Tuesday, December 17, 2013

Traffic Jams Lend Insight Into Emperor Penguin Huddle

Emperor penguins maintain the tight huddle that protects them from the harsh conditions of an Antarctic winter with stop-and-go movements like cars in a traffic jam, a new study has shown. (Credit: Daniel Zitterbart)
Dec. 16, 2013 — Emperor penguins maintain the tight huddle that protects them from the harsh conditions of an Antarctic winter with stop-and-go movements like cars in a traffic jam, a new study has shown.
By using a mathematical model that recreated the positions, movements and interactions of individual penguins in a huddle, researchers have revealed that an individual penguin only needs to move 2 cm in any direction for its neighbour to react and also perform a step to stay close to it. 
These movements then flow through the entire huddle like a travelling wave and play a vital role in keeping the huddle as dense as possible to protect the penguins from the cold; the wave also helps smaller huddles merge into larger ones.

The results have been published today, 17 December, in the Institute of Physics and German Physical Society's New Journal of Physics and are accompanied by a video abstract. An advanced set of videos can be viewed here -- http://www.youtube.com/playlist?list=PLx-sGUtkV82eZJHWNyJ4uxPCBtb1GlWgw
In a previous study, the same group of researchers studied time-lapse videos and showed that instead of remaining static, penguins in a huddle actually move every 30-60 seconds, causing surrounding penguins to move with them.

Co-author of the study Daniel Zitterbart, from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), said: "Our previous study showed how penguins use travelling waves to allow movement in a densely packed huddle, but we had no explanation as to how these waves propagate and how they are triggered."

To investigate this, the researchers used a mathematical model, which has previously been used to study traffic jams, and compared the results with an analysis of video recordings of a real-life penguin huddle.
Unlike a traffic jam, the researchers found that the waves of movements in a penguin huddle can originate from any single penguin and can propagate in any direction as soon as a sufficient gap, known as a "threshold distance," develops between two penguins.

This threshold distance was estimated to be around 2 cm, which is twice the thickness of a penguin's compressive feather layer, suggesting the penguins touch each other only slightly when standing in a huddle without compressing the feather layer so as to maximize huddle density without compromising their own insulation.

"We were really surprised that a travelling wave can be triggered by any penguin in a huddle, rather than penguins on the outside trying to push in," continued Zitterbart. "We also found it amazing how two waves, if triggered shortly after each other, merged instead of passing one another, making sure the huddle remains compact."

The emperor penguin is the only vertebrate species that breeds during the severe conditions of the Antarctic winter. At this time of year temperatures can get as low as -50°C and winds can reach speeds of up to 200 km/h.

To cope with the harsh conditions, the male penguins form dense huddles, often consisting of thousands of individuals, to maintain their body temperatures. Unlike other species of penguin, the male emperors are solely responsible for incubating their single egg during the winter, covering it in an abdominal pouch above their feet while the female returns to sea to feed.

Story Source:
The above story is based on materials provided by Institute of Physics, via EurekAlert!, a service of AAAS.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. R C Gerum, B Fabry, C Metzner, M Beaulieu, A Ancel, D P Zitterbart. The origin of traveling waves in an emperor penguin huddle. New Journal of Physics, 2013; 15 (12): 125022 DOI: 10.1088/1367-2630/15/12/125022

Institute of Physics (2013, December 16). Traffic jams lend insight into emperor penguin huddle. ScienceDaily. Retrieved December 17, 2013, from http://www.sciencedaily.com­ /releases/2013/12/131216204020.htm

Friday, December 13, 2013

2 Profs Head to Antarctica for Penguin Studies

Penguin study

Posted: Dec 12, 2013
  San Diego, California News Station - KFMB Channel 8 - cbs8.com
SAN DIEGO (CBS 8) - Funding is a dilemma researchers always face. Luckily for one local scientist, private funding paved the way from San Diego to the South Pole, with the benefit of using new technology that's cutting down on time in the field with better accuracy. In this week's earth 8 we bring you part 2 of the science behind this penguin study.
Senior research scientist Dr. Brent Stewart hopes to answer many important questions about several penguin species living on the South Pole.

When you're surrounded by hundreds of thousand of birds, the only way to get a better count is to fly high above them. As we showed you in part one of this series, a drone-like aircraft was used to collect more precise scientific data.
"What I really like about it is it can be a stable platform rather than flying over very quickly, we can hover. We can quickly move it in one direction, spin it around to get different perspectives," Stewart said. "But it's going to take another month, two months to count each bird at the two colonies. The big ones, the king penguins St. Andrews Bay, Salsbury Plains, they're probably 200,000 to 300,000 birds at each one of those colonies."

Although it looks crowded, Stewart says some colonies are not doing as well as others.
"Adelie penguins on the peninsula, we know that their populations are changing very rapidly as the climate there changes very rapidly. But other species are coming in and doing very well, so there are local colonies which are sustaining and are vital and other colonies are declining," he said.

Aside from a variable climate, penguins will always have natural predators.
"For Antarctic penguins, leopard seals are predators, they eat them. Particularly in the peninsula, killer whales, I think the ultimate predators are parasites which they're always dealing with. Infectious disease is a key issue in their population, biology. But it's really leopard seals and killer whales are their primary predators other than humans used to be.

"We're starting to plan for the next season next year for the Antarctic trip. Locally it's elephant seal season that's coming up in December, so I spend a lot of time out in San Nicholas & San Miguel Islands to study populations there, and we're trying to use the same kind of tools to help us with that," Stewart said.



Citadal professor headed to Antarctica to study penguins

  • Posted: Thursday, December 12, 2013
A rockhopper penguin warms its young chick and guards against predators during Citadel professor Paul Nolan's 2006 research trip to the Falkland Islands.
Penguins are the proverbial canary in a coal mine when it comes to gauging climate change, says Citadel biology professor Paul Nolan.

So he packed his freezing-weather gear and is headed to Antarctica Friday to study them.

Nolan, who studies animal behavior focusing mostly on birds, said he's been studying penguins for more than a decade, including taking several trips south of the equator to observe the waddling black and white creatures in their natural habitats.

He'll be working on the penguin study with Oxford University professor Tom Hart. People can learn more about the work, at PenguinLifelines.org.

Nolan, who also runs the nonprofit group CharlestonAudubon.org,said The Citadel Foundation gave him a $3,000 grant to help him with his research. He expects to share much of what he experiences with his students in future classes.

Jay Dowd, the foundation's chief executive officer, said Nolan's research is one of many ground-breaking projects conducted on campus by faculty, graduate students, and cadets to which the foundation contributes.
Nolan said it's important to go to Antarctica because "ongoing climate change is most pronounced at the poles." In Antarctica, there's been a 5- to 6-degree temperature increase in the past 100 years," he said.

The researchers plan to study the birds in two major ways. They will collect and analyze feathers that drop from the birds, he said, because feathers contain stress hormones, an indicator of environmental change.
They also will place cameras in penguin colonies that snap pictures every hour. The cameras will remain in place for about a year, he said, then researchers will go back and collect the cards from the cameras and study the photos. "The big idea behind this is that we want to monitor the behavior without bothering the birds."

