New book chronicles four polar research expeditions: about penguins

Photo Credit: Chris Linder/WHOI

A picture by photographer Chris Linder of Adélie penguins from his 2007 trip to Ross Island for a story about the work done by penguin scientist David Ainley, which was included in Linder's recent book about polar research called "Science on Ice."

Embedded with scientists

New book chronicles four polar research expeditions

By Peter Rejcek, Antarctic Sun Editor

Posted January 27, 2012

 

Chris Linder has taken part in two dozen research expeditions over the last decade, many of them to the polar regions.

But Linder is not a scientist per se, though he earned a master’s degree from the Massachusetts Institute of Technology and Woods Hole Oceanographic Institution Joint Program in oceanography. That background has served him well as an expedition photographer whose work has appeared in books and magazines, such as Geo, Nature’s Best, Outdoor Photographer and Wired.

He recently published a book about four of his adventures to the Arctic and Antarctic in a book called Science on Ice (University of Chicago Press 2011), as part of an outreach project originally funded by the National Science Foundation .

Photo Credit: Mike Carlowicz/WHOI

Chris Linder with McMurdo Station in the background.

The four chapters of the book focus on a particular expedition, each written by a different science journalist. The first chapter features researcher David Ainley , who studies Adélie penguins in the Ross Sea region. Linder and science writer Hugh Powell  visited Ainley in November-December 2007, capturing images from McMurdo Station , Cape Royds and Cape Crozier. 

Linder recently answered a few questions from The Antarctic Sun about his new book and a more recent project about one of Antarctica’s lesser-known seabirds, the predatory skua.

1. Science on Ice features four research expeditions that you accompanied, along with a science writer, as part of a grant from the National Science Foundation for the International Polar Year . What made you choose to highlight those four particular projects, especially the one in Antarctica about Adélie penguins?

I chose those four particular expeditions to showcase the broad diversity of environments (Ross Island, the Greenland Ice Sheet, Bering Sea, Arctic Ocean) and disciplines (biology, engineering, glaciology, geology, chemistry, physics) that encompass polar science. On our trip to McMurdo Station, we chose to highlight David Ainley’s penguin science research for a few reasons. First, Adélie penguins are iconic — they are one of those species that people immediately associate with Antarctica. In terms of the science, Dr. Ainley is also an Antarctic icon (Ainley Peak, on Ross Island, is named after him). His team’s long-term study of Adélie penguins was a natural fit for our outreach project.

Photo Credit: Chris Linder/WHOI

Scientist Grant Ballard holds a tagged Adélie penguin.

Photo Credit: Chris Linder/WHOI

Jean Pennycook, left, and David Ainley mend a net.

Photo Credit: Chris Linder/WHOI

An Adélie penguin steps onto a scale.

2. How does your training as an oceanographer help you as a photographer while on assignment?

Having a science background gives me a distinct advantage when photographing fieldwork. I understand how long it takes to get a grant funded and how precious every second of field time is on an expedition. I carefully research each expedition’s logistics and science goals so that I know exactly what is going to happen, when, and why. I never ask scientists to change their activities to suit my images. Instead, I make sure that I am always ready for the action, even if that means working all night or waiting hours to document a unique science event. The science team appreciates my hands-off approach. This makes them more comfortable around the camera, and it’s easier for me to capture candid, behind-the-scenes moments.

3. Since 2002, you have photographed two dozen science expeditions, including 14 to the polar regions, no doubt working closely with many of the researchers you’ve photographed. What have you learned about the world of science by embedding yourself with your subjects for what can be weeks at a time? I know from my experiences that I’ve always been impressed with their commitment and tireless work ethic.

The scientists I photograph are my heroes. Aside from their determination and drive, the other quality that stands out to me is their creativity. Whether it’s dealing with logistical snafus, a broken instrument, or weather delays, researchers always come up with creative solutions to unexpected problems in the field.

4. Aside from the book, you did a number of outreach activities as part of the IPY grant. Would you talk about some of the creative ways you communicated polar research to the public?

One of the most enriching, but stressful, things we did on the Live from the Poles project was to facilitate a series of live calls from the science teams to audiences at museums, classrooms, and radio programs across the U.S. I still remember the sleepless nights I spent worrying about if the satellite phone connection would actually work. But listening to the insightful questions from kids and adults at the venues always reminded me of the value of this direct interaction.

5. You received a second grant from the NSF in 2010 under its Antarctic Artists and Writers Program . Your subject: the South Polar skua, which took you back to the Ross Sea region. Why a project about a relatively obscure, gull-like bird that likes to prey on penguins? And what do you hope to produce from that project?

On my first visit to Cape Royds and Cape Crozier, I was amazed by the teamwork and intelligence the skuas displayed as they robbed Adélie penguins of their eggs and chicks. After I returned home, I picked up a copy of Euan Young’s book Skua and Penguin: Predator and Prey, which explains in detail the research done on this topic. Surprisingly (to me), their observations revealed that the skuas acted more like scavengers than predators — essentially, they were eating the eggs and chicks that wouldn’t have survived anyway. I decided to write an Artists and Writers proposal to photograph the life history and behavior of the skuas at Cape Crozier, Ross Island. I spent six weeks photographing the birds, and was lucky enough to witness a wide range of behavior, including a penguin disturbing a skua nest and a skua pair feeding their chick. The story was shot as a first-look agreement with National Geographic magazine, and is still pending publication.

6. Anything you’d like to add?

Photographing these expeditions, with all of the stress, sleepless nights, and cold fingers, has been the hardest but most exhilarating job of my life. But the polar bears and penguins don’t make my job extraordinary; the people do. The scientists who kindly invited me to join their expeditions, the crews of the ships and field camps who kept me alive and happy, and the readers of the Polar Discovery website who sent in insightful questions and comments all reminded me why I was out there: to tell the stories of science on ice.

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Satellites Track Health of Seal, Penguin Populations in Antarctica

• Source: The Antarctic Sun
• Posted Saturday, February 18, 2012

A satellite image shows chinstrap penguin colonies at Baily Head, Deception Island, in 2003. The white patches are the colonies. Researchers are using high-resolution imagery shot from satellites to find, count and assess the population health of penguin and seal colonies around the Antarctic. Photo Credit: (c)DigitalGlobe Inc.; Image provided by National Geospatial-Intelligence Agency Commercial Imagery Program

Peter Rejcek, Antarctic Sun Editor: Penguins from outer space. Sounds like the title of some new B-movie science fiction film starring Vin Diesel. But polar researchers are increasingly using high-resolution imagery shot from orbiting satellites to find, count and assess the population health of penguin and seal colonies around the Antarctic.

