the cyclists, joggers and inline skaters who use the park drive and it should also make entering and leaving the parks safer for pedestrians."

Officials estimated that approximately 865 vehicles would be affected by the Central Park closures and about 357 by those in Prospect Park. By contrast, Mr. Bloomberg said, on weekdays an average of 70,000 people use Central Park and 15,000 use Prospect Park. Officials said that they do not anticipate that the closures would unduly snarl traffic on streets surrounding the parks but said that they plan to study the affects of the changes in November with an eye toward making them permanent.

With the exception of the crosstown transverses in Central Park, both parks will remain closed to motor vehicles overnight and on weekends. In Central Park, only the West Drive will be open to cars between 7 a.m. and 10 a.m., while the East Drive north of 72nd Street will be open only from 3 p.m. to 7 p.m. From 72nd Street to 57th Street and 6th Avenue, the East Drive will continue to be open from 7 a.m. to 7 p.m. In Prospect Park, only the East Drive will be open from 7 a.m. to 9 a.m., while both the East and West Drives will be open between 5 p.m. and 7 p.m.

Thursday, May 11, 2006

Elm seeds - from Donna Browne's website

There's fascinating information lying at the sides of Central Park's roads -- for those who stop and notice. Donna does. Here's some recent entries from her new blog:
Donna's website:

Note the round beige spots on the ground. Those are the wings of the Elm fruit. These paper thin wings, after sailing the fruit through the air on the breeze, when dried, and brushed against the earth or park paths, wear away, and the small seed is left "unwrapped" on the ground. Currently they are everywhere. Piled alongside the paths, in drifts in gutters, heaped in any lee of the wind, waiting for Pigeons and Sparrows, Bobwhite and Grouse, Gray Squirrels and if we had any, Prairie Chickens and Opossum.
Photo by Donna Browne

More about elm seeds:

Dodging taxis in the crosswalk at Columbus Circle heading for the fountain, I suddenly see all these "things" in the air. Bits of pale paper from a malfuntioning incinerator? Snow in May? By the the time I've reached the center island there are thousands of them swirling in circles, ascending up and up and up, following the draft used so handily by the the Red-tailed Hawks to gain elevation. No they aren't paper and certainly they aren't snow. They are thousands of the flying fruit of the American Elm Tree. A common sight fifty years ago in the United States, but due to the devastation of Dutch Elm Disease, Central Park may be the only place where it can be seen today. Extraordinary lengths were undertaken to save the park's population of American Elms and the flying of their fruit is a very rare thing indeed. Not only for their beauty in flight for the human eye but for the birds and mammals who feast on them.

To see a larger than life detail photograph of the elm fruit, they are in reality about the size of a fingernail, click on the link below and go to nature observer Ben Cacace's site.

Wednesday, May 10, 2006

Things not so rosy elsewhere

Canada Warbler at the Point, 6/9/06
Photo by Lloyd Spitalnik

Where have all the warblers gone? was the title of a gloomy book a few years ago about the decline of migratory birds. The answer seems to be: To Central Park. We've been having as many birds of as many species as ever. But things are not so rosy elsewhere. Mary Birchard, a long time Central Park birdwatcher, sends this article from Time Magazine:

Sunday, May 7, 2006
Bye Bye Birdies
Populations of many migratory species have plummeted--and, in some cases, global warming seems to be at fault

Even after an unusually mild winter, the return of spring to North America feels like a blessing. Parents are dragging their toddlers to the park. Students are dusting off their Frisbees. And bird watchers, armed with binoculars and guidebooks, are heading out to search for their favorite species.

But the birders may be in for a disappointment. Radar studies of annual migrations suggest that the number of birds winging along America's flyways may be down by nearly 50% over the past 30 years, and data from the U.S. Geological Survey's annual Breeding Bird Survey and the Audubon Society's Christmas Bird Count reflect a similar decline. Various reasons for the falloff have been proposed, but climate change caused by global warming is high on the list for many experts.

The evidence has so far been largely circumstantial, however, which is why a study in the current issue of Nature is so intriguing. Building on some 40 years of bird counts, Dutch scientists report that populations of a migratory species called the pied flycatcher have plummeted an astonishing 90% over the past two decades in some areas of the Netherlands. And in that case, there doesn't seem to be any doubt about why: flycatchers are on the wane because climate change has made them late for dinner.

