THE LITTLE AUK ALLE-ALLE-POLARIS OF FRANZ JOSEF LAND - A COMPARISON WITH SVALBARD ALLE-A-ALLE POPULATIONS

Breeding biology, nestling growth and development, and biometry of the little auk Alle alle polaris were studied in Franz Josef Land. A tota l of 103 adult birds were measured, 60 in the field and 43 in the St. Petersburg Museum. The development of 16 chicks was compared with that of Alle a. alle chicks from Spitsbergen. At particular stages of deve lopment, both adults and nestlings of A. a. polaris are larger than th ose of A. a. alle. In Franz Josef Land the breeding season is more ext ended and less synchronised than that of Svalbard. The majority of the little auks in the studied colonies in Franz Josef Land nested on ste ep rocky cliffs, possibly as an adaptation to the severe climatic cond itions and heavy mammalian predation in subcolonies located on accessi ble mountain slopes. Glaucous gulls Larus hyperboreus exerted negligib le predatory pressure. This study confirms the existence of morphologi cally distinguishable populations of the little auk on Franz Josef Lan d and Svalbard, supported by recent studies of climatic and oceanograp hic conditions in the two areas that parallel the morphological differ entiation.