Wednesday, April 16, 2014

Gut capacity limits bird's ability to adapt to rapid climate change

Date:
April 15, 2014
Source:
University of Rhode Island
Summary:
An ornithologist has found that the capacity of a bird’s gut to change with environmental conditions is a primary limiting factor in their ability to adapt to the rapidly changing climate. And he believes that most other animals are also limited in a similar way.

Sparrow. An ornithologist who studies the physiological changes that birds undergo to migrate has found that the capacity of a bird's gut to change with environmental conditions is a primary limiting factor in their ability to adapt to the rapidly changing climate. And he believes that most other animals are also limited in a similar way. Credit: © chas53 / Fotolia
                                                                         ~~~~~

An ornithologist at the University of Rhode Island who studies the physiological changes that birds undergo to migrate has found that the capacity of a bird's gut to change with environmental conditions is a primary limiting factor in their ability to adapt to the rapidly changing climate. And he believes that most other animals are also limited in a similar way.
Scott McWilliams, URI professor of natural resources science, says that spare capacity -- the extent to which animals can modify their physiology to deal with ecological changes -- varies from species to species, with some having great capacity to change while others do not. "It's all about the time scale over which evolution occurs in relation to the timing of the changes now occurring in the environment, because there are likely to be mismatches," he said. "Our rapid climate change is happening too quickly for most animals to evolve a response." His research, funded by the National Science Foundation, was published last week in The Proceedings of the Royal Society.

McWilliams and a colleague at the University of Wisconsin measured the spare capacity of white-throated sparrows, a common migratory songbird in eastern North America. He found that birds acclimated to a very cold environment (-29C) were able to eat 2 to 4 times as much food as sparrows acclimated to summer temperatures, although the sparrows could not eat enough to live at temperatures colder than -29C. "They dramatically increase the size of their gut to accommodate the greater amount of food they must eat to meet their energy needs in the cold, yet they are able to just as efficiently digest their food when they eat much more," said McWilliams. "That tells us something about their ability to flexibly respond to climate change. Plenty of birds migrate south because they have too limited a capacity to respond in this way. But white-throated sparrows have the spare capacity to modify their physiology to deal with substantial environmental change."

However, when the birds were given no time to acclimate to the cold temperatures, they were only able to increase their food intake by about 50 percent. The researchers found that the birds needed at least two days to acclimate to the new conditions before they were able to eat more.

One implication of this finding is that birds that fly long distances in migration -- an activity that causes their gut size to decrease because they do not eat while flying -- need a day or two to reconstitute their gut before they can resume the maximum food intake required to continue their migration.

McWilliams says that his study has defined the ultimate limits of the gut capacity of white-throated sparrows. If similar limits could be established for other species, that data could be incorporated into climate models to better understand which species will likely be able to survive the coming environmental changes. "All organisms have some level of spare capacity," McWilliams said. "The animals that live in constant environments haven't had to evolve much capacity, so those animals are probably going to have the greatest challenge adapting to changing conditions."

According to the researchers, the limits of spare capacity have been studied in very few other species, with most work focused on several varieties of snakes. But they say that the limitations all animals face are in their ability to convert food into usable energy. "The gut limits the overall design of the animal," McWilliams said.

The URI researcher's next step is to do similar studies of how the fat composition of birds changes with environmental conditions and in response to their energy needs. Since certain polyunsaturated fats are known to improve flight performance, McWilliams said that this study will have relevance to the type of food birds should strive to eat in preparation for migration and thus what type of foods should be provided to birds in the landscape.

Story Source:
The above story is based on materials provided by University of Rhode Island. Note: Materials may be edited for content and length.

Journal Reference:
  1. S. R. McWilliams, W. H. Karasov. Spare capacity and phenotypic flexibility in the digestive system of a migratory bird: defining the limits of animal design. Proceedings of the Royal Society B: Biological Sciences, 2014; 281 (1783): 20140308 DOI: 10.1098/rspb.2014.0308


University of Rhode Island. "Gut capacity limits bird's ability to adapt to rapid climate change." ScienceDaily. ScienceDaily, 15 April 2014. <www.sciencedaily.com/releases/2014/04/140415133819.htm>.

Tuesday, March 25, 2014

Missing hormone in birds

Leptin found in mallard duck, peregrine falcon and zebra finch

Date:
March 24, 2014
Source:
University of Akron
Summary:
How does the Arctic tern (a sea bird) fly more than 80,000 miles in its roundtrip North Pole-to-South Pole migration? How does the Emperor penguin incubate eggs for months during the Antarctic winter without eating? These physiological gymnastics would usually be influenced by leptin, the hormone that regulates body fat storage, metabolism and appetite. However, leptin has gone missing in birds -- until now.

