ANTARCTIC BIRDS 



Antarctica is a land of ice and sno\v and rock, without "land birds." But the 

 Antarctic seas are rich in marine life, and penguins, petrels, and albatrosses have their 

 headquarters in the southern oceans. Some may be restricted in breeding activities to 

 tiny islands, or to the edge of the Antarctic Continent, but at other times they may 

 range widely. Some may even migrate north across the tropical seas to north tem- 

 perate waters; for example, in the austral winter (our summer) the Wilson's petrel is 

 found in the Atlantic as far north as Labrador and the British Isles. Nor are all the 

 species of these groups southern; a petrel, the fulmar, breeds in Greenland, a penguin 

 is resident in the Galapagos Islands at the equator, and two albatrosses nest on Laysan 

 Island in the North Pacific. 



Antarctic birds do not fit well into the zoogeographical divisions of the rest of the 

 world. Those avifaunas are dependent on factors involving land masses and land con- 

 nections. To the sea birds, which characterize the far southern waters, such things are 

 of small moment. The temperature, salinity, and other aspects of the sea water and 

 ocean currents are important to their distribution, directly or indirectly, and their 

 ranges tend to be concentric bands around Antarctica and at various distances from it. 

 Two zones of surface water, Antarctic and Sub-Antarctic, are sometimes recognized. 

 Though the Antarctic waters are cold (in summer the temperature may get up to only 

 about 37° F. at its northern edge, at about the limit of the floating ice), they are ex- 

 traordinarily rich in nutrient salts, which support a rich phytoplankton — microscopic 

 floating plants — in which diatoms are important. The food chains are short and direct 

 in these icy seas. The diatoms use the nutrient salts from the sea water and radiant 

 energy from the sun; crustaceans, notably some popularly called "opossum-shrimp" or 

 "krill," feed on the plankton; and penguins, petrels, and even whales and one of the 

 seals eat the opossum-shrimp. 



The birds characteristic of the Antarctic zone in the American quadrant, according 

 to Murphy, are four species of penguins, two albatrosses, eight petrels, and a skua. 



The Sub-Antarctic zone of surface water, which surrounds the Antarctic water 

 mass, is warmer, with a summer temperature that may get up to nearly 60° F. in the 

 north. It is saltier, too, but is still high in nutrient salts. Other species of animals occur, 

 and the list of birds is not only longer but includes more types. Characteristic of it are 

 only two penguins, but there are four albatrosses, seventeen petrels, three cormorants, 

 a skua, and a gull. 



A few birds are tolerant enough in their requirements to be restricted to neither zone 

 but are characteristic of both the Antarctic and the Sub-Antarctic. This group includes 

 two penguins, two albatrosses, three petrels, one cormorant, a gull, a tern, and a 

 curious relative of the plovers, the sheath-bill, which is the only bird without webbed 

 feet to reach the Antarctic. 



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