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Snow Petrel Breeding Biology at an Inland Site in Continental Antarctica
Peter G. Ryan and Barry P. Watkins
Vol. 12, No. 2 (1989), pp. 176-184
Published by: Waterbird Society
Stable URL: http://www.jstor.org/stable/1521338
Page Count: 9
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The breeding biology of Snow Petrels (Pagodroma nivea) at Robertskollen, a group of nunataks (isolated peaks of land) 130 km from the ice-shelf front in western Dronning Maud Land, Antarctica, is compared with breeding biology at coastal sites. The estimated breeding population of 600 pairs is confined to three of five major nunataks. Nunatak structure, specifically the enhanced protection from drift snow at elevated sites, apparently determines colony dispersion. Most birds are small, falling within the size range of the nominate race, but one large individual may be ascribed to the larger race P. n. major. Birds were incubating when the study started; the first chicks were found on 17 January and hatching probably commenced on 15 January, which suggests that egg-laying started at the beginning of December. Capture resulted in at least 44% of incubating birds deserting. Incubation shifts of marked birds averaged 8.4 days (range 6-10, excluding the short pre-hatching shift), and brooding lasted between 6.5 and 8 days in two or three shifts. The duration of incubation and brood shifts are similar to those of nominate race birds breeding at the coast in Princess Elizabeth Land, but are almost twice as long as those of the large race P. n. major breeding at the Adelie Land coast. This racially consistent difference in the duration of incubation and brood shifts, irrespective of colony distance from the sea, lends support to the hypothesis that there were formerly two isolated populations of Snow Petrels.
Colonial Waterbirds © 1989 Waterbird Society