A huge number of photographs will be collected, Nolan said, and members of the public can volunteer to help annotate them. The photographs will be available on April 25, which is International Penguin Day, he said.

Nolan said his unique role in the project is to study the color and color changes of the birds, especially in their beaks and feet. Color can reveal a great deal about an animal's health, he said.

Temperatures in Antarctica this time of year range from 0 to 20 degrees, he said, but he's ready for the cold.
The research team will travel on a cruise ship, and take Zodiac boats to various penguin colonies each day, he said. It's very difficult to find a way to travel in that part of the world, he said, but cruise ships work well. The researchers will make some presentations on penguins to other travelers, he said.


A Penguin's Tale: Diet Linked to Breeding Failure

Dec. 12, 2013 — A study on a Victorian penguin colony has revealed new insight into the link between seabird diet and breeding success.

In a study published in Functional Ecology, Nicole Kowalczyk and Associate Professor Richard Reina of Monash University's School of Biological Sciences, in collaboration with Andre Chradia from Phillip Island Nature Parks, studied Melbourne's St Kilda little penguin colony over two years.

They detailed how changes to prey abundance or food sources influenced reproductive success, tracking the penguins' nesting and feeding behaviour during the 2010 and 2011 breeding season.

Given previous data had shown that the colony fed mainly on anchovy which accounted for up to 78 per cent of their diet between years 2004 and 2008, the researchers predicted that changes in abundance would impact on the reproductive success of the colony -- but they were surprised to find the little penguins were resilient to changing conditions only if alternative prey such as sardines could be found.

Ms Kowalczyk said breeding failure in seabirds has been associated with declines in prey abundance, and the quality and diversity of prey -- but identifying which aspect of diet was responsible was challenging.
"The St Kilda little penguin colony has a short foraging range and displays narrow dietary diversity so this gave us the unique ability to identify how changes in food supply influence their reproduction," Ms Kowalczyk said.

"We found that a sharp decline of anchovy in 2010 had a negative impact on little penguin reproduction. However, in 2011, despite the relatively low anchovy abundance, their breeding success was extremely high.
"We believe the decrease of anchovy itself was not the only cause for low breeding success in 2010 but in combination with the scarcity of alternative prey. Our results show that little penguins are resilient to changes in their preferred prey but their ability to adapt to these changes is limited by the availability of alternative prey species."

Ms Kowalczyk said understanding seabird diet was integral to their conservation and management.
"Our results highlight that resource abundance and the availability of a variety of prey are critical factors in enabling this inshore seabird to adjust to changes in environmental conditions and fluctuations in their primary source of prey," Ms Kowalczyk said.

"Dietary changes have been linked to population declines and provide information about foraging conditions, particular prey species and foraging locations that require protection."

Story Source:
The above story is based on materials provided by Monash University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. Nicole D. Kowalczyk, Andre Chiaradia, Tiana J. Preston, Richard D. Reina. Linking dietary shifts and reproductive failure in seabirds: a stable isotope approach. Functional Ecology, 2013; DOI: 10.1111/1365-2435.12216

Monash University (2013, December 12). A penguin's tale: Diet linked to breeding failure. ScienceDaily. Retrieved December 13, 2013, from http://www.sciencedaily.com­ /releases/2013/12/131212103351.htm

Sunday, November 24, 2013

The mystery of Captain Scott's penguin eggs

, Thursday 21 November 
Specimens for scientific study can be extremely difficult to collect, as Captain Robert Falcon Scott learned on his last expedition to Antarctica.
During the past few days, I've been sorting and organising the photographs from my recent trip to London, and shared the above image on twitter. In this photograph, you see a rather large eggshell with a more-or-less rectangular window cut into the shell. According to the museum label that accompanies this specimen, this is one of three emperor penguin eggs that had been collected -- fresh -- by Captain Scott on his last expedition to Antarctica.

But because I had copied the tweet to the Natural History Museum, and because a knowledgeable person was monitoring their twitter feed, I soon learned that the museum tag accompanying this egg shell was not-quite-correct: in fact, Bill Wilson, Apsley Cherry-Garrard and Henry "Birdie" Bowers actually collected this egg in 1911. These three men were part of Captain Scott's last Antarctic expedition.

But that is only a small part of the story. Since emperor penguins breed in the middle of the Antarctic winter, this meant the explorers had to hike 70 miles from Scott's base camp on Ross Island to the penguin breeding colony on Cape Crozier, locate and collect these eggs during the worst possible time: not only was it perpetually dark, but they faced extreme cold, powerful winds and intense blizzards. Why would three well-educated humans knowingly subject themselves to the worst weather imaginable on Earth to collect five fresh penguin eggs -- two of which they accidentally broke during their return journey? Were these guys mad?

These three men might have been mad, but the reason for their five-week-long expedition was not. Penguin eggs were important at that time because they were thought to be integral to confirming a scientific hypothesis popularised by Ernst Haeckel. This hypothesis, famously known as "ontogeny recapitulates phylogeny", proposed that development from a fertilised egg through adulthood re-enacts evolution via stages that resemble the ancient ancestors that gave rise to that particular species:

"Ontogeny recapitulates phylogeny." George Romanes' 1892 copy of Ernst Haeckel's controversial -- allegedly fraudulent -- embryo drawings. Romanes' version is often attributed incorrectly to Haeckel. [Romanes, G. J. (1892). Darwin and After Darwin. Open Court, Chicago.] This image is in the public domain due to its age.

This was a controversial hypothesis, but at least some scientists of that time thought they could watch the evolution of bird feathers from reptilian scales by documenting various stages of embryonic development of a primitive bird. At the time, penguins were thought to be the most primitive of birds (actually, this is not true) so this was the rationale for collecting penguin eggs for study instead of, say, chicken eggs.

Eventually, these eggs were added to the collection at the Natural History Museum. Twenty-three years after they had been collected -- after the "ontogeny recapitulates phylogeny" hypothesis had been discredited -- a study was published by zoologist CW Parsons, who concluded that "they did not greatly add to our understanding of penguin embryology."

Although Wilson, Cherry-Garrard and Bowers miraculously managed to return to Scott's base camp with three of the five eggs intact, perhaps most remarkable aspect of this adventure was the mystery that the intrepid explorers had missed: they never noticed that each bird's single precious egg, which was balanced on the parent's feet, was actually being incubated by the father.
Here's a video of Douglas Russell, curator of eggs at the Natural History Museum, telling us a little more of the story about this particular egg:

The pencil drawing of the penguin embryo (above right) is by Dorothy Thursby-Pelham.

NOTE [23 November 2013, Saturday, 0830]: this piece incorrectly stated that the NHM tag on this egg was incorrect. In fact, although captain Scott did not personally collect the penguin eggs, he did make it possible for this to happen by providing access to Antarctica and some information to Wilson, Cherry-Garrard and Bowers about the colony's location. This piece has been amended to correct that inaccuracy.