Male mallard duck. University of Akron researchers discovered leptin in the mallard duck, peregrine falcon and zebra finch, marking the first time the hormone has been found in birds.
Credit: Image courtesy of University of Akron


How does the Arctic tern (a sea bird) fly more than 80,000 miles in its roundtrip North Pole-to-South Pole migration? How does the Emperor penguin incubate eggs for months during the Antarctic winter without eating? How does the Rufous hummingbird, which weighs less than a nickel, migrate from British Columbia to Mexico? These physiological gymnastics would usually be influenced by leptin, the hormone that regulates body fat storage, metabolism and appetite. However, leptin has gone missing in birds -- until now.

of Akron researchers have discovered leptin in birds, In their "Discovery of the Elusive Leptin in Birds: Identification of Several 'Missing Links' in the Evolution of Leptin and its Receptor," published March 24, 2014, in the journal PLOS ONE, UA researchers reveal their findings of leptin in the peregrine falcon, mallard duck and zebra finch.

UA Professor of Biology R. Joel Duff made the initial discovery by comparing ancient fish and reptile leptins to predict the bird sequence. Duff, along with undergraduate students Cameron Schmidt and Donald Gasper, identified the sequence in multiple bird genomes and found that the genomic region where leptin was found is similar to that of other vertebrates. Jeremy Prokop, a former UA Integrated Bioscience doctoral student who initiated the project, then constructed computer models of the bird leptin's three-dimensional structure and performed bench experiments to show that the bird leptin can bind to a bird leptin receptor. Richard Londraville, research team member and UA professor of biology, says that the search for leptin in birds has been a bit of a race among scientists.

Crucial discovery "It has been a pretty big deal because people wanted to study leptin in birds for the poultry industry, for instance, to develop faster growing and tastier chicken," Londraville says, noting that, interestingly, leptin has yet to be discovered in chickens, perhaps because their gene structure varies from that of other birds.

Robert Dores, editor-in-chief of the journal General and Comparative Endocrinology, says the discovery represents a significant turning point in leptin study. "This study now sets the stage for future studies on the evolution of leptin function ... and reinforces that studies on hormone sequences should be complemented by hormone receptor modeling studies," says Dores, a University of Denver professor of biological sciences. "The world of comparative endocrinology has entered the 21st century."
 

Story Source:
The above story is based on materials provided by University of Akron. Note: Materials may be edited for content and length.

Journal Reference:
  1. Jeremy W. Prokop, Cameron Schmidt, Donald Gasper, Robert J. Duff, Amy Milsted, Takeshi Ohkubo, Hope C. Ball, Matthew D. Shawkey, Herman L. Mays Jr, Larry A. Cogburn, Richard L. Londraville. Discovery of the Elusive Leptin in Birds: Identification of Several ‘Missing Links’ in the Evolution of Leptin and Its Receptor. PLoS ONE, March 2014; DOI: 10.1371/journal.pone.0092751


University of Akron. "Missing hormone in birds: Leptin found in mallard duck, peregrine falcon and zebra finch." ScienceDaily. ScienceDaily, 24 March 2014. <www.sciencedaily.com/releases/2014/03/140324184227.htm>.

Saturday, March 22, 2014

Global warming sees predator gulls thrive and pose threat to penguins

Late summers spark rise in predator gull numbers in Chile bird paradise

penguinsonice.jpgPUBLISHED : Friday, 21 March, 2014

Global warming could threaten the long-term survival of penguins. Photo: Xinhua

Magdalena Island, near Chile's southern tip, is a natural paradise for tens of thousands of penguins that come every year to breeYet global warming could threaten the long-term survival of the species, say experts at the island nature reserve in the Strait of Magellan, about 50 kilometres from the city of Punta Arenas.

The island is home to 22 bird species - 11 that nest all the year round and 11 seasonal visitors - including Magellanic penguins.

About 23,000 tourists a year make the pilgrimage to Los Pinguinos Natural Monument, a protected area comprising tiny Marta Island and windswept Magdalena Island.

The penguins' main predators were aggressive seabirds called skuas and Dominican gulls, which feed on penguin eggs and young, says Roberto Fernandez, a ranger at the site.

Right now, the population of these predators was growing. "We are seeing summer starting late, then lasting through into March; climate change is bringing about a rise in gull numbers," says monument administrator Neftali Aroca.

"You would have to undertake a long-term study in order to link this increase with a reduction in the penguin population, but the forecast is that in the future, the penguins could be at risk."

The worrying prognosis seems to confirm fears raised in January in a study published in the scientific journal PLOS ONE, which indicated that extreme weather conditions, such as unseasonable warmth and heavy rainfall, may have killed off a considerable number of young Magellanic penguins.

