2015/08/21

Worsening wind forecasts could signal stormy times ahead for seabirds


Worsening wind forecasts could signal stormy times ahead for seabirds

http://www.ceh.ac.uk/news-and-media/news/worsening-wind-forecasts-could-signal-stormy-times-ahead-seabirds


Stronger winds forecast as a result of climate change could impact on populations of seabirds, a new study suggests.
Research into a common UK coastal seabird, the European shag, showed that when winds are strong, females take much longer to find food compared with their male counterparts. Researchers expect that if wind conditions worsen - as they are forecast to do - this could impact on the wellbeing of female birds, and ultimately affect population sizes.
Scientists from the University of Edinburgh, the Centre for Ecology & Hydrology (CEH) and the British Antarctic Survey carried out a two-year study into the cormorant-like Shags on the Isle of May National Nature Reserve in south-east Scotland. Small tracking devices were attached to the legs of birds and measured how long they foraged for fish in the sea.
Researchers expect that if wind conditions worsen, as they are forecast to do, this could impact on the wellbeing of female birds and ultimately affect population sizes
In many seabird species, females are smaller and lighter than males, and so must work harder to dive through turbulent water. They may not hold their breath for as long, fly so efficiently nor dive as deeply as males. The latest results suggest that in poor weather conditions, this sex difference is exaggerated.
The scientists found that when coastal winds were strong or blowing towards the shore, females took much longer to find food compared with males. The difference in time spent foraging became more marked between the sexes when conditions worsened, suggesting that female birds are more likely to continue foraging even in the poorest conditions.
European shags around nest sites on the west cliffs of the Isle of May (photo: Mark Newell)
A brisk westerly wind creating rough conditions along the west cliffs of the Isle of May. European shags loiter around nest sites (Photo: Mark Newell).
The research was carried out as part of the long-term CEH seabird study on the Isle of May that began in the 1970s.
Lead author Dr Sue Lewis from the University of Edinburgh said, “In our study, females had to work harder than males to find food, and difficult conditions exacerbated this difference. Forecasted increases in wind speeds could have a greater impact on females, with potential knock-on effects on the wellbeing of populations.”
Co-author Dr Francis Daunt, of the Centre for Ecology & Hydrology, said, “Most of the research on climate change has focused on the effects of warming, but there is growing concern about increasing wind speeds and frequency of storms. This study shows one way in which wind could affect wild populations, and may be widespread since many species have sex differences in body size.”
The research was funded by the Natural Environment Research Council and published in the Journal of Animal Ecology.

Additional information

The full paper is open access at the Journal of Animal Ecology: Contrasting responses of male and female foraging effort to year-round wind conditions, doi: 10.1111/1365-2656.12419
The University of Edinburgh issued a press release for this story.
The study was carried out as part of CEH's long-term Isle of May monitoring project

2015/01/01

Errepideetara botatzen den gatza ere, hegaztien hiltzaile

http://www.ornithomedia.com/breves/salage-routes-cause-mortalite-sous-estimee-pour-certains-passereaux-01604.html

Le salage des routes, une cause de mortalité sous-estimée pour certains passereaux

Les Carduelinés sont particulièrement attirés par les granules de sel, ce qui peut causer leur perte

Le sel (chlorure de sodium) répandu sur les routes lors des épisodes de gel ou de neige a plusieurs effets négatifs sur l'environnement : il modifie localement la nature des sols, brûle le feuillage des végétaux et dessèche leurs racines, il irrite les pattes des animaux domestiques (chiens, chats) et il augmente la mortalité des chenilles se nourrissant des plantes ayant poussé en bordure des voies traitées.

Il existe aussi de nombreux cas de mortalité d'oiseaux le long des routes où du sel a été répandu. La plupart des cadavres trouvés concernent des passereaux de la famille des Carduélinés (roselins, linottes, sizerins...), peut-être à cause de leur comportement alimentaire hivernal (ils recherchent alors leur nourriture sur le sol, dans des endroits dégagés) et de leur comportement grégaire à cette période.

Ces espèces granivores sont particulièrement attirées par les granules de sel, certainement pour satisfaire des besoins en oligo-éléments (comme c'est le cas des perroquets ingérant de l'argile, lireLa géophagie chez les perroquets). Des chercheurs de la station biologique de l'université du Montana observent par exemple régulièrement des troupes de Roselins de Cassin (Carpodacus cassinii), de Becs-croisés des sapins (Loxia curvirostra), de Tarins des pins (Carduelis pinus) et de Gros-becs errants (Coccothraustes vespertinus) se rassemblant sur de petites zones sans végétation riches en sels minéraux. Des becs-croisés ont aussi été vus buvant de l'eau de mer.

