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Sunday, 25 August 2013

Forest-Interior Birds May Be Benefiting from Harvested Clearings

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Efforts to conserve declining populations of forest-interior birds have largely focused on preserving the mature forests where birds breed, but a U.S. Forest Service study suggests that in the weeks leading up to migration, younger forest habitat may be just as important.
 

In an article published recently in the American Ornithologist Union's publication The Auk, research wildlife biologist Scott Stoleson of the U.S. Forest Service's Northern Research Station suggests that forest regrowth in clearcuts may be vital to birds as they prepare for fall migration.

The study suggests that declines in forest-interior species may be due in part to the increasing maturity and homogenization of forests. Openings created by timber harvesting may increase habitat for some forest interior birds, according to Stoleson. "Humans have really changed the nature of mature forests in the Northeast," Stoleson said. "Natural processes that once created open spaces even within mature forests, such as fire, are largely controlled, diminishing the availability of quality habitat."

On four sites on the Allegheny National Forest and private timber inholdings in northeastern Pennsylvania, Stoleson set out to learn where the birds spend time after breeding season and what kind of condition are they in leading up to migration. "After the breeding season, birds sing less, stop defending territory, and generally wander. Tracking them is challenging at this point in their life cycle," Stoleson said. Between 2005 and 2008, he used constant-effort mist netting to capture songbirds, band them, determine whether they were breeding or postbreeders, and assess their overall condition, including whether they were building fat deposits and the extent of parasites the birds carried

Out of Africa? New Bamboo Genera, Mountain Gorillas, and the Origins of China's Bamboos

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African mountain bamboos are something of a mystery, as nearly all bamboos are found in Asia or South America. Hidden away up mountains in the tropics where they provide food for gorillas, just as China's bamboos provide food for the Giant Panda, there are apparently only 2 species, and they had not been examined in very great detail, except by the gorillas, see image.

It had been thought that they were very closely related to the hundreds of similar bamboos in Asia, but their respective ranges are separated by thousands of miles. As flowering in bamboos is such a rare event, spreading by seed takes a very long time, and the suspicion arose that they might be old enough to represent new genera, and possibly could even be remnants of the earliest temperate bamboos, which spread to Asia on drifting tectonic plates. A new study published in the open access journal PhytoKeys, studies the diversity and evolution of African bamboo.

Having studied bamboos in the Himalayas extensively, and edited the descriptions of all the bamboos of China for the Flora of China Project of Academia Sinica and Missouri Botanical Gardens, Dr Chris Stapleton turned his attention to the bamboos of Africa. He found that the features of the mountain bamboos were significantly different to those of Asia, and together with the large geographic separation, the differences were sufficient for the recognition of 2 new African genera, now named Bergbambos and Oldeania, after their local names in the Afrikaans and Maasai languages. The species are now Bergbambos tessellata and Oldeania alpina.

Scientists Analyze the Effects of Ocean Acidification On Marine Species

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Ocean acidification could change the ecosystems of our seas even by the end of this century. Biologists at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), have therefore assessed the extent of this ominous change for the first time. In a new study they compiled and analysed all available data on the reaction of marine animals to ocean acidification. The scientists found that whilst the majority of animal species investigated are affected by ocean acidification, the respective impacts are very specific.

The AWI-researchers present their results as an Advance Online Publication on Sunday 25 August 2013 in Nature Climate Change.

The oceans absorb more than a quarter of anthropogenic carbon dioxide emitted to the atmosphere. They form a natural store without which Earth would now be a good deal warmer. But their storage capacities are limited and the absorption of carbon dioxide is not without consequence. Carbon dioxide dissolves in water, forms carbonic acid and causes the pH value of the oceans to drop -- which affects many sea dwellers. In recent years much research has therefore been conducted on how individual species react to the carbon dioxide enrichment and the acidifying water. So far the overall extent of these changes on marine animals has been largely unknown.

Saturday, 24 August 2013

Tiny Fish Make 'Eyes' at Their Killer

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Small prey fish can grow a bigger 'eye' on their rear fins as a way of distracting predators and dramatically boosting their chances of survival, new scientific research has found.
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39 Researchers from Australia's ARC Centre of Excellence for Coral Reef Studies (CoECRS) have made a world-first discovery that, when constantly threatened with being eaten, small damsel fish not only grow a larger false 'eye spot' near their tail - but also reduce the size of their real eyes.
The result is a fish that looks like it is heading in the opposite direction - potentially confusing predatory fish with plans to gobble them up, says Oona Lönnstedt, a graduate student at CoECRS and James Cook University.

For decades scientists have debated whether false eyespots, or dark circular marks on less vulnerable regions of the bodies of prey animals, played an important role in protecting them from predators - or were simply a fortuitous evolutionary accident.

The CoECRS team has found the first clear evidence that fish can change the size of both the misleading spot and their real eye to maximise their chances of survival when under threat.
"It's an amazing feat of cunning for a tiny fish," Ms Lonnstedt says. "Young damsel fish are pale yellow in colour and have this distinctive black circular 'eye' marking towards their tail, which fades as they mature. We figured it must serve an important purpose when they are young."
"We found that when young damsel fish were placed in a specially built tank where they could see and smell predatory fish without being attacked, they automatically began to grow a bigger eye spot, and their real eye became relatively smaller, compared with damsels exposed only to herbivorous fish, or isolated ones.