Those agile, acrobatic birds spend the winter in West Africa and return to their Netherlands nesting grounds in the spring to lay eggs. When their hatchlings emerge, the parents feed them mostly with caterpillars. The timing of the flycatchers' migration has evolved over many thousands of years to coincide with an approximately three-week period after Dutch plants have flowered and caterpillars are most abundant.

Thanks to warmer average temperatures, however, plants in some parts of the Netherlands are flowering an average of 16 days earlier in the spring. The birds in West Africa don't know that; they still leave more or less at the usual time. And while the early spring they encounter in the north has induced them to move up egg laying a bit, they're still producing offspring nearly a week behind prime caterpillar season. Inadequate nourishment means dying birds and falling populations. "We think this is the first time anyone has really shown that an insufficient response to climate change can cause population declines," says study co-author Christiaan Both of the Netherlands Institute of Ecology.

But it's probably not the last. Global warming might explain some migratory-bird declines in North America as well, although Greg Butcher, director of bird conservation at the Audubon Society, warns that it is dangerous to make assumptions. "It's great," he says, "when you have a bird like the pied flycatcher, which has been studied for years, and you have enough detail to pinpoint what the problem is." The populations of some seabirds, such as kittiwake, are plunging not because the birds are having trouble timing their food supply but because the fish they feed on have shifted locations.

Other birds seem to be in trouble because of habitat loss. The decline of the rusty blackbird, for example—one of the most rapidly dwindling species in North America, says Butcher—may also be due to global warming, but the immediate cause seems to be a drying up of the Canadian wetlands where it breeds. The same may apply to the Canada warbler. The cerulean warbler, also in decline, is losing habitat not because of global warming but because of another human activity: the destruction of Appalachian mountaintop forests by coal-mining operations.

And some birds are actually doing fine, adjusting to change and even increasing their numbers--at least in the bird counts. Some hummingbirds, for example, that used to winter in Mexico don't bother to make the trip anymore because the U.S. is now warm enough all year long. A number of migratory species that nest in northeastern forests have rebounded because that part of the country is reforesting as agriculture declines. Bluebirds are thriving, says Butcher, because bluebird lovers have been setting up nesting boxes for them for the past half-century.

But even those success stories can be troubling. Natural ecosystems evolved at a glacial pace, over millenniums. And while human-induced change may help some species thrive, it can also throw off the balance that keeps an ecosystem healthy--as some hungry Dutch hatchlings have discovered.

With reporting by Reported by David Bjerklie/ New York

Tuesday, May 09, 2006

Little bird causes big stir in park

Prothonotary Warbler at the Point - May 9, 2006
Photo by Lloyd Spitalnik
This morning at about 8 a.m. I was at the Point with a group from the Natural History museum when I ran into Ken Gale. He's a birder I've known for many years who shows up at about this time every year -- a migratory birdwatcher. This time he looked a little distressed. He was thinking about a bird he had seen a few minutes earlier. Could it have been...? No, not possible.. But what else could it have been...? Back and forth. He wrote a letter about his morning's experience on e-birds a few hours later. This is what he wrote:

Hi, folks,
The short and the long of it:

The short:
A first year male or particularly bright female PROTHONOTARY
WARBLER was being active for quite a while mid-morning between Bow Bridge, The Point and Willow Rock, both sides of the lake, usually over the water, frequently more visible from the opposite shore than the near shore.

The long:
Attitude is a big part of birding. It had been a slow day for
birding when I first saw it. I was alone 1/3 the way on The Point, checking the activity in the willow near Willow Rock. I got a clear look at it, noted it had the "angular" head shape of a Prothonotary then shrugged it off as a female Yellowthroat, my first of the year. It wasn't until I was nearly at the end of The Point that I realized "Female Yellowthroats don't have yellow on the TOPS of their heads." I checked a field guide and realized my first thought was correct: I had a female Prothonotary Warbler, but I was so cynical I decided it couldn't be, like I couldn't be the first person to see a bird like that. My negative attitude kept me from following the bird when it left the willow or telling anyone about it right away. Luckily, some of the people I told about later saw it and eventually dozens of birders saw it. People were going up to me saying, "You're vindicated, Ken."