Ces oiseaux peuvent également prendre ces grains de sel pour de petits cailloux (des gastrolithes, ou "grit") qu'ils stockent dans leur gésier (jusqu'à leur usure complète) pour broyer leurs aliments (lireLe système digestif des oiseaux).

Tous ces petits oiseaux meurent généralement suite à des collisions avec les véhicules, mais aussi à cause de la toxicité du sel ingéré en trop grande quantité. Une étude canadienne menée sur le Moineau domestique (Passer domesticus) et publiée en 2005 dans le Journal of Wildlife Diseases avait montré que l'ingestion de quelques granules de sel suffisait à provoquer un empoisonnement. Dans un article publié en 2014 dans la revue Ardea, des ornithologues tchèques ont décrit un cas de mortalité groupée de Tarins des aulnes (Carduelis spinus) : ils avaient mangé des gros granules de sel qu'ils avaient pris pour des cailloux, et des analyses cliniques ont montré qu'ils avaient été intoxiqués.

La difficulté à repérer les cadavres et le faible taux de signalement suggèrent que le nombre de passereaux qui meurent à cause du salage des routes est sûrement sous-estimé. Une solution possible serait notamment de ne répandre que des grains de sel de très petite taille (moins de 2 mm) pour éviter qu’ils ne soient pris pour des gastrolithes.



2014/08/07

Giant penguin fossil shows bird was taller than most humans



Iturria: The Guardian

Analysis of 37m-year-old fossil unearthed in Antarctica shows species would have dwarfed today’s biggest living penguins
Emperor Penguin walking on ice in Prydz Bay, eastern Antarctica
Palaeeudyptes klekowskii would have dwarfed today’s biggest living penguin, the emperor penguin. Photograph: Tui De Roy/Corbis
A penguin species that lived millions of years ago would have dwarfed today’s biggest living penguins and stood as tall as most humans, according to analysis of fossils by a team of researchers from the La Plata Museum in Argentina.
Palaeeudyptes klekowskii has already been dubbed the “colossus penguin”, and is the most complete fossil ever uncovered from the Antarctic. The unearthed bones are 37m years old and include the longest recorded fused ankle-foot bone as well as parts of a wing bone.
From those bones, researchers estimated the species would have stood 2m tall from toe to beak tip, and weighed as much as 115kg. Standing normally, beak down, the penguin would have be around 1.6m tall, the team reported in the journal Geobios.
By comparison, the tallest and heaviest living species, the emperor penguin (Aptenodytes forsteri), stands 1.1m high and weighs just under 50kg.
Being of a larger build has its advantages, as bigger penguins could dive underwater to hunt fish for significantly longer periods of time compared to smaller species. A penguin the size of Palaeeudyptes klekowskii could stay underwater for up to 40 minutes.
How the giant penguin would have measured against humans
The bones were found at the La Meseta formation, Seymour Island, which is part of the Antarctic peninsula with a wide range and abundance of penguin bones. In prehistoric times, the region was warmer with 10 to 14 different penguin species living together.
P klekowskii is not the only giant prehistoric penguin to be discovered – in 2007 of a penguin species known as Icadyptes salasi, was found in Peru, living 36m years ago. It had a slightly smaller height of 1.5m.

2013/05/21

Why Penguins Don't Fly - Pottorro kontuak

Iturria: ScienceNOW


Why Penguins Don't Fly

on 20 May 2013, 3:10 PM |  
 
sn-seabirds.jpg
 
March of the penguins. The labored flight of the
thick-billed murre (main image) helps show why 
the Emperor penguin (inset) sticks to walking and 
swimming.
Credit: Kyle H. Elliott; (inset) Copyright Samuel Blanc
 
