Protecting birds at sea

Seabird populations are threatened by many factors including introduced predators on nesting colonies, contaminants, marine oil pollution and litter, climate change, tourism, disease, and aquaculture activities. Some of the characteristics and behavioral traits of seabirds make them particularly vulnerable to the effects of human activities in the marine environment. For example, many seabird species do not start breeding until they are several years old. Although most seabird species are long-lived, many produce a small number of eggs (or only a single egg) per year and do not necessarily breed every year. This means that the deaths of breeding adults can have a substantial impact on populations over time.

Some of the threats and risks that can result in mortality to seabirds and potentially affect their populations are described below.

Many seabirds congregate in marine areas of high productivity, where there is a greater abundance of food. Fisheries tend to also concentrate their activities in high-productivity areas, as target fish are often found there. Given the higher densities of seabirds and fisheries in these areas, there is an increased chance for birds to have fatal interactions with fishing gear. In addition, many seabirds are attracted to fishing vessels as potential sources of food. This combination of factors, coupled with birds’ specific foraging techniques such as diving and pursuing prey underwater, can result in injury or death to the birds.

The presence of debris in the marine environment, particularly plastics and other non-biodegradable items, can have an adverse effect on seabirds. Seabirds may become entangled in these items and can also confuse them for food. Ingesting debris can cause blockage of the intestinal tract, reduced appetite, and reduced dietary efficiency. It can also lead to the accumulation of some contaminants in the birds’ tissues.

Feathers provide seabirds with waterproofing, insulation and buoyancy, all of which are necessary for their survival. However, if a seabird comes in contact with even trace amounts of oil, the waterproofing properties of the feathers will be destroyed. This can lead to death from hypothermia or drowning. Oiled seabirds that do not die from hypothermia or drowning may die from ingesting petroleum-based oil when they clean their feathers. Birds that do survive being oiled may have reduced life expectancy and reduced breeding success. Seabirds and their populations can be affected by large single-event catastrophic oil spills, as well as by chronic oiling from small-scale discharges of oil-contaminated bilge water or from sources of unknown origin. Moreover, exposure to fish and vegetable oils can be just as deadly to seabirds as petroleum-based oils as they can also disrupt the waterproofing properties of feathers.

Seabirds are attracted to large offshore structures including drilling and production platforms. The birds are attracted by visual cues from the platforms, lighting and flares, and increased concentrations of food near the structures. Birds may be injured or killed when they collide with the platforms or fly into lights or flares. They can also be affected by the thin, barely visible sheens of oil that can form around the platforms.

Albatrosses can be found within Canada’s Pacific Exclusive Economic Zone (EEZ) in all months of the year. They breed outside of Canada on the Hawaiian Islands and on small islands off the coasts of Japan and Mexico. Adults travel great distances to the west coast of North America when seeking food for their young. Two species of albatross have been listed under the Species at Risk Act: the Short-tailed Albatross is listed as Threatened; and the Black-footed Albatross, which is the most abundant albatross species found in Canadian waters, is listed as Special Concern. More information, including status reports and recovery strategies, can be found at the Species at Risk Public Registry.

During the breeding season for albatrosses, several high-density areas were identified along the outer continental shelf and shelfbreak/slope areas (Map 2); notably, along most of the west coast of Vancouver Island (especially west of La Perouse Bank to approximately Estevan Point). Other areas of heightened density were the shelfbreak region west of the Scott Islands, the entrance to Queen Charlotte Sound (especially southeast of Kunghit Island), and waters west of Frederick and Langara Islands, Haida Gwaii.

During the non-breeding season, albatrosses showed a similar pattern as during the breeding season with high-density areas associated with the shelf-break/slope region, notably the La Perouse Bank area, the entrance to Queen Charlotte Sound, and waters to the west of Langara Island (Map 2). Additional high-density areas were the slope region west of Nootka Sound, the edge of Cook Bank, the outer shelf and slope northwest of Anthony Island, and 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, and are strongly associated with outer shelf and continental slope waters.

Of the five gull species included in the analysis, 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 B.C.; the largest colonies are on the Chain Islets, Mandarte Island, Mitlenatch Island, and 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 to define the breeding and non-breeding seasons for large gulls.

During the breeding season for large gulls, two main areas of high-density were identified (Map 3): a broad area west of the entrance to the Juan de Fuca Strait centred on La Perouse Bank, and an area in the southern Strait of Georgia between Victoria and Vancouver. Other areas with somewhat elevated densities included shelf waters west and north of Cleland Island, the northern end of Vancouver Island, the entrance to Queen Charlotte Strait, west of Kunghit Island, and off Forrester Island. The locations of most of these areas of heightened density closely reflect the distribution of many of the large Glaucous-winged Gull colonies. This is due the fact that many seabirds are colonial breeders, and during the breeding season high numbers of individuals may be found foraging relatively close to their nesting colonies.

During the non-breeding season many of the high-density areas were located near Glaucous-winged Gull colonies (Map 3). 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.

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

During the breeding season for murres five high-density areas were identified (Map 4); two were associated with Common Murre colonies (Triangle Island and Forrester Island). High-density areas for murres during the breeding season were situated in a triangular area bounded by the entrance to Queen Charlotte Strait, Calvert Island and Cook Bank; and with shelf waters west of Clayoquot Sound. Other high-density areas were identified at the eastern part of the Juan de Fuca Strait (south of Victoria), and areas southwest of Lucy Island and east of Forrester Island.

In the non-breeding season, murres move into more coastal waters, especially in the southern half of the province (Map 4). High-density areas have been found southwest of Estevan Point, in the La Perouse Bank area, at the eastern end of Juan de Fuca Strait, and 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, and it is assumed that most of the birds are from colonies along the Oregon coast.

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.

During the breeding season for Rhinoceros Auklets, five high-density areas were identified (Map 5). Four of the high-density areas were close to breeding colonies. The most significant high-density area encompassed 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). Other areas of heightened density were the waters off Anthony and Kunghit Islands and adjacent to Lucy Island. The high-density area in the middle of Dixon Entrance may be birds associated with either Forrester Island, where more than 50,000 pairs nest, or with Lucy Island, where more than 25,000 pairs nest.

During the non-breeding season, a similar pattern was found for Rhinoceros Auklets, although at lower densities (Map 5). Notable changes were the observed lower densities at the Cook Bank - Queen Charlotte Sound area, and the heightened densities at the shelf waters off the southwest coast of Vancouver Island. The waters west of Lucy Island remained an area of high concentration. The distribution of Rhinoceros Auklets during the non-breeding season was more restricted than during the breeding season (a similar pattern to that of murres); they occur off the B.C. coast, generally within 100 km of shore.

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

For more information, please contact the Environment and Climate Change Canada Canadian Wildlife Service office in your region.