GrrlScientist can also be found here: Maniraptora. She's very active on twitter @GrrlScientist and sometimes lurks on social media: facebook, G+, LinkedIn, and Pinterest.


Saturday, November 23, 2013

A Heat Map Of Penguins Explains How They Stay Warm

Penguin heat map
courtesy Université de Strasbourg and Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
As if their home in Antarctica weren’t cold enough, emperor penguins allow their exteriors to drop at least 7°F below their surroundings. The change helps the penguins stay warm, a recent paper showed. When the outer layer of feathers radiates heat to the sky, it becomes colder than its immediate environment, so heat flows back in. The cycle keeps the temperature underneath the plumage constant—and the penguin alive.

This article originally appeared in the December 2013 issue of Popular Science.
This article originally appeared on Popular Science


Wednesday, November 13, 2013

Did Ancient Climate Change Spur Penguin Evolution?

Photo of a Gentoo penguin on Cuverville Island, Antarctica.
A cooling spell in Antarctica may have helped penguins diversify into the numerous species alive today, such as this Gentoo penguin. Photograph by Paul Souders, Corbis
Ker Than
for National Geographic
Published November 12, 2013

When did the earliest common ancestor of the penguins we know today first waddle the Earth, and why?

The question is surprisingly controversial, and may become more so with a new study suggesting a climate-change connection.

Possible dates for the last common ancestor of living penguins have differed by tens of millions of years. According to DNA evidence, the early ancestor lived some 40 million years ago, while fossil evidence puts the date closer to 10 million years ago.

Now a new genetic study, detailed in this week's issue of the journal Biology Letters, suggests that today's major penguin lineages began diverging from one another about 11 to 16 million years ago, and that their common ancestor first appeared 20 million years ago.

The study also suggests that a prolonged cooling spell in Antarctica may have helped spur penguins to diversify into the 18 species living today.

Reconciling Evidence

The new finding, based on more DNA points than past studies, helps reconcile the genetic and fossil evidence, explained study leader Sankar Subramanian, a postdoctoral student at Griffith University in Australia.

"For the first time we showed a more recent time of origin of penguins, which was in agreement with that based on morphological data," he said.

Intriguingly, the date that Subramanian's team estimates for the diversification of modern penguins coincides with a time 10 to 15 million years ago when scientists think Antarctica underwent a period of rapid cooling that covered the continent in ice.

"So we connected these two dots and speculated [about] a possible relationship," Subramanian said in an email. He cautioned, however, that he and his colleagues "don't have any proof for this connection, which is indeed hard to obtain."

A Mysterious Gap

Paleontologists have found penguin-like fossils dating as far back as 62 million years, tens of millions of years before the first ancestor of today's penguins emerged on the scene.

"The big gap between these two times raises questions like: What happened to the older lineages of penguins? What caused the extinction of all other older lineages? Could that be due to any change in Antarctic or global climate?" Subramanian said.

Subramanian said his team is planning to look next at the molecular signatures of penguins living in very different environments, from the tropical Galápagos Islands to the frozen Antarctic.

"This might reveal valuable information, such as how they could adapt to live in these diverse climates," he said.

Friday, October 18, 2013

Australian climate change researchers look to penguin poo

Climate change -- October 15, 2013

By: News Desk

If you're going to study the effects of climate change on a food chain, you have to look at how that food, ahem, ends up. Researchers from the Australian government's Antarctic Division will study the Antarctic food chain, specifically, the historical feeding habits of Adelie penguins and impacts of ocean acidification on phytoplankton and bacteria, the smallest building blocks of the southern continent's ecosystem, according to a report from AFP.

Seabird expert Barbara Wienecke will lead the survey as the team excavates ancient droppings to dertermine changes in the penguins' diets over time.

She explained the research to AFP:
"We will be digging down into the old soils formed from bird waste and looking for the remains of prey, such as fish ear-bones and squid beaks," said Wienecke.
"It is the first time this type of work has been done in the Davis region and we are hopeful of finding out whether Adelie diets changed in the past, for example, from krill to fish-based diets," she added.
"Gaining this knowledge can help manage Southern Ocean fisheries to avoid disrupting the Antarctic food chain."


Thursday, October 10, 2013

Longer Life for Humans Linked to Further Loss of Endangered Species

Endangered yellow eyed penguin. New Zealand has a high percentage of endangered birds. (Credit: © paradoxdes / Fotolia)
Oct. 9, 2013 — As human life expectancy increases, so does the percentage of invasive and endangered birds and mammals, according to a new study by the University of California, Davis.

The study, published in the September issue of Ecology and Society, examined a combination of 15 social and ecological variables -- from tourism and per capita gross domestic product to water stress and political stability. Then researchers analyzed their correlations with invasive and endangered birds and mammals, which are two indicators of what conservationist Aldo Leopold termed "land sickness," the study said.

Human life expectancy, which is rarely included among indexes that examine human impacts on the environment, surfaced as the key predictor of global invasions and extinctions.

"It's not a random pattern," said lead author Aaron Lotz, a postdoctoral scholar in the Department of Wildlife, Fish and Conservation Biology when the study was conducted. "Out of all this data, that one factor -- human life expectancy -- was the determining factor for endangered and invasive birds and mammals."

The study analyzed data from 100 countries, which included roughly 87 percent of the world's population, 43 percent of global GDP per capita, and covered 74 percent of Earth's total land area.

Additional factors considered were agricultural intensity, rainfall, pesticide regulation, energy efficiency, wilderness protection, latitude, export-import ratio, undernourishment, adult literacy, female participation in government, and total population.
The findings include:
  • New Zealand, the United States and the Philippines had among the highest percentages of endangered and invasive birds.
  • New Zealand had the highest percentage of all endangered and invasive species combined, largely due to its lack of native terrestrial mammals. The study said that in the past 700 to 800 years since the country was colonized, it has experienced massive invasion by nonindigenous species, resulting in catastrophic biodiversity loss.
  • African countries had the lowest percentage of invasive and endangered birds and mammals. These countries have had very little international trade, which limits opportunities for biological invasion.
  • As GDP per capita -- a standard measure of affluence -- increased in a country, so did the percentage of invasive birds and mammals.
  • As total biodiversity and total land area increased in a country, so did the percentage of endangered birds. (Biodiversity in this context is not a measure of health but refers to the number of species in an area.)
Lotz said the study's results indicate the need for a better scientific understanding of the complex interactions among humans and their environment.

"Some studies have this view that there's wildlife and then there's us," said Lotz. "But we're part of the ecosystem. We need to start relating humans to the environment in our research and not leave them out of the equation. We need to realize we have a direct link to nature."