But of course I'm cynical, I do a show on WBAI ;-) (if you're up early tomorrow morning (Wednesday), I'll be on the air interviewing the writer Arnold Drake).

Happy bird-day,

Ken Gale, NYC (my April 4 radio show was
on birds and birding and is archived on line)

Trump Parc update and Blakeman answer to reader's question

Pale Male Junior soaring over Central Park South - 5/6/06
Photo by Lincoln Karim

This dispatch just in from our informant whose window looks directly down into Junior and Charlotte's nest

Just to bring you up to date, the female is still on the nest, and she is sitting on one egg.
Nothing new.

Next, a related question from website reader Paul Pollets :

Hi Marie,

I was wondering if there are ever cases when RT hawks will lay another set of eggs in the same season, if the first set doesn’t hatch?

As usual I forwarded it to John Blakeman in Ohio. Here is his response:

Good question. I'm sure red-tails are able to do this. In captive breeding of almost all raptors, including the Buteos (which includes the red-tails), initial clutches of eggs can be removed just before hatching and if sufficient food is available, a new clutch is often laid. So yes, a second clutch can be laid.
But sadly, it probably won't be. I've never seen this in a wild nest, except for what happened last year with the Trump Parc pair, where apparently the nest fell apart and an egg or two rolled out and died. That was equivalent to deliberate egg removal, prompting the laying of a new clutch.
It appears that unhatched eggs are still present in both Central Park nests, so the females dutifully continue to incubate. As I noted before, the parents don't count days till hatching. Only humans do that. Hawks can't count days. They only discern increasing day lengths, which prompts them to sit on eggs. They merely wait until the eggs hatch, and if they don't, they continue to sit until the days aren't getting much longer. That changes their hormones and they finally give up on incubating. By then, usually sometime in May at the New York or Ohio latitude, they just give up on incubating and resume the normal life activities of hunting and killing food.
So the chances for a second clutch being laid at either Central Park nest is now highly remote. Unless the existing eggs would be removed, the parents will have no physiologic or behavioral prompts to begin everything all over again. It's getting very late in the season. Copulation is either rare or completely abandoned by now.
The only positive factor would be the great availability of food for the red-tails in Central Park. When food is limited, egg laying is reduced. Where prey is hard to find, red-tails often hatch or raise only a single eyass. With more food, two are typical. Three eggs or eyasses are produced only in territories that have abundant prey animals (along with experienced adults able to consistently kill the available prey -- as we've seen in Central Park).
Again, I've never seen a wild red-tail pair recycle and lay or rear a second clutch of eggs this late in the season. It's now too late in the season for this to happen with any certainty.
--John A. Blakeman

Reading for Mothers Day

In light of our recent discussion of redtail emotions, here's an article from this morning's NY Times.:

May 9, 2006

One Thing They Aren't: Maternal

Oh, mothers! Dear noble, selfless, tender and ferocious defenders of progeny all across nature's phylogeny: How well you deserve our admiration as Mother's Day draws near, and how photogenically you grace the greeting cards that we thrifty offspring will send in lieu of a proper gift.

Here is a mother guinea hen, trailed by a dozen cotton-ball chicks. Here a mother panda and a baby panda share a stalk of bamboo, while over there, a great black eagle dam carries food to her waiting young. We love you, Mom, you're our port in the storm. You alone help clip Mother Nature's bloodstained claws.

But wait. That guinea hen is walking awfully fast. In fact, her brood cannot quite keep up with her, and by the end of the day, whoops, only two chicks still straggle behind. And the mama panda, did she not give birth to twins? So why did just one little panda emerge from her den? As for the African black eagle, her nest is less a Hallmark poem than an Edgar Allan Poe. The mother has gathered prey in abundance, and has hyrax carcasses to spare. Yet she feeds only one of her two eaglets, then stands by looking bored as the fattened bird repeatedly pecks its starving sibling to death.

What is wrong with these coldhearted mothers, to give life then carelessly toss it away? Are they freaks or diseased or unnatural? Cackling mad like Piper Laurie in "Carrie"?