The study - conducted over 27 years in Argentina's Punta Tombo peninsula, the largest breeding ground for the species - showed that, on average, 65 per cent of the colony's young died annually, 40 per cent from hunger and 7 per cent because of the effects of climate change.

Each year, the penguins flee the cold to spend winter in the warmer waters off Brazil. As soon as they are big enough to swim, they head off on a 4,000-kilometre journey from Magdalena Island to Brazil.

They spend the Southern Hemisphere winter on the coast of Brazil's southern Santa Catarina state - though they sometimes make it as far up as Rio de Janeiro's beaches.

From mid-August, they begin to head back, via Uruguay and Argentina to the Strait of Magellan, the natural passage between the Atlantic and Pacific oceans, and Magdalena Island.

"Magellanic penguins come to the island to complete their reproductive cycle," says Valeria Sanchez, who has spent five years as a tour guide here."

They start arriving in September, as summer approaches, to enjoy the longer days necessary to incubate their eggs and look after their young."
Magellanic penguins, which can live up to 25 years, are monogamous and share their lives with only one partner.

First to arrive on Magdalena Island are the males, who must seek out the burrowed nests dug the previous season and make any necessary changes with whatever material they can find, including stones and feathers, before attracting their mate.

About a fortnight later, the females arrive, and their keen partners sound a trumpet-like call to guide them to the nest.

After fertilisation, the female penguin lays one or two eggs; for the first 12days, she will incubate them and not leave them - even to eat.

Following their long fast, the mothers give way to the males so they can feed. The couples switch at roughly fortnightly intervals until the end of the 40-to-45-day incubation period ahead of hatching in around November.

"Between February and March, they start to leave the island, but this year they began leaving two or three weeks earlier," Sanchez says. This article appeared in the South China Morning Post print edition as Global warming threatens penguins

source 

Saturday, March 15, 2014

Can penguins cope with climate change? Scientists find different types of ice elicit different responses

mongabay.com
March 13, 2014

Pygoscelis adeliae). In an article recently published in PLOS ONE, a team of researchers led by Amélie Lescroël from the Centre d'Ecologie Fonctionnelle et Evolutive (CNRS) in France, found that changes in sea-ice content and newly formed icebergs significantly impacted Adélie penguin communities in the Ross Sea.

Climate change is leading to major shifts in sea ice. One of the largest glaciers in Antarctica has begun to melt at a rate some scientists describe as irreversible. Pine Island Glacier contributes a fourth of the discharge of the West Antarctic Ice Sheet. It is estimated that if this entire ice sheet were to melt, sea levels would rise by ten feet. Other areas of the Antarctic are experiencing cooling events, resulting in greater ice coverage known as "fast ice." However, scientists believe that melting will supplant fast ice in the near future.

“An

An Adélie Penguin (Pygoscelis adeliae). Photo courtesy of Reinhard Jahn under a Creative Commons Attribution-Share Alike 2.0 Germany license.

"While net sea ice cover (i.e., the area of ocean covered by ice) has increased over the past few decades [in Antarctica] owing to wind changes brought largely by mid-latitude warming and the Antarctic Ozone Hole, modeled predictions point to a decrease by 5-15 percent, depending on sector, by 2025-2052," the study states. "Concomitantly, increased ice shelf instability will lead to more frequent iceberg calving, including very large icebergs (hundreds of square kilometers)."

Sea ice cover variability directly affects Adélie habitat, and the species' ability to adjust to this variability will determine their future.

Adélie penguins depend on sea-ice for foraging, resting, molting, breeding and migrating. They are one of only two penguin species that depend on sea ice and not icebergs, the other being the Emperor penguin (Aptenodytes forsteri).

"This 'dependence' is actually a manifestation of them being the only penguin species that are able to cope with sea ice," Lescroël told mongabay.com.

To a certain extent, Adélie penguins are adapted to cope with changes in their habitat. For instance, they're able to easily gain and lose fat depending on ice conditions, and dive for longer periods of time compared to other penguin species.

"They dive mostly between 10 and 50 meters deep to catch their prey but can dive up to 180 meters, which is a world record," said Lescroël.

The southernmost extent of Adélie habitat is the Ross Sea, where 38 percent of the world's population resides. Lescroël and her colleagues evaluated data that had been collected over thirteen years at Cape Crozier on Ross Island, a volcanic island located near the Antarctic mainland.

The researchers conducted their study in a fenced-in nesting area installed in 1996, allowing penguins access through only one entrance outfitted with a scale. They collected each penguin's trip duration as well as changes in weight within breeding seasons and over multiple years. Using these data, the researchers were able to record how long it took the penguins to forage and how much food they brought back to their chicks.