Story Source:
The above story is based on materials provided by University of California - Davis.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. Aaron Lotz, Craig R. Allen. Social-Ecological Predictors of Global Invasions and Extinctions. Ecology and Society, 2013; 18 (3) DOI: 10.5751/ES-05550-180315
University of California - Davis (2013, October 9). Longer life for humans linked to further loss of endangered species. ScienceDaily. Retrieved October 10, 2013, from http://www.sciencedaily.com­ /releases/2013/10/131009130122.htm

Wednesday, October 9, 2013

An ancient dinosaur-era bird turns out to have two tails

A prehistoric bird with two tails.
A reconstruction of a two-tailed 120-million-year-old Jeholornis.
Illustration courtesy Aijuan Shi
Dan Vergano
National Geographic
Published October 7, 2013

The early bird gets two tails? A 120-million-year-old bird sported a long tail and a second, unexpected tail frond, paleontologists suggest. The discovery points to a complicated evolutionary path for the tails we see in birds today.

One of the oldest known birds, Jeholornis, lived in what is today China, along with a trove of other feathered dinosaurs discovered in the region over the last decade. It was also thought to sport only a long fan-feathered tail at its back end. Now, however, paleontologists are claiming discovery of a second tail frond adorning the bird.

"The 'two-tail' plumage of Jeholornis is unique," according to the study, which was led by Jingmai O’Connor of the Chinese Academy of Sciences in Beijing. The report of the discovery of the tail frond was published in the Proceedings of the National Academy of Sciences.

Of 11 Jeholornis fossils that retain evidence of ancient plumage, 6 have signs of this frond of 11 feathers, which would have jutted above the bird's back at a jaunty, upright angle in a "visually striking" manner, according to the study.

Two-Tailed Display

"Clearly the display aspect of the frond would have been undeniable," says paleontologist Mark Norell, of the American Museum of Natural History in New York, who was not part of the study. "It calls to mind living birds, even peacocks, which display broad plumes of feathers."
In peacocks and other birds, such feathery features are more for attracting the attention of potential mates than for any functional purpose.

Since male birds today are the ones with the striking plumage, the authors suggest that perhaps only one sex of Jeholornis sported the eye-catching tail fronds.

Early Aviation Advantage?

Jeholornis is not thought to be directly related to modern birds, which seem to have evolved from a different line of early avians. The study authors suggest that the tail frond may have played a stabilizing role in the flight of these early birds and that if the arrangement of feathers had proven advantageous enough, modern birds might have evolved to sport such two-tailed features. They see the fronds as flattening to offer a streamlined appearance when the bird was in flight.

Other researchers aren't convinced the newly discovered tail frond played much of a role in aviation, however. "Feathering in the new specimens is quite interesting, but we have to remember it is a feature so far only known in one species," says University of Texas paleontologist Julia Clarke, who adds the frond wasn't seen in all the fossils.

"Thus, its implications for the origin of flight are unclear," she says. "It could have been a peculiarity of the one species, as the authors note." Perhaps more likely, she suggests the frond simply evolved as an easy-to-notice "sexual display" flaunted by these early birds.

Sunday, September 29, 2013

The Victory Squawk of the Little Blue Penguin

Apr. 03, 2012
by Kara Rogers
Little Penguin (Eudyptula minor) family exiting burrow, Bruny Island, Tasmania, Australia. Photo by Noodle snacks.

Victory is sweet, so much so that we often feel compelled to rejoice with a cry of triumph. For some animals, that cry not only announces a win to all those within earshot but also serves surprisingly complex social functions. Take, for instance, the call of the victorious little blue penguin (Eudyptula minor), which a recent study in the journal Animal Behavior revealed has a direct effect on the behavior of “social eavesdroppers” -- penguins who, from the safety of their burrows, assess the quality of fighting individuals based solely on their vocalizations.

Male little blue penguins are fierce defenders of their territories and frequently become engaged in flipper-slapping territorial disputes. At the conclusion of a scuffle, the winner celebrates with a so-called triumph display, in which he delivers a victory bray -- a distinctive squawk that according to the new study serves as a sort of warning signal to other males in the colony, potentially mitigating future confrontations for the winner and preventing embarrassing defeats for lesser male challengers.
Little blue penguins, which are the smallest penguins in the world, are social animals that use vocalization during activities such as courtship and foraging and as a way of announcing their arrival at their home burrows. However, while much is known about the various functions of many of the penguins' calls, the social significance of vocalization associated with victory calls had remained unclear.

To assess the impact of triumph brays on the behavior of eavesdropping penguins, the scientists played a recording of a vocal exchange and flipper-slapping fight between territorial males and then played recordings of both the victor's triumph call and the loser's call. They then measured the heart rates of eavesdroppers in response to the sounds using heart monitors hidden in artificial eggs that were placed in the penguins' nests. The team found that eavesdropping males' heart rates increased in response to the victor's call when compared with the loser's call. In addition, in simulated approach experiments in which the loser's or winner's call was played just outside the entrance of an eavesdropper's burrow, the scientists discovered that eavesdropping males challenged the loser's call with vocalizations of their own but fell silent when the triumph call was played.

Triumph displays and other forms of postconflict signaling have been documented in a variety of species, including birds such as the Canada goose (Branta canadensis), the greylag goose (Anser anser), and the bell shrike (Laniarius aethiopicus), as well as animals such as the green frog (Rana clamitans) and an insect known as the Wellington tree weta (Hemideina crassidens). Postconflict signaling in these species appears to function either as a form of advertising, in which the winner's display communicates his dominance to eavesdroppers, or as a form of intimidation, in which the winner's display serves to reduce the chance that the loser will initiate a future challenge. Thus, in many ways, by showing off a little after a victory, these animals are simply establishing their reputation as winners. In other words, they're behaving very much like humans.


Wednesday, September 18, 2013

Ten-Year Project Redraws the Map of Bird Brains

A revised map of the bird brain shows cortical areas organized in columns, as in mammals and humans. (Credit: Image courtesy of Duke University)

Sep. 17, 2013 — Explorers need good maps, which they often end up drawing themselves.

Pursuing their interests in using the brains of birds as a model for the human brain, an international team of researchers led by Duke neuroscientist Erich Jarvis and his collaborators Chun-Chun Chen and Kazuhiro Wada have just completed a mapping of the bird brain based on a 10-year exploration of the tiny cerebrums of eight species of birds.

In a special issue appearing online in the Journal of Comparative Neurology, two papers from the Jarvis group propose a dramatic redrawing of some boundaries and functional areas based on a computational analysis of the activity of 52 genes across 23 areas of the bird brain.

Jarvis, who is a professor of neurobiology at Duke, member of the Duke Institute for Brain Sciences, and a Howard Hughes Medical Institute investigator, said the most important takeaway from the new map is that the brains of all vertebrates, a group that includes birds as well as humans, have some important similarities that can be useful to research.

Most significantly, the new map argues for and supports the existence of columnar organization in the bird brain. "Columnar organization is a rule, rather than an exception found only in mammals," Jarvis said. "One way I visualize this view is that the avian brain is one big, giant gyrus folding around a ventricle space, functioning like what you'd find in the mammalian brain," he said.

To create different patterns of gene expression for the analysis, the birds were exposed to various environmental factors such as darkness or light, silence or bird song, hopping on a treadmill, and in the case of migratory warblers, a magnetic field that stimulated their navigational circuits.