"The satellite imagery is the most important advancement in my field since satellite tagging. I think it's an absolute game-changer," said Heather Lynch, an assistant professor at Stony Brook University involved in a long-term census survey of brushtail and crested penguins around the Antarctic Peninsula.

"Suddenly, we know what we don't know," Lynch explained. "We can look through the imagery and find colonies that we never knew existed, and look at population changes at colonies that were either inaccessible because of their location or they were impossible to census because of their size."

Lynch is an active user and advisory member of the Polar Geospatial Center (PGC), based at the University of Minnesota. PGC has access, through the National Geospatial-Intelligence Agency, to commercial satellite imagery with half-meter resolution -- about the breadth of a man's shoulders. The National Science Foundation-funded center provides high-resolution imagery and maps for U.S. Antarctic Program research and operations.

The main point of contact for all those users is Michelle LaRue, a research fellow at PGC whose interest in wildlife ecology has segued nicely with the remote sensing work. She has collaborated closely with Antarctic researchers involved in studying the polar region's most iconic animals, including Weddell seals and emperor penguins.

LaRue was the lead author on a paper published last year in the journal Polar Biology that argued that satellite imagery is a reliable way to assess seal abundance and population trends. She counted seals in pictures in collaboration with a research group from Montana State University (MSU) that conducts an annual population census of Weddell seals in McMurdo Sound around an area called Erebus Bay.

"The counts are highly correlated, which basically means what we're seeing in the satellite images is representative of what's on the ground at the same general time," said LaRue, who is working on a PhD in conservation biology at the University of Minnesota.

Robert Garrott, principal investigator for the MSU team, along with Jay Rotella, also a professor in MSU's Ecology Department, said the collaboration is beneficial to both sides.

"We can ground truth and help refine Michelle's algorithms and her ability to actually count seals on the ice," he said. In turn, the satellite technology and associated methodology will help the project expand beyond Erebus Bay without chartering an expensive research vessel.

"We can start asking questions about seal population and ecology over larger spatial scales without all the logistic support," Garrott said.

Lynch is certainly a believer in the technology. She and colleagues have a paper in press with Polar Biology outlining their methodology to use satellites to survey colonies of Adelie, chinstrap and gentoo penguins around the Antarctic Peninsula. The latter species is thriving as the Antarctic Peninsula region warms, while the other two are in steep decline. The paper also includes work on a crested penguin known as a macaroni, with a prominent yellow crest that looks like long, wild eyebrows.

Detailed counts of the penguins around the peninsula are inherently more difficult than the seal census. The large, dark bodies of the Weddell seals stand out starkly on the white sea ice. The terrain on the islands around the peninsula, on the other hand, is generally dark and snow-free in the summer months where the birds breed and raise their young.

A combination of extensive fieldwork and familiarity with each species' ecology helped with interpretation of the satellite pictures, according to Lynch, a co-principal investigator on the Antarctic Site Inventory program, which was started nearly 20 years ago by Ron Naveen, head of the nonprofit science and education organization Oceanites Inc.

"The remote sensing stuff is pretty incredible," Naveen said. "We're not quite putting our on-the-ground work out of business, which I'm happy about because I really enjoy doing it, but it's really an amazing supplement to what we've been up to for many years."

The imagery is also a valuable tool to the group's fieldwork, which spans more than 140 locations around the Antarctic Peninsula. "We were able to find penguins that were not on maps previously," Lynch noted. "It's going to make the time we spend in the field much more efficient."

Satellites have been around for more than 50 years, beginning with the launch of Sputnik I by the former Soviet Union in 1957. But it's probably only been within the last five years or so that pictures from space have been good enough for this sort of ecological research.

In fact, one of the first papers published on the topic was in 2007 in Polar Biology, about estimating relative abundance of emperor penguin colonies in the Ross Sea.

Paul Ponganis, a medical doctor and marine biologist at the University of California-San Diego's Scripps Institution of Oceanography, was a co-author on that paper, along with Gerald Kooyman, an emeritus professor at Scripps. Kooyman had gotten an exploratory grant from NSF in 2000 to test the feasibility of using satellite pictures to census emperor penguin colonies.

Ponganis said there are still a number of hurdles to overcome before satellites replace the aerial surveys that he and colleagues have conducted at seven emperor penguin colonies around the Ross Sea for the last 20 years or so.

For instance, it's still difficult to differentiate shadows from the black back of an emperor. Emperors stand vertically on the ice where they breed, not horizontally like a seal, which also causes some challenges. And the world's largest penguin also tends to congregate in tight huddles.

Still, Ponganis is optimistic. "I think that will be the future -- the satellite," he said.

Lynch agreed that there are still obstacles associated with the imagery, particularly around the Antarctic Peninsula, where clouds often obscure the region, making 90 percent of the imagery unusable. Weekly shots of Zavodovski Island in the South Sandwich Islands over a five-month period produced only one cloud-free scene.

But she boldly predicts that in five to 10 years scientists will be able to monitor every penguin colony in the Antarctic, from a handful of birds to groups that are a million strong.

"I think it's going to completely change the way we do penguin science in the Antarctic," she said.

Indeed, the British Antarctic Survey (BAS) made headlines in 2009 when it announced researchers had used satellite images to detect the light brown stain of emperor penguin guano on the sea ice. The imagery came from the Landsat Image Mosaic of Antarctica (LIMA), which seamlessly stitched together satellite photos of Antarctica acquired between 1999 and 2004.

The BAS study found 38 colonies from the guano stains, four more than were thought to exist. Ten were new colonies, while six previously known colonies either had disappeared or could not be found. A half-dozen colonies had relocated more than 10 kilometers away from their last-known position.

Such data are key to wildlife conservation issues, LaRue said.

Currently, emperor penguins are a species of "least concern," according to the International Union for Conservation of Nature and Natural Resources (IUCN). But some scientists have argued environmental changes and human impact from activities like industrial fishing are causing problems. A paper in 2009 published in the journal Proceedings of the National Academy of Sciences predicted emperors could be on the brink of extinction by the end of the century.

"There are lots of locations where there have never been counts, so the current estimate based on all of those sporadic, insufficient data is not that great," LaRue noted. "By being able to do this, we can actually see every single colony we know about and have a little bit better estimate of how many there are. You can't tell if they're going up and down if you don't know how many there are.

