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Tuesday Tetrapod: Diomedea exulans

Posted by tigerhawkvok on February 16, 2010 18:43 in tuesday tetrapod

Covering tetrapods is amusing. I want to try for some sort of balance, but there isn't one — about 55% of my entries should be birds, 20% amphibians, 15% non-avian sauropsids, and 10% mammals. I should keep that in mind as I continue to post, and particularly put up more amphibians. That being said, let's work on that 15%, and bring forth Diomedea exulans, or the Wandering Albatross.

D. exulans

D. exulans. Picture by Flickr user AngrySunBird (full)

A procellariiform (tube-nose) water bird, like other albatrosses (diomedeidae), they have characteristically stiff wings they use to "dyanimcally soar", utilizing winds close to the surface of the sea. Procellariiformes are almost exclusively pelagic, with an uncharacteristically good sense of smell for avians. D. exulans are among the largest birds in the world, with definitively the longest wingspan. Average wingspans run 2.5-3.5 m, with largest verified reports running to 3.7 m and questionable sources reporting as much as 5.3 m wingspans. Other adaptations include the ability to excrete excess salt from glands in their nasal passage

D. exulans on the water

Picture CC-BY-NC-SA by Flickr user Arthur Chapman (full)

D. exulans is a distinctive bird with a characteristic beak shape, and mostly white except for black-tipped wings, with some black along the trailing wing feathers as adults.

Like other procellariiformes, D. exulans is long-lived and has a distinctive breeding behaviour. They typically lay only one egg per two years, maintaining a monogamous, lifelong relationship with one other bird. Their breeding population is restricted to three primary sites, with 20% on South Georgia, 40% on Crozet and Kerguelen islands, and 40% on Prince Edwards Islands. This behaviour leaves them particularly vulnerable to cats and rats introduced onto these islands by humans, which cause large problems for eggs and chicks. Particularly on Kerguelen, some breeding colonies have had complete breeding failure due to cats. As a k-selected species, they are sensitive to this sort of predation, with reproduction not occuring until individuals are 11-15 years of age.

D. exulans in flight

Picture CC-BY-NC by Flickr user marj k (full)

During the year, D. exulans is widely distributed, essentially cosmopolitian between 28deg-60deg in the southern oceans. Their wide distribution and their diet of cephalopods, fish, and crustaceans means they are strongly affected by longline fishing used to catch tuna and Chilean Sea Bass. The birds are prone to drowning after becoming ensnareed in the hooks along the lines. A survey in 2007 indicated about half of the chicks on Bird Island have ingested fishing hooks.

They are rated IUCN "vulnerable", with a >30% population decline over the past three generations. Efforts are underway by some fisheries to reduce albatross bycatch.


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freedom mentor

freedom mentor | 03/03/2015 06:47

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freedom mentor | 03/03/2015 06:44

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Tuesday Tetrapod: Diomedea exulans | The Dichotomous Trekkie 2.0