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Alder Island (BC139)

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Alder Island (BC139)

Haida Gwaii, Colombie-Britannique

Latitude 52,453°N
Longitude 131,327°O
Altitude 0 - 100m
Superficie 91,68km²

Description du site

Alder Island is located just north of Burnaby Island on the east coast of Moresby Island in Haida Gwaii. The island is characterized by moderate to steep slopes; Western Hemlock mixed with Sitka Spruce and Western Red-cedar comprise the forest, with alder on the island's perimeter. The understory is open moss or bare litter with patches of salal, small areas of spruce seedlings, and patches of grass around the island fringe. This provides prime nesting habitat for burrow-nesting seabirds such as Ancient Murrelets and Cassin's Auklets. The Ancient Murrelets nest throughout the entire forested area of the island, while the Cassin's Auklets nest in a nearly continuous band around the perimeter of the island. Alder Island is also important as a haul-out site for Hair Seals.

The northern shoreline of Burnaby Island is included in this IBA, along with the marine waters within a 5 km radius of Alder Island. These waters are important as feeding areas for seabirds and as staging grounds for Ancient Murrelets during the breeding season. Several other islands (Huxley, Nakons, Koga, Arichika and Section) lie within this area, although they provide habitat for only a few nesting seabirds.

Oiseaux

During 1985, approximately 14,400 pairs of nesting Ancient Murrelets were recorded on Alder (as much as 2.9% of the estimated worldwide population). It is one of the ten largest Ancient Murrelet colonies in British Columbia, and as such supports 5.5% of the estimated national population. Smaller numbers of other seabirds were also recorded during the survey, including Cassin's Auklets (3,200 pairs) and Pigeon Guillemots (74 birds). Fork-tailed and Leach's Storm-Petrel were also present in small numbers.

In addition to the seabirds, Black Oystercatchers nest on the island's shores, and Bald Eagles nest on Alder as well as some of the other islands in the area. During spring migration, concentrations of White-winged and Surf Scoters (single day count of 2,500 birds during surveys in April 1985), occur along the northwestern shore of Burnaby Island. Glaucous-winged Gulls are also present in large numbers, and several hundred Harlequin Ducks feed along the shores of Alder Island during the spring.

Enjeux de conservation

The greatest threat to the Ancient Murrelet and Cassin's Auklet colonies is the arrival of non-native predators (such as raccoons) from adjacent islands. Raccoons are already present on nearby Burnaby and Huxley Islands, as well as on the mainland shores of Moresby Island. There is no evidence of rats being present on the island. Additional threats to the seabird habitat include potential oil spills, and possible disturbance from boaters and visitors to Gwaii Haanas National Park Reserve.

Catégories ZICO Habitats Usages Menaces Potencielles ou Existantes Status de Protection
Guillemot à cou blanc
Nombre Année Saison
28 8001985Été