"When they are nesting, parents take turns on the eggs or chicks," Lescroël said. "One of the parents stays at the nest while the other goes [to] sea to catch food. On Ross Island, Adélie penguins feed on crystal krill and silverfish. They swallow the prey as they catch it, underwater. When they come back to the nest, they regurgitate the food to their chicks."

Since Adélie penguins depend on sea-ice, one might expect the increased presence of "fast ice" in some areas would equate to habitat expansion. However, the study's findings indicate this is not necessarily so. When there was less sea-ice, the penguins were able to fish for longer periods of time and bring more food back to their chicks.

"This is mainly because when there is lots of concentrated sea ice, penguins have to walk over the sea ice (rather than swim) to reach the open water where they could dive," Lescroël said. "This is more costly in time and energy. But this is when environmental conditions are "normal."

In the middle of the study, when four giant icebergs broke off as a result of increased melting the research team labeled this as an extreme environmental event. The icebergs were present in Cape Crozier's landscape for 5 years, and the unique event allowed the team to observe how Adélie penguins responded to icebergs.

"The presence of these icebergs dramatically changed the physical environment of the penguins in many ways: less open water was available for diving; penguins were disoriented due to the movements of these huge blocks of ice just in front of the colony; there was less ocean productivity in the first year; and there were changes in the drift pattern of pack ice," Lescroël said, adding that "the changes were so extreme that sea ice concentration did not matter anymore. The foraging efficiency of Adélie penguins was constrained to lower levels during these five years, no matter what the sea ice concentration was."

While the icebergs were present, fewer chicks were reared than usual although the number of adults was not affected. However, soon after the icebergs left the area, breeding levels returned to normal.

"Our work shows that if the frequency of such extreme events increases, then it will become very hard to predict how penguin populations will buffer future sea ice changes," Lescroël said.

Map of the study area provided in the PLoS ONE article. The colony location is indicated by the star, the foraging area of Adelie penguins (in red) and where the giant icebergs were located. Satellite images are from http://lance-modis.osdis.nasa.gov. A: Illustrates a typical iceberg year (Dec. 21, 2004). B: Illustrates a typical non-iceberg year (Dec. 21, 2008).
Map of the study area provided in the PLoS ONE article. The colony location is indicated by the star, the foraging area of Adelie penguins (in red) and where the giant icebergs were located. Satellite images are from http://lance-modis.osdis.nasa.gov. A: Illustrates a typical iceberg year (Dec. 21, 2004). B: Illustrates a typical non-iceberg year (Dec. 21, 2008).

Citations: Lescroël A, Ballard G, Grémillet D, Authier M, Ainley DG (2014) Antarctic Climate Change: Extreme Events Disrupt Plastic Phenotypic Response in Adélie Penguins. PLoS ONE 9(1): e85291. doi:10.1371/journal.pone.0085291

source 

Friday, February 28, 2014

Big thaw projected for Antarctic sea ice: Ross Sea will reverse current trend, be largely ice free in summer by 2100


Emperor Penguins: Changes in the extent and duration of Ross Sea ice will significantly impact marine life in what is one of the world’s most productive and unspoiled marine ecosystems, where rich blooms of phytoplankton feed krill, fish, and higher predators such as penguins.
Credit: Photo courtesy of Walker Smith

Date:
February 27, 2014
Source:
Virginia Institute of Marine Science
Summary:  A new modeling study suggests that a recent observed increase in summer sea-ice cover in Antarctica's Ross Sea is likely short-lived, with the area projected to lose more than half its summer sea ice by 2050 and more than three quarters by 2100. These changes will significantly impact marine life in what is one of the world's most productive and unspoiled marine ecosystems.

Antarctica's Ross Sea is one of the few polar regions where summer sea-ice coverage has increased during the last few decades, bucking a global trend of drastic declines in summer sea ice across the Arctic Ocean and in two adjacent embayments of the Southern Ocean around Antarctica.
 
Now, a modeling study led by Professor Walker Smith of the Virginia Institute of Marine Science suggests that the Ross Sea's recent observed increase in summer sea-ice cover is likely short-lived, with the area projected to lose more than half its summer sea ice by 2050 and more than three quarters by 2100.

These changes, says Smith, will significantly impact marine life in what is one of the world's most productive and unspoiled marine ecosystems, where rich blooms of phytoplankton feed krill, fish, and higher predators such as whales, penguins, and seals.

Smith, who has been conducting ship-based fieldwork in the Ross Sea since the 1980s, collaborated on the study with colleagues at Old Dominion University. Their paper, "The effects of changing winds and temperatures on the oceanography of the Ross Sea in the 21st century," appears in the Feb. 26 issue of Geophysical Research Letters. Smith's co-authors are Mike Dinniman, Eileen Hofmann, and John Klinck.