The new map follows up on a 2004 model, proposed by an Avian Brain Nomenclature Consortium, also lead by Jarvis and colleagues, which officially changed a century-old view on the prevailing model that the avian brain contained mostly primitive regions. They argued instead that the avian brain has a cortical-like area and other forebrain regions similar to mammals, but organized differently.

"The change in terminology is small this time, but the change in concept is big," Jarvis said. For this special issue, the of Journal of Comparative Neurology commissioned a commentary by Juan Montiel and Zoltan Molnar, experts in brain evolution, to summarize the large amount of data presented in the studies by the Jarvis group.

One of the major findings is that two populations of cells on either side of a void called the ventricle are actually the same cell types with similar patterns of gene expression. Earlier investigators had thought of the ventricle as a physical barrier separating cell types, but in development studies led by Jarvis' post doctoral fellow Chun-chun Chen, the Duke researchers showed how dividing cells spread in a sheet and flow around the ventricle as they multiply.

The new map simplifies the bird cortex, called pallium, from seven populations of cells down to four major populations. Humans have five populations of cells in six layers.

Part of this refinement is simply that the tools are getting better, says Harvey Karten, a professor of neurosciences at the University of California-San Diego who proposed a dramatic re-thinking of bird cortical organization in the late 1960s. The best tools in that era were microscopes, specific cell stains and electrophysiology. Karten and colleagues are authors of a fourth paper in the special issue which announces a database of gene expression profiles of the avian brain containing some of the data that the Jarvis group used.

Jarvis said having a more specific map is necessary for properly sampling cell populations for gene expression analysis to do even more functional analysis of how the brain operates. As a next step, his team is considering doing an even more detailed bird map with "several hundred" genes rather than the 52 used to make this map.

Jarvis and colleagues are working now on a similar mapping of the crocodile brain with the ultimate goal of being able to say something about how dinosaur brains were organized, since both birds and crocs are descended from them. At a Society for Neuroscience conference in November, they'll be presenting some early findings from that project.

Though the specifics of this newest map may only be of interest within the bird research community, Jarvis said, it builds the awareness that birds can be a useful model for many questions about the human brain.

"Where does the mammalian brain come from?" Karten asks. "And what's the origin of these structures at the cellular and molecular level?" Some neuroscientists have argued that the mammalian cortex -- the one we have -- is something apart from the brains of other vertebrates. Jarvis and Karten now think vertebrate brains have more commonalities than differences.

That awareness is making birds an ever more useful model for questions about the human brain. "There are very few animal models where you can learn -- at the molecular level -- what's going on in vocal learning," Karten said. Birds are also being used as models for research on Parkinson's, Huntington's, deafness and other degenerative conditions in humans.

The work was supported by grants from Human Frontiers in Science Program, The National Science Foundation, NIMH (R01-MH62803), NIDCD (R01-DC007218), NIH ARRA Supplement 3DP10D000448-04S1 and the Howard Hughes Medical Institute.

Story Source:
The above story is based on materials provided by Duke University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal References:
  1. Erich D. Jarvis, Jing Yu, Miriam V. Rivas, Haruhito Horita, Gesa Feenders, Osceola Whitney, Syrus Jarvis, Electra R. Jarvis, Lubica Kubikova, Ana E. P. Puck, Connie Siang-Bakshi, Suzanne Martin, Michael McElroy, Erina Hara, Jason Howard, Henrik Mouritsen, Chun-Chun Chen, Kazuhiro Wada. A global view of the functional molecular organization of the avian cerebrum: Mirror images and functional columns. Journal of Comparative Neurology, 2013; DOI: 10.1002/cne.23404
  2. Chun-Chun Chen, Candace M. Winkler, Andreas R. Pfenning, Erich D. Jarvis. Molecular profiling of the developing avian telencephalon: regional timing and brain subdivision continuities. Journal of Comparative Neurology, 2013; DOI: 10.1002/cne.23406

Duke University (2013, September 17). Ten-year project redraws the map of bird brains. ScienceDaily. Retrieved September 18, 2013, from http://www.sciencedaily.com­ /releases/2013/09/130917093924.htm

How Birds Got Their Wings: Fossil Data Show Scaling of Limbs Altered as Birds Originated from Dinosaurs

Archaeopteryx lithographica, specimen displayed at the Museum für Naturkunde in Berlin. Believed to be a transitional species between theropod dinosaurs and birds, Archaeopteryx had longer forelimbs and shorter hind limbs than its ancestors. (Credit: By H. Raab (User:Vesta) (Own work) [CC-BY-SA-3.0 or GFDL], via Wikimedia Commons)

Sep. 17, 2013 — Birds originated from a group of small, meat-eating theropod dinosaurs called maniraptorans sometime around 150 million years ago. Recent findings from around the world show that many maniraptorans were very bird-like, with feathers, hollow bones, small body sizes and high metabolic rates.

But the question remains, at what point did forelimbs evolve into wings -- making it possible to fly?
McGill University professor Hans Larsson and a former graduate student, Alexander Dececchi, set out to answer that question by examining fossil data, greatly expanded in recent years, from the period marking the origin of birds.

In a study published in the September issue of Evolution, Larsson and Dececchi find that throughout most of the history of carnivorous dinosaurs, limb lengths showed a relatively stable scaling relationship to body size. This is despite a 5000-fold difference in mass between Tyrannosaurus rex and the smallest feathered theropods from China. This limb scaling changed, however, at the origin of birds, when both the forelimbs and hind limbs underwent a dramatic decoupling from body size. This change may have been critical in allowing early birds to evolve flight, and then to exploit the forest canopy, the authors conclude.

As forelimbs lengthened, they became long enough to serve as an airfoil, allowing for the evolution of powered flight. When coupled with the shrinking of the hind limbs, this helped refine flight control and efficiency in early birds. Shorter legs would have aided in reducing drag during flight -- the reason modern birds tuck their legs as they fly -- and also in perching and moving about on small branches in trees. This combination of better wings with more compact legs would have been critical for the survival of birds in a time when another group of flying reptiles, the pterosaurs, dominated the skies and competed for food.

"Our findings suggest that birds underwent an abrupt change in their developmental mechanisms, such that their forelimbs and hind limbs became subject to different length controls," says Larsson, Canada Research Chair in Macroevolution at McGill's Redpath Museum. Deviations from the rules of how an animal's limbs scale with changes in body size -- another example is the relatively long legs and short arms of humans -- usually indicate some major shift in function or behaviour. "This decoupling may be fundamental to the success of birds, the most diverse class of land vertebrates on Earth today."

"The origin of birds and powered flight is a classic major evolutionary transition," says Dececchi, now a postdoctoral researcher at the University of South Dakota. "Our findings suggest that the limb lengths of birds had to be dissociated from general body size before they could radiate so successfully. It may be that this fact is what allowed them to become more than just another lineage of maniraptorans and led them to expand to the wide range of limb shapes and sizes present in today's birds."

"This work, coupled with our previous findings that the ancestors of birds were not tree dwellers, does much to illuminate the ecology of bird antecedents." says Dr. Dececchi. "Knowing where birds came from, and how they got to where they are now, is crucial for understanding how the modern world came to look the way it is."