Long, long ago, O Best Beloved, the ancestor of the penguins could soar through the air. So why did the penguin give up flight? Rudyard Kipling never wrote a Just So story with an answer, but now scientists have one: The penguin doesn't fly because it would rather swim.
A new study of murres, penguinlike seabirds that retain the ability to take wing, shows just how costly and inefficient it is to be both a diver and a flyer. The new findings back the long-held hypothesis that penguins gave up the heavens more than 70 million years ago to become kings of the waves.
"This study contributes a lot by putting hard numbers on the energy costs of moving through both the aerial and aquatic realms," writes Daniel Ksepka of North Carolina State University in Raleigh, who studies penguin evolution and was not involved with the research, in an e-mail.
For insights into why ancestral penguins might have abandoned their command of the air, the researchers turned to the thick-billed murre, Uria lomvia, which nests on cliffs in Alaska, Canada, and other northerly sites. It propels itself through the water with its wings to scoop up krill and plankton, but it also flies—laboriously.
Murres "are awful flyers," says graduate student Kyle Elliott of the University of Manitoba in Winnipeg, Canada, an author of the new paper. "They beat their wings really, really fast, and they're horrible at landing."
To study murres nesting in northern Canada, the researchers carried shotguns loaded with rubber bullets to ward off the local polar bears and lived in a cabin surrounded by an electric "bear fence." Between surprise visits from bears, the scientists lassoed murres and injected them with tracer molecules to track their energy usage. They also outfitted the murres with sensors to learn how deep they dove and how much time they spent in air, underwater, and on land.
The results show that being a murre is hard work. The animals expend more energy per minute of flight than any other bird, surpassing even the previous champion, the bar-headed goose, famed for flying over the Himalayas. On the wing, murres burn energy at 31 times their rate at rest, the highest known ratio in a bird, the team reports today in the Proceedings of the National Academy of Sciences. When other vertebrates are working hardest, they burn energy at only 25 times their resting rate.
Murres fare better in the water, where they're more efficient than many other birds, but they could still use a few tips on their stroke. The researchers found that compared with penguins of the same size, murres expend far more energy while diving, indicating that giving up flight raised their efficiency.
The results show that murres "are really at the edge of what a bird can do," says University of Missouri, St. Louis, seabird ecologist Robert Ricklefs, an author of the paper. If the murre's all-purpose wing became more like a penguin's stubby flipper, swimming would be easier, because a short wing creates less drag in the water. But flying would be nearly impossible, because a short wing makes it harder to stay aloft.
The results run contrary to assumptions that "all birds had the same flight cost, more or less," Elliott says. For murres, "we were able to show that flight costs were much greater than expected … [and] demonstrate the cost of not being flightless." Even so, flight allows murres to flee predators and zip between nest and foraging grounds. For ancestral penguins, on the other hand, flightlessness was apparently a better deal, enabling them to grow larger, helping them dive deeper, swim faster, and stay underwater longer, Ricklefs says. And that meant they nabbed more and bigger prey.
The study provides valuable confirmation of the idea that ancient penguins swapped flight for underwater prowess, known as the tradeoff hypothesis, says Chris Thaxter, a seabird ecologist at the British Trust for Ornithology in Thetford, U.K. "This is a major step forward … in understanding how the tradeoff hypothesis works."

Seabird Bones Reveal Changes in Open-Ocean Food Chain

Iturria: ScienceDaily:

May 13, 2013 — Remains of endangered Hawaiian petrels -- both ancient and modern -- show how drastically today's open seas fish menu has changed.