"That's the conservation issue: We don't really know how many there are, so how can you say if they're doing fine or not?" she added.

Such is the case of a chinstrap colony on Deception Island in the South Shetland Islands. A single satellite image from January 2003 compared to one from January 2010 shows dramatic changes are under way, according to Lynch.

"You can see in the imagery how a penguin colony collapses," she said. "You look at those two images and there's absolutely no question that there's something serious, seriously wrong going on with the chinstraps.

"It's concerning and scientifically exciting to be able to document those kinds of changes," Lynch added. "Moving forward, we'll be able to put together some amazing timelines."

NSF-funded research in this article: Paul Morin, University of Minnesota, Award No. 1043681; Robert Garrott, Jay Rotella, and Donald Siniff, Montana State University, Award No. 0635739; William Fagan and Heather Lynch, University of Maryland College Park, Award No. 0739515; Ron Naveen, Oceanites Inc., Award No. 0739430; Paul Ponganis, University of California-San Diego Scripps Institution of Oceanography, Award No. 0944220.

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Winged Dinosaur Archaeopteryx Dressed for Flight

Berlin specimen of Archaeopteryx: Paleontologists have long thought that Archaeopteryx fossils, including this one discovered in Germany, placed the dinosaur at the base of the bird evolutionary tree. (Credit: Museum für Naturkunde Berlin)

ScienceDaily (Jan. 24, 2012) — Since its discovery 150 years ago, scientists have puzzled over whether the winged dinosaur Archaeopteryx represents the missing link in birds' evolution to powered flight. Much of the debate has focused on the iconic creature's wings and the mystery of whether -- and how well -- it could fly.

Some secrets have been revealed by an international team of researchers led by Brown University. Through a novel analytic approach, the researchers have determined that a well-preserved feather on the raven-sized dinosaur's wing was black. The color and parts of cells that would have supplied pigment are evidence the wing feathers were rigid and durable, traits that would have helped Archaeopteryx to fly.

The team also learned from its examination that Archaeopteryx's feather structure is identical to that of living birds, a discovery that shows modern wing feathers had evolved as early as 150 million years ago in the Jurassic period. The study, which appears in Nature Communications, was funded by the National Geographic Society and the U.S. Air Force Office of Scientific Research.

"If Archaeopteryx was flapping or gliding, the presence of melanosomes [pigment-producing parts of a cell] would have given the feathers additional structural support," said Ryan Carney, an evolutionary biologist at Brown and the paper's lead author. "This would have been advantageous during this early evolutionary stage of dinosaur flight."

The Archaeopteryx feather was discovered in a limestone deposit in Germany in 1861, a few years after the publication of Charles Darwin's On the Origin of Species. Paleontologists have long been excited about the fossil and other Archaeopteryx specimens, thinking they place the dinosaur at the base of the bird evolutionary tree. The traits that make Archaeopteryx an evolutionary intermediate between dinosaurs and birds, scientists say, are the combination of reptilian features (teeth, clawed fingers, and a bony tail) and avian features (feathered wings and a wishbone).

The lack of knowledge of Archaeopteryx's feather structure and color bedeviled scientists. Carney, with researchers from Yale University, the University of Akron, and the Carl Zeiss laboratory in Germany, analyzed the feather and discovered that it is a covert, so named because these feathers cover the primary and secondary wing feathers birds use in flight. After two unsuccessful attempts to image the melanosomes, the group tried a more powerful type of scanning electron microscope at Zeiss, where the group located patches of hundreds of the structures still encased in the fossilized feather.

"The third time was the charm, and we finally found the keys to unlocking the feather's original color, hidden in the rock for the past 150 million years," said Carney, a graduate student in the Department of Ecology and Evolutionary Biology, studying with Stephen Gatesy.

Melanosomes had long been known to be present in other fossil feathers, but had been misidentified as bacteria. In 2006, coauthor Jakob Vinther, then a graduate student at Yale, discovered melanin preserved in the ink sac of a fossilized squid. "This made me think that melanin could be fossilized in many other fossils such as feathers," said Vinther, now a postdoctoral researcher at the University of Texas-Austin. "I realized that I had opened a whole new chapter of what we can do to understand the nature of extinct feathered dinosaurs and birds."

The team measured the length and width of the sausage-shaped melanosomes, roughly 1 micron long and 250 nanometers wide. To determine the melanosomes' color, Akron researchers Matthew Shawkey and Liliana D'Alba statistically compared Archaeopteryx's melanosomes with those found in 87 species of living birds, representing four classes: black, gray, brown, and a type found in penguins. "What we found was that the feather was predicted to be black with 95 percent certainty," Carney said.
Next, the team sought to better define the melanosomes' structure. For that, they examined the fossilized barbules -- tiny, rib-like appendages that overlap and interlock like zippers to give a feather rigidity and strength. The barbules and the alignment of melanosomes within them, Carney said, are identical to those found in modern birds.

What the pigment was used for is less clear. The black color of the Archaeopteryx wing feather may have served to regulate body temperature, act as camouflage or be employed for display. But it could have been for flight, too.

"We can't say it's proof that Archaeopteryx was a flier. But what we can say is that in modern bird feathers, these melanosomes provide additional strength and resistance to abrasion from flight, which is why wing feathers and their tips are the most likely areas to be pigmented," Carney said. "With Archaeopteryx, as with birds today, the melanosomes we found would have provided similar structural advantages, regardless of whether the pigmentation initially evolved for another purpose."

Contributing authors include Vinther, Shawkey, D'Alba, and Jörg Ackermann from Carl Zeiss.

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Story Source:

The above story is reprinted from materials provided by Brown University.

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Journal Reference:

1. Ryan M. Carney, Jakob Vinther, Matthew D. Shawkey, Liliana D'Alba, Jörg Ackermann. New evidence on the colour and nature of the isolated Archaeopteryx feather. Nature Communications, 2012; 3: 637 DOI: 10.1038/ncomms1642

Brown University (2012, January 24). Winged dinosaur Archaeopteryx dressed for flight. ScienceDaily. Retrieved January 26, 2012, from http://www.sciencedaily.com­ /releases/2012/01/120124113036.htm

Happy New Year! from Penguinology

Dino-Chicken???