Smith says "The Ross Sea is critically important in regulating the production of Antarctica's sea ice overall and is biologically very productive, which makes changes in its physical environment of global concern. Our study predicts that it will soon reverse its present trend and experience major drops in ice cover in summer, which, along with decreased mixing of the vertical column, will extend the season of phytoplankton growth. These changes will substantially alter the area's pristine food web."

Researchers attribute the observed increase in summertime sea ice in the Ross Sea -- where the number of days with ice cover has grown by more two months over the past three decades -- to a complex interplay of factors, including changes in wind speed, precipitation, salinity, ocean currents, and air and water temperature.

But global climate models agree that air temperatures in Antarctica will increase substantially in the coming decades, with corresponding changes in the speed and direction of winds and ocean currents. When Smith and his colleagues fed these global projections into a high-resolution computer model of air-sea-ice dynamics in the Ross Sea, they saw a drastic reduction in the extent and duration of summer sea ice.

The modeled summer sea ice concentrations decreased by 56% by 2050 and 78% by 2100. The ice-free season also grew much longer, with the mean day of retreat in 2100 occurring 11 days earlier and the advance occurring 16 days later than now.

Also changed was the duration and depth of the "shallow mixed layer," the zone where most phytoplankton live. "Our model projects that the shallow mixed layer will persist for about a week longer in 2050, and almost three weeks longer in 2100 than now," says Smith. "The depth of the shallow mixed layer will also decrease significantly, with its bottom 12% shallower in 2050, and 44% shallower in 2100 than now."

For Smith, these changes in ice, atmosphere, and ocean dynamics portend major changes in the Antarctic food web. On the bright side, the decrease in ice cover will bring more light to surface waters, while a more persistent and shallower mixed layer will concentrate phytoplankton and nutrients in this sunlit zone. These changes will combine to encourage phytoplankton growth, particularly for single-celled organisms called diatoms, with ripples of added energy potentially moving up the food web.

But, Smith warns, the drop in ice cover will negatively affect several other important species that are ice-dependent, including crystal krill and Antarctic silverfish. A decrease in krill would be particularly troublesome, as these are the major food source for the Ross Sea's top predators -- minke whales, Adélie and Emperor penguins, and crabeater seals.

Overall, says Smith, "our results suggest that phytoplankton production will increase and become more diatomaceous. Other components of the Ross Sea food web will likely be severely disrupted, creating significant but unpredictable impacts on the ocean's most pristine ecosystem."

Story Source:
The above story is based on materials provided by Virginia Institute of Marine Science. The original article was written by David Malmquist. Note: Materials may be edited for content and length.

Journal Reference:
  1. Walker O. Smith, Michael S. Dinniman, Eileen E. Hofmann, John M. Klinck. The effects of changing winds and temperatures on the oceanography of the Ross Sea in the 21stcentury. Geophysical Research Letters, 2014; DOI: 10.1002/2014GL059311


Virginia Institute of Marine Science. "Big thaw projected for Antarctic sea ice: Ross Sea will reverse current trend, be largely ice free in summer by 2100." ScienceDaily. ScienceDaily, 27 February 2014. <www.sciencedaily.com/releases/2014/02/140227115512.htm>.

Thursday, February 27, 2014

Waterbirds' hunt aided by specialized tail: Swimming birds evolved rudder-like tail to dive for food

Date:
February 26, 2014
Source:
PLOS
Summary:
The convergent evolution of tail shapes in diving birds may be driven by foraging style. Birds use their wings and specialized tail to maneuver through the air while flying. It turns out that the purpose of a bird's tail may have also aided in their diversification by allowing them to use a greater variety of foraging strategies. To better understand the relationship between bird tail shape and foraging strategy, researchers examined the tail skeletal structure of over 50 species of waterbirds, like storks, pelicans, and penguins, and shorebirds, like gulls and puffins. They first categorized each species by foraging strategy, such as aerial, terrestrial, and pursuit diving, and then compared the shape and structure of different tails.


This is a contrast of the typical elongate pygostyle of a diving bird (A), the Adélie Penguin (Pygoscelis adeliae, specimen AMNH 623439) to the typical short, dorsally deflected pygostyle of a non-diving bird (B), the Northern Fulmar (Fulmarus glacialis, specimen AMNH 20697).
Credit: Ryan Felice; CC-BY


The convergent evolution of tail shapes in diving birds may be driven by foraging style, according to a paper published in PLOS ONE on February 26, 2014 by Ryan Felice and Patrick O'Connor from Ohio University.
Birds use their wings and specialized tail to maneuver through the air while flying. It turns out that the purpose of a bird's tail may have also aided in their diversification by allowing them to use a greater variety of foraging strategies. To better understand the relationship between bird tail shape and foraging strategy, researchers examined the tail skeletal structure of over 50 species of waterbirds, like storks, pelicans, and penguins, and shorebirds, like gulls and puffins. They first categorized each species by foraging strategy, such as aerial, terrestrial, and pursuit diving, and then compared the shape and structure of different tails.


