OUTDOOR SCENES - Portrait of an Eastern Screech Owl - Masters of disguise. The Eastern Screech Owl is seen here doing what they do best. You better have a sharp eye to spot these little birds of prey. Okeefenokee Swamp, Georgia, USA. (Photo and caption by Graham McGeorge/National Geographic Traveler Photo Contest) (via National Geographic Traveler Magazine: 2013 Photo Contest - The Big Picture - Boston.com)

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A Strange Bird: Fossils Shed Light on the Origin of the South American Hoatzin

The hoatzin (Opisthocomus hoazin) is the only living representative of a strange group of birds whose genetic relationships have yet to be satisfactorily explained, even with the aid of modern molecular genetic methods. This bird, somewhat reminiscent of a chicken, lives in the tropical rainforests of the northern part of South America. It is the only known avian species that almost exclusively feeds on leaves. In order to enable preprocessing of this rather indigestible food, the crop is extremely large. This has brought about major changes in the skeleton in the region of the pectoral girdle and the sternum. As in mammalian ruminants, the crop contains a rich bacterial and protozoan fauna, which degrades the plant cellulose into components that are more easily digestible for the birds.

Until recently, practically nothing about the evolutionary history of this bird was known. A skull fragment from the mid-Miocene (around 11.8 – 13.5 million years ago) found in Colombia shows that hoatzins once lived west of the Andes, which is not the case today. Apart from this, the specimen yielded little further information, and as it is in poor condition, its identification was subject to some debate.

Then, in 2011, the first fossils that could unequivocally be identified as hoatzin fossils were found in South America by Brazilian colleagues. The finds come from the Tremembé Formation (Oligocene/ Miocene, 22 - 24 million years ago) in Brazil. They belong to a new species, Hoazinavis lacustris, that hardly differs from recent hoatzins except in its smaller size. The fact that the fossil material consisted of parts of the wing and the pectoral girdle was particularly informative, because these are exactly the bones that have a characteristic shape in recent hoatzins on account of the huge crop. As the corresponding skeletal elements of Hoazinavis are practically identical with those of its modern relatives, it may be assumed that the fossil species likewise had a greatly enlarged crop. From this, we deduce that hoatzins have maintained their highly specialized feeding habits for over 20 million years.

Other fossils described in the same study have yielded even more information on the evolution of the hoatzin.These are bones that were attributed as early as 2003 to a new species, Namibiavis senutae, that lived in the early Miocene (17 – 17.5 million years ago) of Arrisdrift in Namibia. The fossils were erroneously assigned to an extinct taxon of the South American seriemas, which were also abundant in Europe during the early Cenozoic Era. In fact, Namibiavis senutae belongs to the hoatzins. The humerus and pectoral girdle of this species have the characteristic morphology of hoatzins and are very similar to the corresponding bones of the Brazilian Hoazinavis. Despite the fact that the African species is more recent, an analysis of the interrelationships showed that Namibiavis senutae has more primitive features than the two more closely related species Hoazinavis lacustris and the extant hoatzin, Opisthocomus hoazin.

(via SENCKENBERG world of biodiversity | Senckenberg Research)

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Conservationists to count breeding birds after ‘puffin wreck’ winter

Nipped fingers and handfuls of guano will be the order of the day for wildlife rangers on the Farne Islands as they embark on an epic census on Friday to discover whether puffin numbers have plummeted after a year of extreme weather.

The 10 National Trust rangers living on the islands must dangle their bare fingers down 60,000 puffin burrows in the next two months to determine whether breeding pairs have fallen after the worst puffin “wreck” for 66 years.

The wreck in March, which saw 3,500 birds wash up dead along the north-east coast of Britain, was caused by icy easterly winds. It followed a summer when the puffins on the archipelago off Northumberland were flooded out of their underground homes, with more than 40% failing to breed….

The census occurs every five years and since it began in 1939, puffin numbers on the Farnes have soared from 3,000 breeding pairs to 36,835 pairs in 2008. But that figure was a 30% fall from the high of 2003, raising fears that the extreme weather and warmer seas brought about by climate change may be affecting the puffins….

Puffins have flourished on the Farnes thanks to the National Trust’s careful management of the 40,000 visitors who take boat trips to the islands each year – and the absence of ground predators. There are no foxes or rats, although wardens are monitoring this carefully after a ship ran aground on the islands in March.

Counting puffins is undertaken by carefully reaching into each burrow with a bare hand so that rangers can gently detect the presence of monogamous pairs and whether they are sitting on an egg.

(via The Guardian)

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