Early movement between the Pacific and and the Atlantic probably happened to the south (since there was no northern opening to the Atlantic), later movements across the Arctic Sea. The extant auks are broken up into 2 main groups, the puffins (subfamily Fraterculini) and auklets (subfamiliy Aethiini), and the Uria guillemots (subfamily Alcini), murrelets and guillemots (subfamilies Cepphini and Brachyrampphini). Compared to other families of seabirds, there are no genera with many species (such as the genus Larus in the gulls, which has 47 species). This is probably a product of the limited range of the family (the most limited of any seabird family), and the periods of glacial advance and retreat that has kept the populations on the move.





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Today, as in thge past, the auks are restricted to cooler northern waters. Their ability to spread further south is restricted as their prey hunting method, pursuit diving, becomes less efficient in warmer waters. The speed at which small fish (which along with krill are the auk's principal food items) can swim doubles as the temperature increases from 5°C to 15°C, with no coresponding increase in speed for the bird. The southernmost auks, in California and Mexico, can survive there because of cold upwellings. The current paucity of auks in the Atlantic (6 species), compared to the Pacific (19-20 species) is considered to be because of extinctions to the Atlantic auks, the fossil records shows there were many more species in the Atlantic during the Pliocene. Auks also tend to be restricted to continental shelf waters and breed on few oceanic islands.

The Above Images From U.S. Fish and Wildlife Service






















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