Dino-Chicken: Wacky But Serious Science Idea of 2011

Stephanie Pappas, LiveScience Senior Writer

Date: 27 December 2011 

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Evolution in reverse: Could this chicken become a dinosaur? CREDIT: sanddebeautheil, Shutterstock View full size image

Paleontologist Jack Horner has always been a bit of an iconoclast. In the 1970s, Horner, the curator of paleontology at the Museum of the Rockies in Bozeman, Mont., and his friend Bob Makela discovered a Maiasaura nesting site, painting the first picture of dinosaurs as doting moms and dads. He's also been at the forefront of research suggesting that dinosaurs were fast growing and warm-blooded.

But Horner's newest idea takes iconoclasm to a new level. He wants, in short, to hatch a dinosaur.

Or something very much like one, at least. Horner, who served as a technical advisor for the "Jurassic Park" movies, has no illusions that the technique in that movie — extracting dino DNA from mosquitoes in amber — would work. DNA degrades too quickly, for one thing. Dinosaur DNA has proved impossible to extract from actual dinosaur bones, never mind blood-sucking insects.

"If you actually had a piece of amber and it had an insect in it, and you drilled into it, and you got something out of that insect and you cloned it, and you did it over and over and over again, you'd have a room full of mosquitoes," Horner said in a February 2011 TED Talk in Long Beach, Calif. TED, or Technology, Entertainment and Design, is a nonprofit focusing on "ideas worth spreading."

So Horner has another idea: Use the living dinosaurs among us to recreate creatures dead for millions of years. Anyone who's seen "Jurassic Park" knows that birds are dinosaurs, part of the evolutionary line containing those toothy Velociraptors. What's less known is that organisms carry their evolutionary history with them. Human embryos, for example, have temporary tails, which are absorbed by the body during development. Rarely, babies are born with vestigial tails, the result of scrambled genetic processes that prevent the tail from getting re-absorbed. These evolutionary remnants are called atavisms.

Enough atavisms have been discovered in birds to make the idea of "reverse-engineering" a dinosaur out of, say, a chicken possible, Horner says. You wouldn't be adding anything to the bird to make it more dinosaurlike; all the ingredients are in its DNA. Horner's goal is to figure out how to wake up those ingredients.

LiveScience talked with Horner about his "chickenosaurus" plan and what sort of dinosaur he'd like to keep as a pet.

LiveScience: What was the genesis of this chickenosaurus idea?

Horner: Knowing that birds descended from dinosaurs and knowing the changes that occur from dinosaurs to birds, we know that the changes that did occur occurred because of genetics.
A friend of mine, Hans Larsson at McGill University, was studying some of these changes and looking into how it was that dinosaurs lost their tails in the transformation from dinosaurs to birds. They also transformed their arms from a hand and an arm to a wing. I got to thinking, if he discovered the genes that were responsible for both of those transformations, we could just simply reverse evolution and reactivate the tail, and possibly make a hand back out of the wing.
And then what we would have by doing those two things, you'd actually take a bird and turn it into an animal that looked a lot like one of the meat-eating dinosaurs. It seemed like a good idea.

LiveScience: What kind of animal would chickenosaurus be? 

Horner: It's still a chicken. It's a modified chicken. You'd really have to mess with the DNA to make it something different.
The most important thing is that you cannot activate an ancestral characteristic unless the animal has ancestors. So if we can do this, it definitely shows that evolution works.

LiveScience: You've mentioned in the past that you see this dino-chicken as a teaching tool to help people understand evolution. Do you see that working?

Horner: Of course. You bet. There are people who are misinformed, and there are people who are uninformed [about the validity of evolution]. If people are uninformed, this will probably get through to them. If they've been misinformed and don't mind being misinformed, then they probably will continue to be misinformed.

LiveScience: Either way, it'd be a pretty awesome thing to take into a classroom.

Horner: Yes, it would. Exactly.

LiveScience: Starting with a chicken, how close could we really get to what a dinosaur looked like?

Horner: We're working with an animal that has all the right stuff. It's more about subtle changes, adding a tail or fixing a hand or possibly adding teeth, what we would think of as being relatively simple changes rather than messing with physiology or something like that.
A bird is really a dinosaur, so we're pretty sure that the breathing apparatus of a bird evolved from the breathing apparatus of a dinosaur, and is therefore completely different than a mammal. The physiology of a bird is evolved from a dinosaur and not from a mammal, so it's not like we're trying to take a mammal and turn it into a dinosaur.

LiveScience: Would chickenosaurus teach us anything about dinosaurs we can't learn from fossils?

Horner: It's not really about understanding dinosaurs at all. Once we learn what certain genes do and how to turn them on and turn them off, then we have great potential of solving some medical mysteries. There are a lot of ways to think about this, but it's not really about dinosaurs other than solving Hans Larsson's problem of figuring out how birds lost their tails. [Tales of 10 Vestigial Limbs]

LiveScience: What do you see as the biggest challenge of making chickenosaurus happen?

Horner: The biggest challenge, first off, is to find the genes. We know that in the development of a tail, there are a variety of things that have to happen, so there are a couple of ways to possibly go about this.
One, as we know, when a chicken embryo is developing in the egg, just like basically all animals, the embryo actually for a time has a tail and then the trail re-absorbs. So if we could find the gene that re-absorbs the tail and not allow that gene to turn on then we could potentially hatch a chicken with a tail.
The other method would be simply to go in and discover what Hox genes [the genes that determine the structure of an organism] might be responsible for actually adding tail vertebrae, and then to see if we could add some, either by manipulating the Hox genes or by using temperature. There have been some experiments done showing that adding heat will add a vertebra here or there.

LiveScience: Where are you in this process now?

Horner: Right now, mostly I'm looking for a postdoctoral researcher. An adventurous postdoc who knows a lot about developmental biology and a little bit about birds and has done some work about chickens to work in our lab here in Bozeman.
Me, I just go through the literature, looking for anything that might give me a clue as to what genes might be responsible for tail absorption or tail growth or something that might help me with hands.

LiveScience: The comparisons to "Jurassic Park" are easy to make, but have you ever seen the movie "The Birds?" Do we really want chickens with extra teeth and claws running around?

Horner: You can't really compare it to either movie. First off, you can go out in the Serengeti and there are all kinds of animals that will eat you, but if you're driving around in your Jeep, you're just fine. The lions and cheetahs and leopards are not going to try to get into your Jeep when there are plenty of plant-eaters out there to eat that aren't inside of a metal cage.
That's the funny thing about "Jurassic Park," right? All these dinosaurs want to eat people no matter how hard they are to get.
So we don't have to worry about "Jurassic Park," because that's just fiction. Animals don't act that way. They're not vengeful. And birds aren't vengeful either.

