Pacific coast: potential high-density areas for seabirds

Maps of potential high-density areas for some seabirds on Canada’s Pacific coast.

Warning

The maps provided on this page show areas where seabirds are likely to occur in higher numbers. This information can help you plan your activities to reduce the risk of harming seabirds, such as avoiding these areas. There may be other areas where seabirds congregate that may not have been surveyed or detected.

The dates representing the breeding and non-breeding seasons were chosen for the purposes of data analysis only. Actual breeding times may vary from year to year, and birds sometimes nest outside these dates. Seabird densities also vary within the breeding and non-breeding time periods used in the data analysis.

It is your responsibility to understand the methods used in the analysis, evaluate risks and determine the measures required to avoid harming seabirds.

Albatrosses

During the breeding season (November 1 to July 31), you are more likely to encounter albatrosses (map 1):

• along most of the west coast of Vancouver Island (especially west of La Perouse Bank to approximately Estevan Point)
• on the shelfbreak region west of the Scott Islands
• on the entrance to Queen Charlotte Sound (especially southeast of Kunghit Island)
• in waters west of Frederick and Langara Islands, Haida Gwaii

During the non-breeding season (August 1 to October 31), distribution is similar to the breeding season. You are more likely to encounter albatrosses (map 1):

• on the shelf-break/slope region (especially the La Perouse Bank area)
• on the entrance to Queen Charlotte Sound
• in waters to the west of Langara Island
• on the slope region west of Nootka Sound
• on the edge of Cook Bank
• on the outer shelf and slope northwest of Anthony Island
• west of Learmonth Bank

 

Overall, albatrosses are present at higher densities off Canada’s Pacific coast during the breeding season than the non-breeding season. Density is strongly associated with outer shelf and continental slope waters. The Black-footed Albatross is the most abundant albatross species found in Canadian waters.

Albatross populations vary by season, breeding cycle and species: they can be found within Canada’s Pacific Exclusive Economic Zone, off the coast of British Columbia in all months of the year.

They breed outside of Canada on:

• the Hawaiian Islands
• small islands off the coast of Japan
• small islands off the coast of Mexico

Adults travel great distances to the west coast of North America when seeking food for their young.

Large gulls

During the breeding season (May 1 to August 15), you are more likely to encounter large gulls in two main areas (map 2):

• a broad area west of the entrance to the Juan de Fuca Strait centred on La Perouse Bank
• an area in the southern Strait of Georgia between Victoria and Vancouver

Other areas with somewhat elevated densities include:

• the shelf waters west and north of Cleland Island
• the northern end of Vancouver Island
• the entrance to Queen Charlotte Strait, west of Kunghit Island
• off Forrester Island

During the non-breeding season (August 16 to April 30), you are more likely to encounter large gulls near Glaucous-winged Gull colonies (map 2).

 

Most of the heightened density areas closely reflect the distribution of many large glaucous-winged gull colonies. This is because many seabirds are colonial breeders and may be found foraging relatively close to their nesting colonies during the breeding season.

The average density of large gulls was much higher during the non-breeding season than during the breeding season. The birds also appear to be more widely distributed (further offshore) during the non-breeding season.

This is likely related to the influx of additional Glaucous-winged Gulls and other gull species from outside of British Columbia during the non-breeding season.

Five gull species were included in the analysis. However, the only local coastal breeder in B.C. is the glaucous-winged gull which is present year round on the Pacific coast.

Approximately 29,000 pairs of Glaucous-winged Gull nest in British Columbia. The largest colonies are on: 

• Chain Islets
• Mandarte Island
• Mitlenatch Island
• Cleland Island

The other four large gull species (herring, western, glaucous and Thayer’s gulls) breed elsewhere and are found in marine areas of British Columbia primarily during the non-breeding season.

For this study, the breeding and non-breeding seasons of the Glaucous-winged Gull were used as the breeding and non-breeding seasons for large gulls.

Murres

During the breeding season (April 1 to September 7), you are more likely to encounter murres in (map 3):

• two areas associated with Common Murre colonies (Triangle Island and Forrester Island)
• a triangular area bounded by the entrance to Queen Charlotte Strait, Calvert Island and Cook Bank
• the shelf waters west of Clayoquot Sound
• the eastern part of the Juan de Fuca Strait (south of Victoria)
• areas southwest of Lucy Island and east of Forrester Island

In the non-breeding season (September 8 to March 31), you are more likely to encounter murres (map 3):

• southwest of Estevan Point
• in the area of La Perouse Bank
• at the eastern end of Juan de Fuca Strait
• at the northern extent of the Strait of Georgia

 

Throughout the year, murres prefer inner continental shelf/coastal waters. From July through late September, hundreds of thousands of murres (primarily Common Murres) are present along the west coast of the southern half of Vancouver Island and northern Washington. The number of birds greatly exceeds the breeding population (of Common Murres) in British Columbia and Washington, it is assumed that most of the birds are from colonies along the Oregon coast.

Approximately 4,300 breeding pairs of Common Murres, and possibly a few Thick-billed Murres, nest along the coast of British Columbia.

More than 90% of the common murres nesting in British Columbia breed on Triangle Island.

The remainder breeds in Haida Gwaii or in low numbers on small islands off the west coast of Vancouver Island.

Rhinoceros Auklet

During the breeding season (April 15 to September 15), you are more likely to encounter Rhinoceros Auklets (map 4):

• in the area encompassed by most of Cook Bank and the entrance to Queen Charlotte Strait, reflecting the proximity of large breeding colonies (Pine Island, the Storm Islands and Triangle Island)
• in secondary areas including:
  • the waters off Anthony and Kunghit Islands and adjacent to Lucy Island
  • in the middle of Dixon Entrance

During the non-breeding season (September 16 to April 14), a similar pattern was found for Rhinoceros Auklets, although at lower densities (map 4).

 

Overall, Rhinoceros Auklets are strongly associated with marine areas adjacent to their nesting colonies and appear to favour continental shelf waters.

An estimated 360,000 pairs of Rhinoceros Auklets nest in British Columbia. The largest colonies are on Pine and Storm Islands, Triangle Island, and the Moore Islands.

Methods

We provide maps of potential high-density areas for seabirds taken as fisheries bycatch on Canada’s Pacific coast. These areas were identified by analyzing data from the Pelagic Seabird Survey Database.

Note that all the data were collected through opportunistic surveys (that is, observers went aboard ocean-going vessels when opportunities for doing so were available). Consequently, the survey effort is not evenly distributed. There may be other areas than shown on the maps provided here where seabirds congregate that may not have been surveyed or detected.

Please refer to map 5 for the marine locations and terrestrial locations mentioned in the descriptions on this page.