Scientists found that foraging style groups differed significantly in tail skeletal shape, and that shape could accurately "predict" foraging style with only a small amount of mismatch. In particular, underwater foraging birds, such as cormorants, penguins, puffins, gannets, and tropicbirds, have separately evolved a similarly specialized elongated tail structure, whereas aerial and terrestrial birds have a short, dorsally deflected tail structure. Moreover, each underwater foraging group, such as foot propelled, wing propelled, or plunge diving, had a distinctive tail-supporting vertebrae shape. 
According to the authors, the probable separate evolution of the specialized tail in underwater-diving birds may suggest that body structure adapted to the demand, or the need to move the tail as a rudder during underwater foraging. In contrast, the authors found no conclusive results when looking at the relationship between tail shape and flight style.

Mr. Felice adds, "Previous research has shown that diving birds evolve specializations in wing and leg morphology to facilitate underwater locomotion. This study puts a necessary focus on the tail, finding that this region of the body also evolves in response to the demands of underwater movement."

Story Source:
The above story is based on materials provided by PLOS. Note: Materials may be edited for content and length.

Journal Reference:
  1. Ryan N. Felice, Patrick M. O’Connor. Ecology and Caudal Skeletal Morphology in Birds: The Convergent Evolution of Pygostyle Shape in Underwater Foraging Taxa. PLoS ONE, 2014; 9 (2): e89737 DOI: 10.1371/journal.pone.0089737


PLOS. "Waterbirds' hunt aided by specialized tail: Swimming birds evolved rudder-like tail to dive for food." ScienceDaily. ScienceDaily, 26 February 2014. <www.sciencedaily.com/releases/2014/02/140226174546.htm>.

Tuesday, February 25, 2014

New insights into origin of birds focuses on key characteristics that preceded flight: Body size, forelimb length

Date:
February 23, 2014
Source:
University of Bristol
Summary:
The key characteristics of birds which allow them to fly -- their wings and their small size -- arose much earlier than previously thought, according to new research that examined closely the Paraves, the first birds, and their closest dinosaurian relatives which lived 160 to 120 million years ago. Researchers investigated the rates of evolution of the two key characteristics that preceded flight: body size and forelimb length. In order to fly, hulking meat-eating dinosaurs had to shrink in size and grow much longer arms to support their feathered wings.


Ruby Throated Hummingbird in flight. Being small and light is important for a flyer, and it now seems a whole group of dozens of little dinosaurs were lightweight and had wings of one sort or another. Most were gliders or parachutists, spreading their feathered wings, but not flapping them.
Credit: © gregg williams / Fotolia


The key characteristics of birds which allow them to fly -- their wings and their small size -- arose much earlier than previously thought, according to new research from the Universities of Bristol and Sheffield into the Paraves, the first birds and their closest dinosaurian relatives which lived 160 to 120 million years ago.
Mark Puttick and colleagues investigated the rates of evolution of the two key characteristics that preceded flight: body size and forelimb length. In order to fly, hulking meat-eating dinosaurs had to shrink in size and grow much longer arms to support their feathered wings. "We were really surprised to discover that the key size shifts happened at the same time, at the origin of Paraves," said Mr Puttick of Bristol's School of Earth Sciences. "This was at least 20 million years before the first bird, the famous Archaeopteryx, and it shows that flight in birds arose through several evolutionary steps."

Being small and light is important for a flyer, and it now seems a whole group of dozens of little dinosaurs were lightweight and had wings of one sort or another. Most were gliders or parachutists, spreading their feathered wings, but not flapping them. "Out of all these flappers and gliders, only the birds seem to have been capable of powered flight," said co-author Mike Benton, Professor of Vertebrate Palaeontology at Bristol. "But you wouldn't have picked out Archaeopteryx as the founder of a remarkable new group."

The study applied new numerical methods that calculate the rate of evolution of different characteristics across a whole evolutionary tree, and identify where bursts of fast evolution occurred. "Up to now you could only have guessed roughly where the major evolutionary transitions occurred," said Dr Gavin Thomas of the University of Sheffield, "but the new methods pinpoint the size changes. The small size of birds and their long wings originated long before birds themselves did."

Birds owe their success to their flight, wings and feathers. Until the 1990s, when the first feathered dinosaurs were found in China, birds were thought to have originated rapidly, marking a major transition from dinosaurs. Now, we know that Archaeopteryx was only one of a large number of small, flying dinosaurs. "The origin of birds used to be seen as a rapid transition," said Mark Puttick, "but now we know that the key characteristics we associate with them arose much earlier."