LiveScience: So if you could bring a dinosaur back — the real thing, not a modified chicken — what species would you choose?

Horner: A little one. A little plant-eater.

LiveScience: No T. rex for you?

Horner: Would you make something that would turn around and eat you? Sixth-graders would do that, but I'd just as soon make something that wouldn't eat me. And you could have it as a pet without worrying about it eating the rest of your pets.

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Source:LiveScience

Merry Christmas from Penguinology!

Wishing that all your dreams will come true this year at Christms!

~~~wiinterrr

Do penguins communicate under water?

Do penguins communicate under water?

Written by Chris Thomas  

Friday, 23 December 2011  

 

“Very little is known about underwater acoustic communication in birds so any findings are important.”—Dr Parsons. Flickr: Andy Field

IT’S a question being asked by the Centre for Marine Science and Technology’s Research Fellow Miles Parsons, who is collaborating with Perth Zoo to find out.

While penguins can be noisy on land, Dr Parsons says research into the sounds they make, if any, underwater has been extremely limited.

“Given some species of penguins spend significant time underwater and dive to depths where visual communication is reduced, it’s feasible that sound provides an alternative source of communication,” Dr Parsons says.
“The reasons behind any communication could be identifying, locating and catching food, warning signals, exploration, socialising and being antagonistic—but at the moment this is speculation.”

As part of his research Dr Parsons placed underwater noise loggers that include a hydrophone or underwater microphone, hard drive and battery pack, in Perth Zoo’s fairy penguin (Eudyptula minor novaehollandiae) enclosure.

The devices recorded all noise for nine out of every 15 minutes.

“If the penguins produce any sounds underwater we will be able to record them,” Dr Parsons says.
“From there, we would be able to investigate whether these sounds are used to communicate between the penguins or if they serve some other function (involuntary noise).

“Very little is known about underwater acoustic communication in birds so any findings are important.”
Dr Parsons says his research is in a controlled zoo environment and communication in the wild may be different.

Environmental noise could also affect penguin sounds and its perception underwater.

“There’s a lot of possible ways ambient, whether a biotic or man-made, noise can affect the sound production, transmission and reception,” he says.

“These can range from a behavioral change in the penguins with a disturbance causing movement away from the noise source and a reduced production of sound by penguins.”

“There’s also the masking of calls—ambient noise at the same frequency as any penguin calls will reduce the range at which a recipient can detect a call, or possibly the sound of an approaching predator.

“Particularly intense signals may cause temporary or permanent damage to the hearing.”

Perth Zoo’s penguin colony has been transferred to Melbourne Zoo while renovations take place and is due back before Christmas.

“What I am hoping to do is re-record when the penguins return from Melbourne and they re-acquaint themselves with their environment,” Dr Parsons says,

“Then we might hear some communication.”

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Dinosaurs With Killer Claws Yield New Theory About Evolution of Flight

New research from Montana State University reveals how dinosaurs like Velociraptor and Deinonychus used their famous killer claws, leading to a new hypothesis on the evolution of flight in birds. (Credit: Illustration by Nate Carroll)

ScienceDaily (Dec. 14, 2011) — New research from Montana State University's Museum of the Rockies has revealed how dinosaurs like Velociraptor and Deinonychus used their famous killer claws, leading to a new hypothesis on the evolution of flight in birds.

In a paper published Dec. 14 in PLoS ONE, MSU researchers Denver W. Fowler, Elizabeth A. Freedman, John B. Scannella and Robert E. Kambic (now at Brown University in Rhode Island), describe how comparing modern birds of prey helped develop a new behavior model for sickle-clawed carnivorous dinosaurs like Velociraptor.

"This study is a real game-changer," said lead author Fowler. "It completely overhauls our perception of these little predatory dinosaurs, changing the way we think about their ecology and evolution."

The study focuses on dromaeosaurids; a group of small predatory dinosaurs that include the famous Velociraptor and its larger relative, Deinonychus. Dromaeosaurids are closely related to birds, and are most famous for possessing an enlarged sickle-claw on digit two (inside toe) of the foot. Previous researchers suggested that this claw was used to slash at prey, or help climb up their hides, but the new study proposes a different behavior.

"Modern hawks and eagles possess a similar enlarged claw on their digit 2's, something that hadn't been noted before we published on it back in 2009," Fowler said. "We showed that the enlarged D-2 claws are used as anchors, latching into the prey, preventing their escape. We interpret the sickle claw of dromaeosaurids as having evolved to do the same thing: latching in, and holding on."

As in modern birds of prey, precise use of the claw is related to relative prey size.

"This strategy is only really needed for prey that are about the same size as the predator; large enough that they might struggle and escape from the feet," Fowler said. "Smaller prey are just squeezed to death, but with large prey all the predator can do is hold on and stop it from escaping, then basically just eat it alive. Dromaeosaurs lack any obvious adaptations for dispatching their victims, so just like hawks and eagles, they probably ate their prey alive too."

Other features of bird of prey feet gave clues as to the functional anatomy of their ancient relatives; toe proportions of dromaeosaurids seemed more suited for grasping than running, and the metatarsus (bones between the ankles and the toes) is more adapted for strength than speed.

"Unlike humans, most dinosaurs and birds only walk on their toes, so the metatarsus forms part of the leg itself," Fowler said. "A long metatarsus lets you take bigger strides to run faster; but in dromaeosaurids, the metatarsus is very short, which is odd."

Fowler thinks that this indicates that Velociraptor and its kin were adapted for a strategy other than simply running after prey.

"When we look at modern birds of prey, a relatively short metatarsus is one feature that gives the bird additional strength in its feet," Fowler continued. "Velociraptor and Deinonychus also have a very short, stout metatarsus, suggesting that they had great strength but wouldn't have been very fast runners."

The ecological implications become especially interesting when dromaeosaurids are contrasted with their closest relatives: a very similar group of small carnivorous dinosaurs called troodontids, Fowler said.

"Troodontids and dromaeosaurids started out looking very similar, but over about 60 million years they evolved in opposite directions, adapting to different niches," Fowler said. "Dromaeosaurids evolved towards stronger, slower feet; suggesting a stealthy ambush predatory strategy, adapted for relatively large prey. By contrast, troodontids evolved a longer metatarsus for speed and a more precise, but weaker grip, suggesting they were swift but probably took relatively smaller prey."

The study also has implications for the next closest relatives of troodontids and dromaeosaurids: birds. An important step in the origin of modern birds was the evolution of the perching foot.