Excavated bones of Hawaiian petrels – birds that spend the majority of their lives foraging the Pacific – show substantial change in the birds' eating habits. (Credit: Courtesy of Brittany Hance, Imaging Lab, Smithsonian Institution)
A research team, led by Michigan State University and Smithsonian Institution scientists, analyzed the bones of Hawaiian petrels -- birds that spend the majority of their lives foraging the open waters of the Pacific. They found that the substantial change in petrels' eating habits, eating prey that are lower rather than higher in the food chain, coincides with the growth of industrialized fishing.
The birds' dramatic shift in diet, shown in the current issue of the Proceedings of the National Academy of Sciences, leaves scientists pondering the fate of petrels as well as wondering how many other species face similar challenges.
"Our bone record is alarming because it suggests that open-ocean food webs are changing on a large scale due to human influence," said Peggy Ostrom, co-author and MSU zoologist. "Our study is among the first to address one of the great mysteries of biological oceanography -- whether fishing has gone beyond an influence on targeted species to affect nontarget species and potentially, entire food webs in the open ocean."
Hawaiian petrels' diet is recorded in the chemistry of their bones. By studying the bones' ratio of nitrogen-15 and nitrogen-14 isotopes, researchers can tell at what level in the food chain the birds are feasting; generally, the larger the isotope ratio, the bigger the prey (fish, squid and crustaceans).
Between 4,000 and 100 years ago, petrels had high isotope ratios, indicating they ate bigger prey. After the onset of industrial fishing, which began extending past the continental shelves around 1950, the isotope ratios declined, indicating a species-wide shift to a diet of smaller fish and other prey.
Much research has focused on the impact of fishing near the coasts. In contrast, the open ocean covers nearly half of Earth's surface. But due to a lack of historical records, fishing's impact on most open-ocean animal populations is completely unknown, said lead author Anne Wiley, formerly an MSU doctoral student and now a Smithsonian postdoctoral researcher.
"Hawaiian petrels spend the majority of their lives foraging over vast expanses of open ocean," she said. "In their search for food, they've done what scientists can only dream of. For thousands of years, they've captured a variety of fish, squid and crustaceans from a large portion of the North Pacific Ocean, and a record of their diet is preserved in their bones."
Addressing fishery impact through a chronology of bones is remarkable. Most marine animals die at sea, where their bones are buried on the ocean bottom. But after three decades of fossil collection in the Hawaiian Islands -- the breeding grounds of the Hawaiian petrel -- co-author Helen James of the Smithsonian Institution and her colleagues have amassed a collection of more than 17,000 ancient Hawaiian petrel bones.
"The petrels breed in burrows and caves where, if they die, their bones are likely to be preserved for a long time," James said. "It's fortuitous to find such a rich bone record for a rare oceanic predator."
Further studies are needed to explore how the shift down the food chain is affecting Hawaiian petrels. For a coastal seabird, however, a similar shift in diet has been associated with decreases in population -- bad news for a federally protected bird.
Since petrels exploit fishing grounds from the equator to near the Aleutian Islands -- an area larger than the continental United States -- their foraging habits are quite telling. If petrels, signal flares for open-ocean food webs, have had a species-wide change in feeding habits, how many other predators around the world has fishing impacted? And what role do consumers play?
"What you choose to put on your dinner plate -- that's your connection with the endangered Hawaiian petrel, and with many other marine species," Wiley said.
The research was funded by the National Science Foundation, MSU and the Smithsonian Institution.
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Story Source:
The above story is reprinted from materials provided by Michigan State University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. Anne E. Wiley, Peggy H. Ostrom, Andreanna J. Welch, Robert C. Fleischer, Hasand Gandhi, John R. Southon, Thomas W. Stafford, Jr., Jay F. Penniman, Darcy Hu, Fern P. Duvall, and Helen F. James. Millennial-scale isotope records from a wide-ranging predator show evidence of recent human impact to oceanic food webs. PNAS, May 13, 2013 DOI: 10.1073/pnas.1300213110

2013/05/17

Haritzalde 'Talaia' proiektuaren inguruan mintzo

Mezu hau helarazi digu Haritzalde Naturzaleen Elkarteak:




La mejora del GR121 en Mendizorrotz supondría un desastre


Haritzalde no puede aceptar este proyecto


La Asociación Naturalista Haritzalde ha solicitado oficial y formalmente al Ministerio de Medio Ambiente, a la Diputación Foral de Gipuzkoa y al Ayuntamiento de Donostia que aparquen definitivamente el proyecto de supuesta mejora del GR121, debido a los fuertes impactos que ocasionaría y a su desorbitado coste.

4 millones de euros son muchas monedas, y sobre todo en estos días donde la austeridad es mandato presidencial. 4 millones de euros va a recibir el Ayuntamiento de Donostia/San Sebastián, a cambio de “mejorar” el GR121 que transita en su municipio, en el monte Mendizorrotz. Mejorar” llama el Ministerio de Medio Ambiente (contratante en este negocio) a ensanchar y asfaltar (con gravilla) una ruta transitable que discurre por el medio con más biodiversidad del municipio, según un estudio realizado por la Sociedad de Ciencias Aranzadi para el consistorio (www.donostia.org). ¿Qué impacto en el medio natural ejercerá la obra y qué impacto en el medio ambiente tendrán los urbanitas, felices de haber colonizado otra área? No lo sabemos. Lo que sí sabemos con seguridad es que la obra aterradora no cuesta 4 millones de euros.

Nos parece mal y vergonzoso que se gasten 4 millones en algo que no lo vale, no lo necesita y tiene al lado un espacio con necesidad urgente de restauración ambiental, la Cala de Agiti.

Hay numerosas zonas que requieren de inversiones para su restauración y mejora de su estado de conservación: Motondo, cara norte de Mendizorrotz, Ulia, ribera del Urumea... Que empiecen por Agiti. Es necesario invertir en Medio Ambiente, pero exigimos se haga de una forma coherente y sensata. La costa vasca es bella y la transitan un montón de caminos vecinales que no necesitan de gravilla; sin embargo, sí que necesita dinero para su protección, para que siga siendo bella y rica, y no la ensucien con proyectos como el de “mejora” de la GR121.

Por tanto, pedimos que dicho proyecto se aparque para siempre y solicitamos que con ese dinero se inicie, para empezar, la recuperación ambiental de la cala de Agiti, lugar en el que además existió una charca en la que se reproducía la ranita meridional (Hyla meridionalis), catalogada en el País vasco “en peligro de extinción”.


¡RECUPEREMOS AGITI AHORA!