Grand Manan Island is a large, often foggy, island situated on the western side of the mouth of the Bay of Fundy. This IBA encompasses: a ten kilometre band of open water around the island, Old Proprietor Shoals, all the smaller islands in the archipelago, and a one kilometre strip of coastal land along Grand Manan Island. The 10 km strip may be more than is necessary to encompass important bird use, especially on the west side, but has been used here due to insufficient knowledge of pelagic bird use. Old Proprietor Shoals are found off the southeastern side of the archipelago, as are other relatively shallow waters. The northern and western sides of the island are bordered by high cliffs, while the eastern shores are composed of boulders, cobbles and a few sand beaches. Many of the smaller islands in the archipelago are rocky, but Grand Manan Island itself is a diverse mix of wetland and forested habitats.
Of the many noteworthy species found in the archipelago, perhaps the most notable is the Razorbill. In winter, recent research has shown that very large numbers of Razorbills have been found in the Old Proprietor Shoals area, and off the north and south heads of Grand Manan. Razorbills are present in variable numbers all winter, but the highest number recorded was an estimated 52,000 birds observed in January, 1998. This number equals at least a third of the North American Razorbill population. Prior to this, anecdotal reports suggested that at least 25,000 birds wintered in the area, but typical wintering numbers are still not well known.
As recently as 1980, up to 100,000 phalaropes - mostly Red-necked Phalaropes - were reported in the waters around Grand Manan Island . Since then such large numbers have not been recorded, and the reasons for the decline are not known. Other pelagic birds that feed in these waters include thousands of Greater, Shearwaters and Wilsons Storm-Petrels (10,000 of the latter in July 1997).
Coastal-feeding migrants, such as most shorebirds, are common in migration. Probably at least 10,000 shorebirds (a nationally significant number) can be found along the coastal parts of this site in the fall although total numbers have not been systematically counted. One species often found in large numbers is the Semipalmated Plover. The surveyors of the multi-day Maritime Shorebird Survey noted that in some years 1,000 birds utilized Kent Island alone (perhaps 2% of the global population). Black-bellied Plover, Greater Yellowlegs, and Least Sandpiper are also common species.
In the late winter and early spring Brant are found by the thousands along parts of the coast, especially at: the west side of Kent Island, Cow Passage, Grand Harbour, around Low Duck Island, and in Castalia Provincial Park. Probably at least 1% of the North American Brant population are found here typically (3000 birds), but 10,000 were recorded in April, 1997.
In addition to Razorbills, a few other species winter in notable numbers. Over 350 Purple Sandpipers gather on the rocky shores in small to medium sized flocks. This number is about 3% of North American population of the species. Great Black-backed Gull numbers can also be high (826 were counted in Dec 1997), Common Eiders are common in winter, and the nationally endangered Harlequin Duck is sometimes seen in large numbers (43 off White Head Island). Small numbers of Dovekies, Common Murres, and numerous other species can also be seen in this season.
Kent Island supports a large breeding colony of Herring Gulls which seems to have been declining over the years. A rough estimate of 25,000 pairs comes from earlier in the century, 1,441 pairs were present in 1984, and in 1998, 940 pairs were present. This colony plus others on other islands (including Great Duck, Sheep and West Green islands) total 1910 pairs, or 1.5% of the North American population. In the early 1980s, about 900 pairs of Common Eiders nested on Kent Island (approximately 1% of the dresseri subspecies population), and in addition more eiders nest in other parts of the IBA. About 1000 pairs of Leachs Storm-Petrels also breed here. In total, about 200 bird species have been recorded on this small island.
Grand Manan also hosts large landbird concentrations during migration. On Grand Manan Island, Castalia Marsh, South Head, and North Head are of particular importance to landbirds. The adjacent Kent Island is also used as a landfall by migrating landbirds.
BirdLife International (2022) Important Bird Areas factsheet: Grand Manan Archipelago. Downloaded from http://www.birdlife.org on 15/08/2022.