In a word — ha. As much as we may like to believe that mother animals are designed to nurture and protect their young, to fight to the death, if need be, to keep their offspring alive, in fact, nature abounds with mothers that defy the standard maternal script in a raft of macabre ways. There are mothers that zestily eat their young and mothers that drink their young's blood. Mothers that pit one young against the other in a fight to the death and mothers that raise one set of their babies on the flesh of their siblings.

Among several mammals, including lions, mice and monkeys, females will either spontaneously abort their fetuses or abandon their newborns when times prove rocky or a new male swaggers into town.

Other mothers, like pandas, practice a postnatal form of family planning, giving birth to what may be thought of as an heir and a spare, and then, when the heir fares well, walking away from the spare with nary a fare-thee-well.

"Pandas frequently give birth to twins, but they virtually never raise two babies," said Scott Forbes, a professor of biology at the University of Winnipeg. "This is the dark side of pandas, that they have two and throw one away."

It is also something that zoos with ever-popular panda displays rarely discuss.

"They consider it bad P.R. for the pandas," Dr. Forbes said.

Researchers long viewed infanticide and similar acts of maternal skulduggery as pathological, a result of the mother's being under extreme stress. A farmer's child pokes around in a rabbit's nest, for example, and the mother rabbit responds by methodically consuming every one of her eight baby bunnies. By standard reckoning, it made little genetic sense for a mother to destroy her young, and maternal nurturing was assumed to be a hard-wired affair.

More recently, scientists have accrued abundant evidence that "bad" mothering is common in nature and that it is often a centerpiece of the reproductive game plan.

In the blockbuster movie "The March of the Penguins," the emperor penguins were portrayed as fairy parents, loving every egg they laid and mourning every egg that cracked before its time. Among the less storied royal penguins, a mother lays two eggs each breeding season, the second 60 percent larger than the first. Just before the second egg is laid, the mother unsentimentally rolls the first egg right out of the nest.

In Magellanic penguins, the mother also lays two eggs and allows both to hatch; only then does she begin to discriminate. Of the fish she brings to the nest, she gives 90 percent to the larger chick, even as the smaller one howls for food. In the pitiless cold of Antarctica, the underfed bird invariably dies.

Like penguins, many species that habitually jettison a portion of their progeny live in harsh or uncertain environments, where young are easily lost and it pays to have a backup. At the same time, the harshness and uncertainty make it virtually impossible for a mother to raise multiples, so if the primary survives, the backup must go. Sometimes the mother does the dirty work herself. More often, she leaves it to her preferred young to dispatch of its understudy.

When Douglas W. Mock of the University of Oklahoma began studying egrets in Texas three decades ago, he knew that the bigger babies in a clutch would peck the smaller ones to death. Still, Dr. Mock was caught off guard by what he saw — or failed to see. He had assumed that the murderous attacks would surely take place while Mom and Dad egret were out fishing.

"I figured that, if the parents were around, they'd try to block these things," he said. "I have three older brothers, and I never would have made it if my parents hadn't interceded."

Instead, Dr. Mock witnessed utter parental indifference. The mother or father would stand by the side of the nest, doing nothing as one chick battered its sibling bloody. "The parent would yawn or groom itself and look completely blasé," said Dr. Mock, author of "More Than Kin and Less Than Kind: The Evolution of Family Conflict." "In the 3,000 attacks that I witnessed, I never saw a parent try to stop one. It's as though they expect it to happen."

Since then, siblicide under parental supervision has been observed in many bird species, including pelicans, cranes and blue-footed boobies.

One researcher watched a nest of African black eagles for three days as the larger eaglet alternated between tirelessly stabbing at its sibling and taking food from its solicitous mother's mouth. There was prey to spare, but the mother did not bother feeding the second, abused baby. When the eaglet's poor, tattered body was finally tossed to the ground, the researcher calculated that it had been pecked 1,569 times.

Pigs, too, have their own version of litter culling by sibling rivalry. Piglets are born with little eyeteeth that stick out sideways from their lower jaw, Dr. Mock said, and they use these teeth to slice at the faces of one another as they jockey for the best teats. The runt of the litter is so often sliced and bullied that it cannot get enough milk. It must spend every spare moment fighting to nurse and may get crushed by its mother.

In other cases, mothers turn infanticidal because they are born optimists, ever tuned to the sunny expectation that good times lie ahead. Each year they breed for a banquet, producing a maximum of begging bairns as the season starts; and when there is plenty of food, they will provision every young.

