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Location Canada, Nova Scotia
Central coordinates 60o 22.96' West  46o 22.59' North
IBA criteria A4i
Area 1,100 ha
Altitude 0 - 20m
Year of IBA assessment 2008

Bird Studies Canada/Nature Canada

Site description The Bird Islands are located in northeastern Cape Breton Island, approximately 4 km off Cape Dauphin. They consist of two long, narrow islands that are oriented in a northeast/southwest straight line. Hertford Island, located closest to shore, is approximately 1.1 km long and about 120 m wide. Ciboux Island, which is located directly northeast of Hertford Island, is slightly larger, being approximately 1.6 km long and about 120 m wide. Steep twenty-metre high cliffs, with numerous holes and ledges, ring the perimeters of both islands. The vegetation consists of stunted shrubs along with areas of grass and other forbs. These grassy tops were formerly grazed by herds of sheep. Numerous reefs and rock clusters are located between the two islands.

Key Biodiversity The Bird Islands support the largest colony of Great Cormorants in North America. A three-year average, using the 3 most recent years that the area was surveyed, was 565 nesting pairs. These do not reflect exact numbers, since the individual birds move frequently when surveys are being conducted. If approximately accurate, this number represents as much as 9% of the western Atlantic (North American) population.

Although Great Cormorants often breed inland in Europe and Asia, they are strictly coastal breeders in North America. Cormorants prefer nest sites that are within commuting range of adequate food resources and safe from terrestrial predators. As a result, isolated islands, and steep rocky cliffs that are within commuting range of adequate food resources, are favoured as nesting sites.

In addition to Great Cormorants, several other seabirds nest on the cliffs the Bird Islands are the largest concentration of Black-legged Kittiwakes, Razorbills and Atlantic Puffins within Nova Scotia. Numbers of the first two species have increased since the 1980s, with an average of 960 kittiwake, 150 Razorbill, and 75 puffin nesting pairs over the last five surveyed years (between 1990-1997). A few hundred nesting pairs of Double-crested Cormorants, over 300 Black Guillemots, and Leachs Storm-Petrels also breed on here.

Other birds that have been observed on the islands include: Spotted Sandpipers, yellowlegs, Cliff Swallows, Herring Gulls, Greater Black-backed Gulls and Starlings.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Great Cormorant Phalacrocorax carbo breeding  1997  415 nests  A4i  Least Concern 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Bird Islands Sites of Ecological Interest 21 protected area contained by site 22  


IUCN habitat Habitat detail Extent (% of site)
Sea Open sea; Sea inlets  80%
Coastline Sea cliffs and rocky shores  20%

Land use

Land-use Extent (% of site)
nature conservation and research major
not utilised major
tourism/recreation minor

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Bird Islands. Downloaded from on 24/10/2016

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