Funding for the research was provided by the Fonds de recherche du Québec -- Nature et technologies, the Canada Research Chairs program, and the National Sciences and Engineering Research Council of Canada.

Story Source:
The above story is based on materials provided by McGill University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. T. Alexander Dececchi, Hans C. E. Larsson. Body and Limb Size Dissociation at the Origin of Birds: Uncoupling Allometric Constraints Across a Macroevolutionary Transition. Evolution, 2013; 67 (9): 2741 DOI: 10.1111/evo.12150

McGill University (2013, September 17). How birds got their wings: Fossil data show scaling of limbs altered as birds originated from dinosaurs. ScienceDaily. Retrieved September 18, 2013, from http://www.sciencedaily.com­ /releases/2013/09/130917123613.htm

Sunday, September 8, 2013

Worldwide Researchers Flock to Penguin Meeting

Originally published on Fri September 6, 2013


This is SCIENCE FRIDAY. I'm Ira Flatow. Just about everybody loves penguins, right? They're funny on land. They're amazing underwater, and they're very photogenic, so they show up in lots of ads and movies. But beyond the screen, prospects for the birds are not entirely good. This week, over 200 researches from around the world met in the U.K. to talk penguins, from the prospects of conservation of species to how penguins are able to stay under water so long, to the properties of penguin poop.

Joining me now to talk about it is Peter Barham. He's a professional teaching fellow in physics at the University of Bristol. He's also the chair of the organizing committee for the Eighth International Penguin Conference, which wrapped up today. Welcome to SCIENCE FRIDAY.

PETER BARHAM: Good afternoon, I think it must be, Ira.

FLATOW: Thank you. First let me ask you: What's a physicist doing studying penguins?

BARHAM: Oh, physicists, of course, we turn our hands to anything. But I have had, through my wife, an obsession with penguins for quite some time. And a while back, must be - it was about 15, 16 years ago now, I went to the Third International Penguin Conference for fun and discovered that there were things to with tagging and marking and following penguins which a physicist's skills were helpful for, and got involved then, and it's since become a major part of my research career.

FLATOW: Yeah. You know, we see penguins in so many ads on TV and the movies, cute little fellows. We don't think of them as endangered at all, but they are, according to...

BARHAM: They are very much endangered, yes. There are 18 or maybe 19 species of penguin. It depends on how you do the genetics. and of those, all but three are listed on the IUCN red listed as being at least threatened, and three - no, four now are listed as being actually endangered. And of those, I would be surprised if any are still around at the end of this century.

FLATOW: Wow. And where is the endangerment coming from?

BARHAM: It's a mixture of causes. Principally, it is down to the inability of the penguins to find sufficient food in the localities where they're situated. Penguins, because when they're breeding and their raising young, have to go return to the colony where the young are, they can only swim for - depending on the species - one day or maybe three or four days before they have to return with food for the young.

And if there is no easily accessible food within that distance that they can find in the time, then they can't breed. So that's one of the major causes. Those, of course, are caused by the changing locations of fish because of a global change in ocean currents and the rising temperatures in the Antarctic of melting the ice, and also by the fact of where the fish are in large quantities is also where our fishing vessels are. And so there's competition with fisheries.

FLATOW: Wow. Is there some tool that the penguin research community really needs now?

BARHAM: There are lots of tools we need, and we've invested a lot of effort into managing to find great deal of information by remote sensing technologies. We had quite a lot of talks at the conference on using satellite imagery to locate penguin conferences(ph). But we still don't have a good technology for really understanding what they're doing on the longer trips away from the colonies between breeding seasons, when, actually, we know now that how well fed they are at the onset of breeding, then it has a great influence on how they breed. There's no technology which will last that long.

FLATOW: Because of the climate down there is so harsh.

BARHAM: People think of penguins coming from cold places. That's a fallacy. Penguins do breed all over the Southern Hemisphere, anywhere there is cold water. So there are penguins breeding in the Galapagos Islands - not many left, but they're there. And there actually are a few pairs of penguins that breed in the Galapagos Islands just north of the equator. Very few of those, probably three or four pairs in total.

But you'll find penguins breeding with their nest sites in the Atacama Desert in the west coast of Chile and Peru. You'll find penguins in Southern Africa. That's where I work, in around the Cape Town area, where the temperatures can easily reach 30 degrees. So the idea that penguins are limited to Antarctica is not true. And, in fact, the most endangered species are the temperate species, the species that are not in Antarctica.

FLATOW: So what's the course of action? How can - first, I guess you would have to get the public to realize how endangered they are.

BARHAM: That's a really key point: getting people involved and on all sides. And then the sort of measures you have to employ are things like habitat reconstruction, because we have effectively destroyed nearly all the penguin habitats in the temperate regions, because penguins live in sea bird colonies. Sea birds poop, and sea bird poop is guano, which is a fantastic fertilizer, and it's all being taken away. So they haven't got anywhere to nest any longer. So we have to put out artificial nests for them, and determining what the best sort of nest is.

That's one thing we can do. Other things we can do is try to influence fishery policy in those areas where penguins live, to sway the policymakers to ensure that the fishermen are not operating the same areas in direct competition with the penguins. And we know where the penguins - well, we have a good idea where the penguins are foraging, and we actually put tracking devices on them so we know where they are, and we can get some information that way.

FLATOW: Well, there are all kinds of treaties for fishing all kinds of different things in the oceans. There's nothing for penguins yet?

BARHAM: Well, there are no local treaties. These treaties that exist are largely global scale. So whilst there are maximum allowable catches in certain areas, they normally do not give escapement in the local area under penguin colony. So penguin colonies can be on a small island, or it may just be a 40-mile area around that island that's important, whereas the fishing (unintelligible) vast tracts of the oceans.

FLATOW: Right. You said one of the real problems you have is collecting data from these penguins. How could you - what kind of technology could...

BARHAM: Well, technology is fairly getting better. But what we need at the moment - and this came up quite a lot in our discussions - is the things we can't found out about are in detail what the penguins are doing when they are fishing. We can put GPS loggers, the time-depth recorders, so we can see when they're diving, how deep they're diving. But we can't really tell when they're eating and what they're eating.

And then if we do that, typically, those devices will only last with the battery power we have for up to a few weeks. Or you can put them on - they switch on. So we don't know what happens through - most penguin species will spend about three or four months away feeding up between breeding seasons, and that is a crucial part. We don't know where they're doing it. So we can't say to the fishing industries please don't fish there at that time of year, because we don't know where to say.

FLATOW: And you don't have any money to study it, I'll bet?

BARHAM: The sort of money you're talking about for those sorts of things would be quite high, but, you know, a -I mean, a typical tracking device which you'd put on at that stage would be lost because the bird would molt and it would leave the device behind. So it has to be a satellite that dumps the information back to the satellites. Those things work out at around about 3 to $5,000 each. You would need to take maybe several hundred tracts to get any real data. So you're looking at several hundreds of thousands of dollars to get one season's worth of data. Not cheap.