Story Source:
The above story is based on materials provided by University of Bristol. Note: Materials may be edited for content and length.

Journal Reference:
  1. Mark N. Puttick, Gavin H. Thomas, Michael J. Benton. HIGH RATES OF EVOLUTION PRECEDED THE ORIGIN OF BIRDS. Evolution, 2014; DOI: 10.1111/evo.12363


University of Bristol. "New insights into origin of birds focuses on key characteristics that preceded flight: Body size, forelimb length." ScienceDaily. ScienceDaily, 23 February 2014. <www.sciencedaily.com/releases/2014/02/140223215134.htm>.

Thursday, February 13, 2014

Yellow-eyed penguins forage in trawlers' wake


A yellow-eyed penguin. Photo / Thinkstock
A yellow-eyed penguin. Photo / Thinkstock
 
New Zealand's endangered yellow-eyed penguin have been found to follow the line of swooping seabirds - literally - when it comes to reaping the food stirred up by trawlers.

An Otago University research team have discovered the penguins, of which there were around 500 estimated pairs left on mainland New Zealand, forage in straight lines for several kilometres by following furrows in the seafloor scoured out by fishing trawlers.

Using GPS dive loggers the researchers monitored the penguins' movements over three years showing the birds use furrows scoured on the seabed by otter boards from trawl nets to find food, particularly blue cod. "This research is unique as it shows for the first time that not only do flying seabirds follow fishing vessels, but also penguins, with the latter foraging after a trawler has gone through a particular area," lead research Professor Philip Seddon said.

The researchers said blue cod and other bottom feeders were likely to forage around the seafloor lines because they were attracted to the marine life stirred up and exposed by the action of the nets being dragged behind fishing trawlers. The lines made by the otter boards, which keep the mouth of the trawl net open, are up to 15cms wide and two centimetres in depth on a north-east to south-west axis.

They can remain on the sea floor for a year or more and are clearly visible. GPS dive loggers were attached to the back of the birds to determine the depth the penguins dive, their locations and line of travel and how far they swim in one foraging trip. Lines on the seafloor were located by using video footage taken by a remote operated vehicle launched from the university's research vessel Polaris II.

Many penguins swim to a depth of between 60 and 70 metres to feed during multiple dives - up to 80 - over several hours before returning to shore. The penguins can travel up to 120 kilometres in one trip, while foraging in the mid-shelf fishing grounds some 20 kilometres off the Otago Peninsula.

The study shows that the birds also revisit the lines on subsequent occasions and might develop a visual memory of the area, researchers say. "It appears that using the lines for foraging is particularly related to bad breeding years when penguins are more likely to go further out to sea to find blue cod and other bottom feeders. This might also be due to the individual preference of some birds though," said Dr Thomas Mattern, the first author of the paper reporting the results. But the researchers say that one of the downsides of foraging around the trawl lines might be that an exclusive diet of blue cod, which tends to be low in nutritional value, could affect breeding.

As yet, there was no confirmation of this hypothesis and further research was needed to determine if there is any relationship between foraging patterns, diet quality and breeding success in the penguin population.

The research was published in the journal PloS ONE and supported by the Yellow-Eyed Penguin Trust.

source

Thursday, January 30, 2014

Rains Spurred by Climate Change Killing Penguin Chicks


Three chicks suffer from hypothermia and die after a rainstorm.
Credit: D. Boersma/U of Washington
Penguin-chick mortality rates have increased in recent years off the coast of Argentina — a trend scientists attribute to climate change and expect to worsen throughout the century, a new study finds.

From 1983 through 2010, researchers based at the University of Washington in Seattle monitored a colony of roughly 400,000 Magellanic penguins living halfway up the coast of Argentina on a peninsula called Punta Tombo. Each year, the researchers visited penguin nests once or twice a day from mid-September through late February to assess the overall status of the colony and the health of the chicks once they hatched in late November or early December. [Gallery of Magellanic Penguin Colony]

The resulting data set provides one of the longest-ever records of a single penguin colony. It revealed that starvation and predation were the most common and consistent chick killers over the years, but that hypothermia was the leading cause of death during years with heavy rainstorms, which became more prevalent throughout the study period — a trend that is consistent with climate models projecting the effects of climate change in the region.



This chick has found refuge in a burrow, where the water is still shallow enough to not wet its  
        downey plummage . Credit: D. Boersma/U of Washington


Young chicks between 9 and 23 days old were particularly vulnerable to hypothermia, as they were too young to have fully grown their waterproof plumage but already too big to seek shelter under their parents' bodies, the team reports today (Jan. 29) in the journal PLOS ONE. "They have to have waterproof feathers to survive," study co-author Dee Boersma told LiveScience. "If chicks don't have waterproof plumage, they are going to die as soon as they end up in the water."