If the feast does not materialize, however, they cut their losses. Kangaroos have an elaborate method for child rearing through fat and lean years. In a good season, a mother may care for three offspring simultaneously, each at a different stage of development: the eldest, already hopping around on its own but still nursing; the second, a joey, which lives in her pouch and breast-feeds; and the youngest, an embryo stashed internally in a state of suspended animation.

During a severe drought, the mother will first refuse her breast to the autonomous juvenile, leaving it to forage as best it can. If the drought continues, her milk dries up and the joey dies and falls from her pouch. At that point, the embryo kept in cold storage begins to develop toward joeyhood. Tomorrow will surely be a better, wetter day.

Some mother hawks and owls are practical optimists, not only halving their brood when necessary but also eating them.

"Cannibalizing the victim serves the dual function of providing a timely meal and ensuring that there is one less mouth to feed," Dr. Forbes, the University of Winnipeg biologist, writes in his new book, "A Natural History of Families."

A hungry mother can be the stuff of nightmares — especially if it is the mother next door. Chimpanzees are exemplary mothers when it comes to caring for their own, said Sarah Blaffer Hrdy, a primatologist and the author of "Mother Nature: A History of Mothers, Infants and Natural Selection."

Unlike humans, Dr. Hrdy said, the apes never abandon or reject their young, no matter how diseased or crippled a baby may be. Yet because female chimpanzees live in troops with other nonrelated females, a ravenous, lactating mother feels little compunction about killing and eating the child of a group mate. "It's a good way to get lipids," Dr. Hrdy said.

As meal plans go, cannibalism can be no-muss, no-fuss. A mother nurse shark has two uteri in which her babies develop, safe from the ocean's predators. But the nurse shark is not a mammal, and she has no placenta. How to feed her fetal fish? On the fins and flesh of fellow fetal fish.

The mother incubates as many as 20 eggs per womb. The eggs hatch and start to grow, and when their jaws are sufficiently mature, they commence feeding on one another. By gestation's end, just one sharklet emerges from each uterine chamber.

Extracting nutrients from one's offspring need not be fatal, though. Among ants of the rare genus Adetomyrma, Dr. Forbes writes, "queens chew holes in their larvae and then consume the oozing fluid," a practice that explains why the insects, found in Madagascar, are known as Dracula ants. The sampled larvae recover and mature into ants, but they bear lifelong scars of their early bloodletting.

There are voracious mothers and vampiric mothers, and then there are phantom mothers. In the annals of mammaldom, the maximal minimalist of a mother must surely be the rabbit. Only recently have scientists studied rabbit behavior closely enough to appreciate what a marvel of efficiency a breeding rabbit is, said Robyn Hudson of the National University of Mexico.

Rabbits live together in complex burrows, where an expecting female will build a little nest and line it with grass and fur that she plucks from her flank. When she is ready to give birth, she enters the chamber and in less than eight minutes plops out 10 pups, "like peas in a pod," Dr. Hudson said.

Without bestowing on the litter so much as a single welcoming lick, the mother hops back out, closes up the entrance and leaves the helpless, furless newborns to huddle among themselves in the dark. Over the next 25 days, the mother will return to the nest for a mere two minutes a day, during which she crouches over the pups and they frantically nurse.

"Her milk is under high pressure, and it's almost squirted into their mouths," Dr. Hudson said. "You can see them visibly expand, like little grapes."

Two minutes are up, and she's out of there. On Day 26, she abandons them completely, and the bunnies must crawl from the nest and make their way in the world on their own.

The mother rabbit may seem awfully cold for a warmblood, but her aloofness makes sense. Rabbits are a highly popular prey, and many predators will pursue them into their burrows. To keep the fox from the nursery door, the mother rabbit shuns the room. Her absence may not make her pups' hearts grow fonder, but it may keep those hearts thumping a little longer.

Sunday, May 07, 2006

Saturday in the Park with Lloyd

At least 20 species of warbler have been seen in Central Park during the last two days. Lloyd Spitalnik sent photographs of two beauties. He writes:

Here are two Cinco de Mayo birds. Both were at Tanner's Spring.

Black-Throated Green Warbler

Blue-winged Warbler
Photos by Lloyd Spitalnik - May 5, 2006