FLATOW: That's not really a lot of money, either, in, you know, when you think - compared to other things.

BARHAM: Well, it's not a lot of money, but it's not the sort of money that gets given out for these sorts of conservation projects. They're not sexy. They don't attract high sums of money from funders, by and large.

FLATOW: Yeah. You need a TV show.

BARHAM: That's a good thought, yes. The TV shows tend to be on the nice, cuddly side of penguins. It doesn't mention, oh by the way, they're on the way down. The other thing you said, by the way, penguins being cute. I can assure you they are not cute. They are vicious things, generally speaking. They hurt. They bite and scratch and everything else. So, yeah.

FLATOW: Yeah. Years ago, I had a few Emperor Penguins friendly to me when I was in Antarctica, but...

BARHAM: Yeah, I mean, Emperor Penguins are so unaccustomed to people that they will generally wander up to you and ignore you. But if you were, however, to want to put a tracking device on one, you would need to constrain it. You would need to hold it, and then you'd probably feel how powerful its flippers are. Species I work with, the African Penguin, they have - a best description from a colleague of mine was: They're a pair of razorblades on legs.


FLATOW: Wow. Now I know why you've fallen in love with penguins. It's fascinating. Listen, when I was in Antarctica, I fell in love with them, too, down there. So I wish you good luck. I wish now you get the amount of money you need to do your research. Money's tight. It doesn't seem like a lot of money. Good luck to you.

BARHAM: OK. Thank you very much.

FLATOW: Peter Barham is a professional teaching fellow in physics at the University of Bristol and chair of the organizing committee for the Eighth International Penguin Conference, which took place this week in Bristol, U.K. Transcript provided by NPR.


Saturday, September 7, 2013

Novel Method to Identify Suitable New Homes for Animals Under Threat from Climate Change

Emperor penguins. (Credit: Copyright Dr. Paul Ponganis, National Science Foundation)

Sep. 5, 2013 — Scientists at the Zoological Society of London (ZSL) have devised a novel method to identify suitable new homes for animals under threat from climate change.

Conservation scientists used their knowledge on species ecology to create habitat suitability maps and correctly identify sites that will remain viable in the future regardless of changing climate. However, the key for success is to understand, and account for, the link between variation in species population size, climate and how the climate may change.

Almost half of all bird and amphibian species are believed to be highly vulnerable to extinction from climate change. Species in extreme or rare habitats such as the emperor penguin in the Antarctic and American pika in the USA have already experienced drastic declines in populations due to the impact of climate change on their home.

As climate changes, many species will need to move to a different location in order to survive. For species that aren't able to do this naturally, the only chance of survival is a helping hand through the use of translocations.

The research is published today (6 September) in the Journal of Applied Ecology.

Dr Nathalie Pettorelli, ZSL's climate change coordinator and senior author on the paper, says: "Climate change poses a worrying threat to many animals, and relocating vulnerable species to new and more suitable habitats may be the only way to protect them. However, this is an extreme conservation action, which needs to be thoroughly justified, and requires clear guidance on where threatened populations should be moved. Our research shows how these key requirements can be met."

The team used the hihi bird as an example because of the conservation success which came after efforts put into its relocation since the 1980s. Yet, despite large investments into its protection, climate change is now posing a significant threat to its future survival.

Dr Alienor Chauvenet, lead author of the study, says: "All current hihi populations are surrounded by either a large stretch of water or unsuitable habitat such as farmland or cities with plenty of non-native predators. This isolation makes it very perilous for them to move and individuals attempting to relocate naturally are unlikely to survive.

"Our work shows that assisted colonisation may be the only way to guarantee the survival of this unique species under climate change," Dr Chauvenet added.

Translocations will continue to be an important part of conservation as climate changes. ZSL's novel method shows how these interventions can be planned to be successful even under the influence of a changing environment. The method can be applied to any species threatened by climate change, and is likely to contribute to the success of future translocations.

Story Source:
The above story is based on materials provided by Zoological Society of London, via EurekAlert!, a service of AAAS.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Zoological Society of London (2013, September 5). Novel method to identify suitable new homes for animals under threat from climate change. ScienceDaily. Retrieved September 7, 2013, from http://www.sciencedaily.com­ /releases/2013/09/130905203018.htm

Tuesday, September 3, 2013

How Emperor Penguins stay underwater for 27 minutes

New research has revealed how the Emperor Penguin is able to dive to depths of over 500m and stay under water for up to 27 minutes – deeper and longer than any of its fellow avian species.
Researchers from the University of California will be presenting their new findings at the International Penguin Conference (IPC) which begins in Bristol today [02 September].

It's the first time the conference has been held in Europe, with 200 delegates from 30 countries sharing their latest research and knowledge at the University of Bristol and Bristol Zoo Gardens between 2 and 6 September.

Alexandra Wright and Dr Paul Ponganis investigated the heart rate response of Emperor Penguins as they made foraging trips to sea from the Cape Washington Colony in Antarctica.

Emperor Penguins also have unusually structured hemoglobin to allow it to function at low oxygen levels, solid bones to reduce barotrauma - physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with the body, and the surrounding fluid, and the ability to reduce metabolism and to shut down non-essential organ functions.

The profound decline in heart rate - known as bradycardia – decreases oxygen consumption, conserves the respiratory and blood oxygen stores, and isolates muscle, which must rely instead on its own oxygen store which is bound to the muscle protein, myoglobin.

Although this heart rate response contrasts with other birds and terrestrial mammals, it is similar to the dive response of marine mammals.

Archbishop Desmond Tutu recorded a special video message to launch the event, which will see delegates sample papers on everything from “monitoring global penguin population change” to “the power of poo.”

The public are also invited to get involved thanks to two public events this week. Bristol University graduate Elizabeth White, one of the directors of the popular Frozen Planet series, will be part of a free panel discussion entitled ‘Penguins on Film’ being held in the Wills Memorial Building on Wednesday, 4 September.

Footage from the BBC Natural History Unit, captured by a crew who spent four months with a penguin colony in the Antarctica, will show how Adelie penguins steal stones from its neighbours’ nests to elevate and protect their eggs from run-off when the Antarctic ice melts.

Captivating slow motion footage will illustrate that penguins can ‘fly’, showing how Emperor penguins – the largest of all penguins, reaching up to 120cm tall – manage to get airborne by swimming at speed towards the surface of the water and landing back on the ice.
  • For further details about the ‘Penguins on Film’ event, please see here. It’s free but booking is required.
There will also be an opportunity to learn more about the African penguin at Bristol Zoo Gardens on Saturday, 7 September, with activities for all the family and the chance to meet scientists and conservationists who work with African penguins in South Africa and Namibia.


Friday, August 23, 2013

Food Source for Penguins at Risk: Warming Antarctic Seas Likely to Impact On Krill Habitats

Aug. 22, 2013 — Antarctic krill are usually less than 6 cm in length but their size belies the major role they play in sustaining much of the life in the Southern Ocean. They are the primary food source for many species of whales, seals, penguins and fish.