"A grasping foot is present in the closest relatives of birds, but also in the earliest birds like Archaeopteryx," Fowler said. "We suggest that this originally evolved for predation, but would also have been available for use in perching. This is what we call 'exaptation:' a structure evolved originally for one purpose that can later be appropriated for a different use."

The new study proposes that a similar mechanism may be responsible for the evolution of flight.

"When a modern hawk has latched its enlarged claws into its prey, it can no longer use the feet for stabilization and positioning," Fowler said. "Instead the predator flaps its wings so that the prey stays underneath its feet, where it can be pinned down by the predator's bodyweight."

The researchers suggest that this 'stability flapping' uses less energy than flight, making it an intermediate flapping behavior that may be key to understanding how flight evolved.

"The predator's flapping just maintains its position, and does not need to be as powerful or vigorous as full flight would require. Get on top, stay on top; it's not trying to fly away," Fowler said. "We see fully formed wings in exquisitely preserved dromaeosaurid fossils, and from biomechanical studies we can show that they were also able to perform a rudimentary flapping stroke. Most researchers think that they weren't powerful enough to fly; we propose that the less demanding stability flapping would be a viable use for such a wing, and this behavior would be consistent with the unusual adaptations of the feet."

Another group of researchers has proposed that understanding flapping behaviors is key to understanding the evolution of flight, a view with which Fowler agrees.

"If we look at modern birds, we see flapping being used for all sorts of behaviors outside of flight. In our paper, we are formally proposing the 'flapping first' model: where flapping evolved for other behaviors first, and was only later exapted for flight by birds."

The researchers believe their new ideas will open multiple new lines of investigation into dinosaur paleobiology, and the evolution of novel anatomical structures.

"As with other research conducted at the Jack Horner paleo lab, we're looking at old paleontological questions with a fresh perspective, taking a different angle," Fowler said. "Just as you have to get beyond the idea that feet are used just for walking, so we are coming to realize that many unusual structures in modern animals originally evolved for quite different purposes. Revealing the selection pathways that mold and produce these structures helps us to better understand the major evolutionary transitions that shaped life on this planet."

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Story Source:

The above story is reprinted from materials provided by Montana State University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Denver W. Fowler, Elizabeth A. Freedman, John B. Scannella, Robert E. Kambic. The Predatory Ecology of Deinonychus and the Origin of Flapping in Birds. PLoS ONE, 2011; 6 (12): e28964 DOI: 10.1371/journal.pone.0028964

Montana State University (2011, December 14). Dinosaurs with killer claws yield new theory about evolution of flight. ScienceDaily. Retrieved December 16, 2011, from http://www.sciencedaily.com­ /releases/2011/12/111214171541.htm

100 years on, Antarctic science going strong

It's one of the primary drivers of human activity on the continent

Jefferson Beck / NASA

A NASA aircraft, part of the agency's IceBridge mission, banks over an ice shelf jutting out from western Antarctica during an October 2011 data-gathering flight.

 

By Andrea Mustain

OurAmazingPlanet

12/14/2011 

 

eek, dozens of brave revelers — the prime minister of Norway among them — are converging on the South Pole to celebrate the historic trek of Norwegian explorer Roald Amundsen, the first human to set foot there on Dec. 14, 1911.

Yet in an ironic twist, some might argue that it is the runner-up in the grueling contest whose legacy has proved more lasting.

British explorer Robert Falcon Scott, who reached the pole a month after Amundsen, died on his return march, unable to escape the tightening noose of the Antarctic winter. And although his oft-maligned tactics proved, in part, to be his undoing, Scott's insistence on bringing scientists on his expedition — at great cost to himself — helped spark a tradition of scientific inquiry in Antarctica that endures to this day, according to Ross MacPhee, curator at the American Museum of Natural History in New York, and author of the book, "Race to The End: Amundsen, Scott, and the Attainment of the South Pole" (Sterling Innovation, 2010).
"Every scientist working in Antarctica today owes Scott something," MacPhee told OurAmazingPlanet in September.

Science is now one of the primary drivers of human activity on the continent.
Each year, when the perpetual daylight of austral summer begins, droves of scientists descend on Antarctica to study its biology, drill deep into its ice, and send airplanes soaring overhead to image what lies underneath its glaciers.
Nearly 30 countries operate more than 80 research stations around the continent, according to 2009 numbers from the Council of Managers of National Antarctic Programs.
A flurry of work is now under way on and around the continent.

Courtesy of Charles Leski, Leski Auctions.

Robert Falcon Scott in the expedition's well-stocked hut. 

 

Charismatic fauna 

Some scientists come to study the unique crowds of marine life that gather near the nutrient-rich waters off the Antarctic coast in the comparatively balmy summer. Penguins may be the most beloved of the local animal pantheon, but studying these birds is nothing like a Disney movie.
"Penguins are not cuddly at all. They're really very strong and very feisty, and they don't like to be picked up, which we try not to do," said David Ainley, a marine ecologist who has been studying Adélie penguins in Antarctica since the late 1960s.

For decades, Ainley, now with the California-based ecological consulting firm H.T. Harvey & Associates, has researched why penguin populations are changing; some colonies have grown, others have shrunk. He said he's interested in answering a very basic question about life on our planet — how do animals cope with their environment? — and that penguins are the ideal research subject.
"They're fairly large so you can put instruments on them and record their behavior," Ainley told OurAmazingPlanet just hours before he boarded a plane headed south.

Dr. Robert Ricker, NOAA / NOS / ORR

Don't ask these guys to tap dance. Adelie penguins in Antarctica.

In addition, he said, they're pretty easy to find. "Penguins are very visible," Ainley said. "In the Antarctic they don't have any place to hide. They don't live in burrows, and it's daylight all the time."

Biological time trip 

While Ainley and his team spend their days on the rocky slopes of Antarctic islands, other scientists spend the austral summer on ships. David Barnes, with the British Antarctic Survey, spoke with OurAmazingPlanet from the RRS James Ross, a research vessel parked near the Antarctic Peninsula, the long finger of land that points toward South America.

Barnes said that his research focuses on trying to unlock the secrets of Antarctica's icy past, specifically how the reach of the massive West Antarctic Ice Sheet has changed from age to age. Scientists know it has been larger than it is now, and some suspect it has been smaller than it is now, but anything more exact is difficult to pin down.

"The problem is that every time there's an ice age it's wiped out everything — so we don't really know where the last ice sheet got to," Barnes said. But there is another way to peek into the Antarctic's past: "Where we can't get good signals from glaciology or geology, biology has a cunning way of stepping in," he said.