Extreme heat — another component of climate change expected to worsen throughout the century — also challenged chicks' temperature-regulation systems and resulted in deaths, though not as many as hypothermia did, the team reports.

David Ainley, a senior wildlife ecologist at ecological consulting firm H.T. Harvey & Associates who studies Antarctic penguin colonies, says that, aside from giving Magellanic chicks the chills, rain can also damage the burrows that they live in during their early days. "I think that [penguin] pairs that have good burrows probably wouldn't suffer much of an effect, but it might be harder for pairs that have not competed successfully for where to make their burrow," Ainley, who was not involved in this study, told LiveScience. "Shallow burrows, or no burrow at all — those would be the ones that are most affected by rain."

Climate-change connection

The team noted that not all rainstorms killed the chicks. Of the 233 storms that occurred over the course of the study period, only 16 resulted in chick deaths. Still, the researchers pointed out that the types of heavy storms that did result in mortalities are projected to become more frequent, with some climate models predicting an increase in extreme precipitation in the Southern Hemisphere summer by 40 to 70 percent between 2076 and 2100, compared with that seen between 1951 and 1976.

Though the researchers only analyzed a single Magellanic colony in the study, they expect that colonies of the same species elsewhere along the coasts of Chile and Argentina likely react similarly to changes in weather patterns.

Wayne Trivelpiece, an Antarctic penguin researcher with the National Oceanographic and Atmospheric Administration's Southwest Fisheries Science Center, based in La Jolla, Calif., agrees that climate change is a serious threat to these and other penguin populations around the world. He has spent nearly the past 40 years studying penguins in Antarctica, and said he has also seen a decline in populations that he feels comfortable attributing to the indirect effects of climate change. "I don't think it is a real stretch to make that kind of connection," Trivelpiece told LiveScience. "But the actual hard evidence will come many decades down the road."

source

Wednesday, January 8, 2014

Hope for Antarctic Emperor Penguins Amidst Changing Climate (New Paper)

SustainableBusiness.com News
January 8, 2014
 
Among the great tragedies associated with climate change is that it is causing one of the greatest species extinctions of all time - a majority of plants and animals won't be able to adapt fast enough to the changing climate.

But there's some hope for Antarctic Emperor Penguins as a new study shows they may be adapting to environmental changes.
 
Satellite observations reveal that penguin colonies are actually moving away from traditional breeding grounds when there's not enough ice.

“These charismatic birds tend to breed on sea ice because it gives them relatively easy access to waters where they hunt for food.  Satellite observations captured of one colony in 2008, 2009 and 2010 show that the concentration of annual sea ice was dense enough to sustain a colony. But this was not the case in 2011 and 2012 when sea ice didn't form until a month after the breeding season began. During those years the birds moved up onto the neighbouring floating ice shelf to raise their young," says Peter Fretwell, lead author of the research and from the British Antarctic Survey.
 Penguin Emperor

“What’s particularly surprising is that climbing up the sides of a floating ice shelf – which at this site can be up to 30 metres high – is a very difficult manoeuvre for emperor penguins.  Whilst they are very agile swimmers they have often been thought of as clumsy out of the water,” he adds.

Reporting this week in the online journal, PLOS ONE, a team of scientists from British Antarctic Survey, the Australian Antarctic Division and the Scripps Institution of Oceanography at UC San Diego in California, describe this extraordinary change in behaviour.   
 
Because emperor penguins rely on sea ice as a breeding platform coupled with concerns about changing patterns of sea ice, the species is designated as ‘near threatened’ on the International Union for Conservation of Nature (IUCN) red list.

Scientific models suggest that levels of sea ice around Antarctica will decline over coming decades. Some forecasts predict Emperor Penguin numbers will halve before 2052 and more northerly colonies could be lost.
 
Barbara Wienecke from the Australian Antarctic Division says, “These new findings are an important step forward in helping us understand what the future may hold for these animals, however, we cannot assume that this behaviour is widespread in other penguin populations.  The ability of these four colonies to relocate to a different environment – from sea ice to ice shelf - in order to cope with local circumstances, was totally unexpected.  We have yet to discover whether or not other species may also be adapting to changing environmental conditions.” 


Whereas sea-ice is frozen salt water, ice shelves are made up of glacial ice that has flowed from the land into the sea.  Ice cliffs can form at the outer edge of an ice shelf and they can be up to 60 metres high. 

source 

You can download the Emperor Penguin study here:
Website: http://dx.plos.org/10.1371/journal.pone.0085285

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