Krill are known to be sensitive to sea temperature, especially in the areas where they grow as adults. This has prompted scientists to try to understand how they might respond to the effects of further climate change.

Using statistical models, a team of researchers from the British Antarctic Survey and Plymouth Marine Laboratory assessed the likely impact of projected temperature increases on the Weddell Sea, Scotia Sea and Southern Drake Passage, which is known for its abundance of krill. This region has experienced sea surface warming of as much as 1°C over fifty years. Projections suggest this could rise by another 1°C by the end of the 21st century.

The models are based on equations which link krill growth, sea surface temperature, and food availability. An analysis of the results, published this week in the online journal PLOS ONE, suggests warming, if continued, could reduce the area of growth habitat by up to 20%.

In the early life stages krill require deep water with low acidity and a narrow range of temperatures for their eggs to successfully hatch and develop. The larvae then feed on algae on the underside of sea ice.

The adults require suitable temperatures and enough of the right type of food (larger phytoplankton) to successfully grow and reproduce. Many of these critical environmental features (temperature, acidity, sea ice and food availability) could be affected by climate change.

The projected effects of warming are not evenly spread. The island of South Georgia is located within the area likely to be worst affected. Here the reduction in krill habitat could be as much as 55%. The island is home to a range of animals such as fur seals and macaroni penguins that depend upon krill, and others, such as black-browed albatrosses, which eat substantial amounts of krill as well as fish and squid. The researchers say animals which don't travel far to forage, such as fur seals, would be most affected by the projected changes.

Krill is also being commercially fished, although there is nothing to suggest current levels are unsustainable. In fact, at less than 1% of estimated biomass, catches are much lower than most other commercial fisheries.

But the Antarctic krill fishery took 68% of its total catch between 1980 and 2011 from the area of projected habitat degradation. The scientists suggest improved management systems to ensure the fisheries take into account both growing demand for catches and climate change.

Lead author, Dr. Simeon Hill, a marine biologist at BAS, said: "Each year, growth of Antarctic krill in the Southern Ocean produces new material that weighs twice as much as all the sugar produced in the world. Krill grow fastest in cold water and any warming can slow down or stop growth, reducing the food available for wildlife. Our research suggests that expected warming this century could severely reduce the area in which krill can successfully grow."

Although there is evidence that warming seas pose a threat to Antarctic krill habitats the team of researchers believe this can be mitigated with effective fisheries management systems in place.

Story Source:
The above story is based on materials provided by British Antarctic Survey.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. Simeon L. Hill, Tony Phillips, Angus Atkinson. Potential Climate Change Effects on the Habitat of Antarctic Krill in the Weddell Quadrant of the Southern Ocean. PLoS ONE, 2013; 8 (8): e72246 DOI: 10.1371/journal.pone.0072246

British Antarctic Survey (2013, August 22). Food source for whales, seals and penguins at risk: Warming Antarctic seas likely to impact on krill habitats. ScienceDaily. Retrieved August 23, 2013, from http://www.sciencedaily.com­ /releases/2013/08/130822091032.htm
Also, a more elaborate report is posted on the National Geographic website: HERE 

Thursday, August 22, 2013

Penguins Thrived in Antarctica During Little Ice Age

Here a colony of penguins on the Fildes Peninsula, which is located off the coast of Antarctica on King George Island, the largest of the South Shetland Islands.
Here a colony of penguins on the Fildes Peninsula, which is located off the coast of Antarctica on King George Island, the largest of the South Shetland Islands.
Credit: Zhouqing Xie
Penguin populations in the Ross Sea of Antarctica spiked during the short cold period called the Little Ice Age, which occurred between A.D.1500 and 1800, new research shows.

The results run contrary to previous studies that found increases in Antarctic penguin populations during warmer climates and decreases during colder climates, suggesting penguin populations living at different latitudes in the Antarctic may respond to climate change differently, scientists said.

"How ecological systems adapt to climate change is a very important and hot topic," said study researchers Liguang Sun and Zhouqing Xie, who are both environmental scientists at the University of Science and Technology of China in Hefei, China. "Our study suggests that it is not simple to answer this question," they told LiveScience in an email.

Determining penguin populations

The researchers and their colleagues have been studying the historical changes in penguin populations in the maritime Antarctic for more than a decade. Previous work had suggested the birds actually thrive when the climate is relatively warm, because cold climates increase sea-ice extent, which makes it difficult for penguins to access their beach colonies and waters that are rich in food (krill).

For the new study, the researchers decided to take a look at how the populations of Adélie penguins (Pygoscelis adeliae) changed over the past 700 years in the Ross Sea
, a region in Antarctica that is at a higher latitude than previous study sites. They analyzed sediment samples from multiple depths for cholesterol and cholestanol, which are biomarkers indicating soil contamination by animal feces (either from seals or penguins in Antarctica). They also analyzed the samples for two organic compounds related to algae and lichens, respectively.

Based on the variation in the markers, the team divided up the timeline into four periods. Seals dominated the study site during Period I, which occurred between A.D. 1280 and 1490 — the researchers determined the biomarkers came from seals rather than penguins because of the presence of seal hairs in the layers of sediment. After A.D. 1490, seal hairs disappeared from the samples, suggesting the animals left the area and never returned, though the researchers aren't sure why.

According to the biomarkers, penguin populations boomed during Period II (1490 to 1670), declined significantly during Period III (1670 to1950) and increased steadily since then in Period IV (1950 to present).

The amounts of vegetation corroborated the penguin data. Antarctic algae require a lot of nutrients from penguin droppings to thrive, whereas penguin trampling endangers lichens: The evidence shows that algae abundances increased and decreased along with the penguin populations, but lichen abundances showed the opposite trend.

On the rise

The researchers note a number of factors affect penguin populations, including temperatures, sea-ice extent, food, wind and snow cover. The summer temperatures during the Little Ice Age were about 2 degrees C (3.6 degrees F) colder than the previous 200 years — this chilly climate promoted more sea-ice extent, which would normally be detrimental to penguins.

However, ice core samples suggest that strong winds broke up the sea ice during Period II, allowing the birds to access their beach colonies. These winds also likely affected snow precipitation, resulting in low snow accumulation that allowed the penguins to build their nests.

Additionally, the penguins could dive into the pockets in the sea ice to eat krill, which were likely abundant because of all the algae growing under the sea ice (krill feed on algae).

Adélie penguin populationsare on the rise again now, because the climate is getting warmer and the Antarctic is experiencing a reduction in sea-ice extent, the researchers said.

The team is currently trying to track the long-term changes in krill populations by measuring nitrogen isotopes, or atoms of nitrogen with a different number of neutrons, in the feathers and bones of penguin remains. They are also interested in seeing if there are any differences in how other penguin species, including Emperor penguins 
 (Aptenodytes forsteri) and Gentoo penguins (Pygoscelis papua), respond to climate change.

"There are many unanswered and interesting questions, which we are expecting to further investigate," the researchers said.

The team detailed their work today (Aug. 22) in the journal (and you can download the paper here) Scientific Reports.