Eric Rignot, JPL 

 

This is an aerial, close-up view of the floating section and ice front of Pine Island glacier, November 2002.

Barnes looks at the genetic makeup of sea creatures around western Antarctica to determine how long populations have been isolated from one another by the ice.
"Genetics preserve a connection between species and populations, so by looking around Antarctica at various depths we can get an idea of whether that area used to be underneath an ice sheet," Barnes said.
That information can, in turn, help scientists figure out how the West Antarctic Ice Sheet behaved in climates past, and how it might behave in our warming world.

Ice life 

Still other scientists will spend the austral summer living on the ice itself. Robert Bindschadler, a glaciologist and scientist emeritus with NASA, along with a small team of researchers, will spend six weeks sleeping in small tents on a floating plain of ice — the Pine Island Glacier ice shelf — the outlet of one of the largest and fastest moving glaciers in Antarctica.
Ice shelves, which ring the continent, appear to be a key player in the increasing and alarming rate at which glaciers in the West Antarctic Ice Sheet are melting and raising sea levels in recent years, Bindschadler said. But getting direct observations of how this is happening is a challenge. Satellite imaging and data provide some details, but the continent is remote, and its long, brutal winter permits scientists to work there for only about three months a year, [ Stunning Photos of Antarctic Ice ]

Observations indicate that comparatively warm ocean water is lapping away at the ice shelves, which, as they weaken, allow glaciers to slide into the sea at a faster and faster clip — yet the direct mechanisms remain hidden from view.
"Satellites have taken us really far, but they can't give us the answers to what's going on underneath," Bindschadler said. To that end, his team will spend its days drilling several  holes through nearly a third of a mile (500 meters) of ice to drop sensors into the sea below to measure variations in temperature and currents.
Some scientists conduct their research from the air, working aboard planes equipped with imaging technology that can peer beneath the ice.   NASA's IceBridge project focuses on the western half of the continent, while other international collaborations focus on the far larger yet more stable eastern half.

Ice work if you can get it 

Other research must be done on the ground. Scientists are drilling deep into the ice to collect signatures of past climate trapped inside, or looking for microbes that dwell in it. The race to drill down to the more than 200 freshwater lakes that pepper the continent is another tantalizing quest..

Some researchers work in Antarctica because the frigid continent, free of a native human population or meddling flora and fauna, provides a kind of natural laboratory.
"In most ecosystems you have plants all over the place, and they do a lot of things to complicate the system," said Byron Adams, a professor at Brigham Young University who studies the nematodes and other tiny creatures that are found in the few patches of ice-free soil in the Antarctic.

Rob Jones, National Science Foundation

 

Flags fly outside McMurdo Station, one of three United States research stations in Antarctica and the largest.

Still other researchers take advantage of the high altitude and clear air to peer through telescopes into distant space and the early universe.
At about 1.5 times the size of the United States, Antarctica has plenty of scientific real estate to go around.
At the heart of much of the research is the question of how the continent's ice is responding to climate change. Antarctica is home to some of the most dramatic effects of climate change seen anywhere on Earth, from melting glaciers to increasing winds to warming temperatures. The Antarctic Peninsula has warmed several times faster than the global average rate.

"We're asking really fundamental questions about how ecosystems respond to a changing climate, and ultimately the goal is to be able to make predictions about this," Adams told OurAmazingPlanet.
Despite the challenges — bone-chilling winds, constant sunlight, extreme isolation and ever-changing weather — many scientists said working in Antarctica is worth the hardship and the long hours spent packing as much work into an expedition as possible. Although it's not for everyone, they cautioned, the work can be deeply satisfying, breeding a sense of camaraderie that can last a lifetime.

"When you're out in the deep field, and you're only living with what you brought, and the plane turns and leaves, that's the Antarctica I prefer," Bindschadler said. "You really are in a different world."

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Seabirds: Climate Differences Have Less Impact On Transmission of Blood Parasites Than Expected

Close neighbourly relations: Like these gentoo penguins on the Falkland Islands, seabirds often breed in dense colonies. The very conditions that provide the birds with protection against predators, promote the spread of ticks and other bloodsuckers which can transmit diseases. This population was found to be free of blood parasites, however. (Credit: © MPI for Ornithology)

ScienceDaily (Dec. 12, 2011) — Seabirds often live in large colonies in very confined spaces. Parasites, such as fleas and ticks, take advantage of this ideal habitat with its rich supply of nutrition. As a result, they can transmit blood parasites like avian malaria to the birds. Scientists from the Max Planck Institute for Ornithology in Radolfzell and a team of international colleagues have investigated whether this affects all seabirds equally, and whether climate conditions, the habitat or particular living conditions influence infection with avian malaria. They discovered that most seabirds are free of malaria parasites; however, some groups, especially frigatebirds, are particularly common hosts to malaria parasites.

 

Although there is a link between warmer temperatures and increased rates of infection, not all tropical seabirds are infected. The risk of infection within a habitat increases for species with longer fledgling periods and specific types of breeding grounds.

Seabirds exist in locations as varied as the Antarctic and tropical oceans. However, they all need land for breeding grounds. In order to protect themselves against predators or due to a lack of suitable breeding places, they often form large dense colonies. As a result, they provide blood suckers like fleas, ticks and bird lice -- wingless insects which live in the plumage and feed on the birds' feathers and blood -- with a plentiful supply of food and a habitat. Therefore, these insects can arise in large numbers in such colonies. These small pests also survive well in cold climates such as that found in the Subantarctic, and are not particularly specialised in their choice of food, something the researchers know from their own painful experience.

Other blood-sucking insects, like mosquitoes, are present mainly in warmer climates, as found in the tropical breeding grounds. Because mosquitoes are among the main transmitters of the Plasmodium genus of avian malaria, the researchers from the Max Planck Institute for Ornithology and their colleagues from Spain, France, Mexico and the US investigated whether infections of avian malaria differed in seabirds from cold and warm marine areas. To do this, they analysed blood samples from seabirds from different regions for parasitic infections using genetic methods.

