Bylot Island is located at the south-eastern corner of the Lancaster Sound along the northern edge of Baffin Island. Navy Board Inlet, Eclipse Sound, and Pond Inlet separate Bylot Island from the much larger Baffin Island to the south and west. Much of Bylot Island is characterized by glaciers and mountains that rise to an elevation of 1900 metres above sea level. A rolling outwash plain occurs on the southwest corner of the island, directly north of Eclipse Sound. Glacial rivers have dissected the plain, which rises about 60 metres above sea level and slopes gradually upwards to the mountains. The vegetation on the plain is dominated by low shrub-herb, and shrub-sedge tundra. In the river valleys, heath, willow, and other flowering plants are more common.
The southwest plain of Bylot Island contains the largest known breeding colony of the Greater Snow Goose (ssp. atlanticus). Nesting colonies of a few pairs to several thousand geese are scattered over the entire plain. Like other populations of white geese in the Canadian Arctic, the Greater Snow Goose population has risen dramatically since the mid 1960s (about 11% annually). The population on South Bylot has experienced similar growth, with 15,100 breeders being recorded in 1983, 26,700 breeders in 1988, and 55,000 breeders in 1993. In all, the 1993 population (including non-breeders and juveniles) was 156,000 birds. The breeders and non-breeders represent about 16% of the estimated 1993 spring population of this subspecies. In 1988, the number of breeding geese on Southwest Bylot represented about 13% of the Greater Snow Goose population.
The southwest Bylot Island breeding bird community has been well studied. Between 1992 and 1997, 31 breeding species were recorded in study plots within the plain. Overall, the most common species were Lapland Longspur, Snow Goose, American Golden Plover, Baird's Sandpiper, and Long-tailed Jaeger. Other species present in relatively larger numbers were Snow Bunting, Horned Lark, American Pipit, and Snowy Owl, the owls only being present during years when lemming numbers were high. The number of species and density of nesting pairs at this site is greater than at all other sites in the Canadian Arctic Archipelago north of 70° latitude where detailed avifaunal surveys have been completed. All of the species identified as being largely restricted to the Arctic Cordillera Biome occur as nesters on the southwest plain, with the exception of Ivory Gull.
BirdLife International (2020) Important Bird Areas factsheet: Southwest Bylot. Downloaded from http://www.birdlife.org on 29/11/2020.