"We were surprised that the climate differences had less impact on the transmission of blood parasites than expected," says Petra Quillfeldt. "More vectors live in warmer climates; therefore, we would have expected to find a higher rate of infection in tropical locations. We discovered, however, that different species living on the same island under the same climate conditions can display very different rates of infection." The researchers defined several seabird groups that regularly carry malaria parasites. Frigatebirds were found to be particularly affected here, as all five species of this tropical seabird family are frequently infected.

"Of five seabird species present in the seabird community on Christmas Island in the tropical Indian Ocean, only the Christmas Island frigatebirds were found to be malaria hosts. Over half of the island's frigatebirds were affected and, moreover, with three genetically different malaria lines of the subgenera Haemoproteus and Parahaemoproteus, one of which was a completely new strain. As opposed to this, tropical birds and three species of gannet on the same island were not infected at all," explains Petra Quillfeldt.

Furthermore, the scientists have failed to find any blood parasite infections in other seabird groups, such as skuas and auks. Their research has led to the conclusion that the likelihood of infection depends, among other things, on the lifestyle of the birds: species with longer fledgling periods and hole-nesters are particularly severely affected.

This is the first study of this kind to examine seabirds in all climate zones. It has shown that different factors can influence infection with malaria parasites. The study also raised new questions: The researchers would now like to gain a better understanding of the life cycles of the malaria parasites and their transmitters, as well as discover which mechanisms are responsible for susceptibility to infection among the different species.

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Story Source:

The above story is reprinted from materials provided by Max-Planck-Gesellschaft.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal References:

1. Petra Quillfeldt, Elena Arriero, Javier Martínez, Juan F Masello, Santiago Merino. Prevalence of blood parasites in seabirds - a review. Frontiers in Zoology, 2011; 8 (1): 26 DOI: 10.1186/1742-9994-8-26
2. Merino, S., Hennicke, J., Martínez, J., Ludynia, K., Masello, J.F. & Quillfeldt, P. Infection by Haemoproteus parasites in four species of frigatebirds and description of Haemoproteus (Parahaemoproteus) valkiūnasi sp. nov. (Haemosporida, Haemoproteidae). Journal of Parasitology, 2011 Oct 12

Max-Planck-Gesellschaft (2011, December 12). Seabirds: Climate differences have less impact on transmission of blood parasites than expected. ScienceDaily. Retrieved December 15, 2011, from http://www.sciencedaily.com­ /releases/2011/12/111212092655.htm

Antarctic study digs for clues to penguin past

By James Borrowdale

Wednesday Dec 14, 2011

Photo / James Borrowdale

Adelie penguins live in the coldest environment on earth.

Happy Feet's distant relatives might one day become victims of climate change.
Experts warn the effects of a warming climate could affect the small ecological niche in which Adelie penguins reside.
Scientists from the University of Auckland and Italy's University of Pisa are in Antarctica to search for clues about Adelie penguins' evolutionary past, and what this reveals about how they will respond to climate change.

Professor Carlo Baroni, professor of geomorphology at the University of Pisa, said penguins lived in the coldest environment on earth and if the temperature warmed, penguins couldn't migrate to a colder climate.
"If global warming increases and affects the Antarctic regions, penguins have no other place to go, so they must adapt or die."
The team left Scott Base this week for a month of collecting samples from two penguin rookeries. Over many years of habitation Adelie penguins leave layers of accumulated bones, eggshells, feathers, nests, and guano. This presents scientists with the opportunity to dig through the levels and gather DNA from long-dead penguins.

"It is very similar to an archaeological approach. We mark squares of one metre by one metre then layer by layer we excavate it and collect samples."
Professor Baroni, now on his 14th trip to Antarctica, said his team had previously uncovered samples as old as 40,000 years.
"We are at the limits of the capability of radiocarbon dating."
Auckland University's Yvette Wharton said the limited ecological niche of Adelie penguins made them excellent subjects for studying adaptive evolution. As their niche changed, she said, the penguins would have to change with it.

"As we are getting climate change occurring there is going to be quite a specific effect on their potential ecological niche. We're squishing them."
She said they would learn of past climatic changes, how the colony sizes had changed, and how the penguins had evolved to meet these new conditions.
"You can then use that as a model to see the types of things that might happen to an organism with environmental changes."

ADELIE PENGUINS

* Males and females come on land for just a few months each summer to breed and raise their chicks - a task mastered by "tag-team parenting" in minding the egg.
* Males arrive first to find the best spot and build a nest. When the females arrive, the males serenade their prospective mates with a sound described as a cross between a donkey and a stalled car.
* Females look for the fattest male they can find, as their partner must spend the first two weeks sitting on the eggs without any chance to go in search of food.

source

How penguins 'time' a deep dive

 

8 December 2011 

 

The penguins beat their wings an average of 237 times on each dive

Emperor penguins "time" their dives by the number of flaps they can manage with their wings. 

This is according to a new study published in the Journal of Experimental Biology.

It aimed to show how the birds reached the "decision" that it was time to stop feeding and return to the surface to breathe.

Tracking the birds revealed that they flapped their wings, on average, 237 times on each dive.

The study was led by Dr Kozue Shiomi, from the University of Tokyo, Japan.

Dr Shiomi and his team think that the penguins' decision to end their foraging dive and return to the surface is constrained by how much power their muscles can produce after every pre-dive breath. This "flying" motion propels the birds forwards, allowing them to swim quickly through the water, gulping fish.

Using data collected from diving penguins on previous field trips, the team analysed the patterns of more than 15,000 penguin dives.
They studied 10 free-ranging birds and three birds that were foraging through a hole in the ice.

          EMPEROR PENGUIN FACTS

• Emperor penguins are the largest species of penguin, standing at over one metre tall and weighing an average of 40kg
• In the bitter cold, males and females choose mates relatively quickly, pairing off and "flirting" with special neck-stretching displays
• The males incubate eggs through the fierce Antarctic winter while females feed themselves up to provide for their chicks in the spring

Timing the penguins' dives revealed that free-ranging birds began their final ascent to the surface about 5.7 minutes into their dive. But penguins diving through the ice hole often dived for longer before performing a U-turn and returning up through the same ice hole. 

Examining the acceleration patterns of the penguins as they dived, the team managed to calculate that all the birds used, on average, 237 wing flaps before starting their ascent.

"We suggest", the team concluded in their paper, "that the decision [to return] was constrained not by elapsed time, but by the number of strokes and, thus, perhaps cumulative muscle work."

source