Black-footed albatross (Phoebastria nigripes) COSEWIC assessment and status report: chapter 2

Executive Summary

Black-footed Albatross
Phoebastria Nigripes

Species information

The Black-footed Albatross (Phoebastria nigripesAudubon 1839) is a relatively small member of the albatross family. Adult birds are completely dusky brown except for a whitish area around the base of the bill and under the eye, and white plumage over the base of the tail and undertail coverts; bill is dark and legs and feet are black. Juvenile birds have darker plumage than adults and lack white upper and undertail coverts. Sexes are similar although males are generally larger than females. Over the past decade, the use of genetic analyses has reawakened earlier controversy regarding classification of the Diomedeidae. Debate continues on the taxonomy of southern hemisphere albatross species but reclassification of the North Pacific albatrosses to the genus Phoebastria from their previous lumping with the southern genus Diomedea is well-supported, based on morphology and behaviour as well as on genetic data.Within Phoebastriathe Black-footed Albatross is a well-established lineage as it diverged from its closest relative, the Laysan Albatross (P. immutabilis), about 7.9 million years ago. For present-day populations of Black-footed Albatross, analysis of mitochondrial DNA indicates significant genetic differentiation between birds breeding in Hawaii and Japan, suggesting that these two populations may be reproductively isolated despite considerable overlap in their at-sea distributions. There is little evidence to indicate the origin of birds visiting Canadian waters, although 13 birds caught as bycatch in a British Columbia-based longline fishery were all found to be of Hawaiian origin.

Distribution

Black-footed Albatross do not nest in Canada. The species currently breeds at 12 established sites worldwide and has recently begun to colonize or re-colonize at least four other localities. Breeding distribution is almost entirely restricted to the Northwestern Hawaiian Islands, where more than 95% of the global population breeds. The majority of the Hawaiian population nests at Midway Atoll and Laysan Island, but lesser colonies occur from Lehua in the main Hawaiian group to Kure Atoll at the western extreme of the Leeward Chain. Smaller colonies are also situated on islands off the coast of Japan. The species has also recently been recorded nesting at Guadalupe, San Benedicto and Clarión Islands in Mexico and has newly recolonized Wake Atoll in the central Pacific.

At sea, Black-footed Albatrosses range throughout the central North Pacific from the tropics to the Bering Sea, and from the west coast of North America to the coasts of China, Japan and the Sea of Okhotsk.This is the most common albatross in the eastern North Pacific but it is relatively scarce in the western sector. Adult birds are concentrated around the colonies during the egg-laying, incubation and chick brooding periods while during chick-rearing breeding adults range at least 4,500 km from the colony to forage in more productive waters towards the west coast of North America.

In Canada, the Black-footed Albatross is the only albatross species seen regularly off thePacific coast.  At-sea observations are recorded for every month of the year from waters off south-western Vancouver Island to Dixon Entrance off the north coast of the Queen Charlotte Islands/Haida Gwaii.The Black-footed Albatross is considered an offshore species but it is commonly seen over waters within a few nautical miles of the British Columbia coast from May to October; during summer an estimated 2,500 birds occur within Canadian waters. Recent data indicate that during the chick rearing stage breeding birds foragein the California Current as far north as British Columbia. Black-footed Albatross numbers peak in Canadian waters during the post-breeding dispersal in August and early September, particularly along the continental shelf break. In late September to October, numbers decline along the British Columbia coast when birds return to their breeding colonies in Hawaii or Japan.

Habitat

Black-footed Albatrosses typically nest on exposed sandy beaches or on the adjacent, sparsely vegetated fringes of low-lying coral and sand islands in the low-latitude Pacific. Breeding territory is confined to the nest site and its immediate vicinity, and is active only during mating and nesting periods. Approximately 35% of the global Black-footed Albatross population breeds at Midway Atoll, a US National Wildlife Refuge (NWR), while similar numbers of birds nest at Laysan Island in the Hawaiian Islands NWR. Most of the remaining US Black-footed Albatross colonies occur on other islands and atolls also within the Hawaiian Islands NWR and the state of Hawaii’s seabird sanctuary system (Kure Atoll); thus the vast majority of the world’s Black-footed Albatrosses nest at protected sites.

Marine habitat use by the Black-footed Albatross is constrained and influenced by life history stages. During the chick brooding stage, birds makerestricted foraging trips over the warm, nutrient-poor oceanic waters in the vicinity of the colony. When chicks are old enough breeding albatrosses expand their foraging range to access the cold, productive coastal waters along the continental shelf of North America, from central California to British Columbia. With the onset of the post-breeding period, Black-footed Albatrosses disperse across the North Pacific, where they use a broad range of oceanic domains characteristic of tropical, sub-tropical, transition zone and sub-arctic waters. Overscales of 10 to 100 km, processes that aggregate prey, e.g., convergence or frontal zones, likely influence the distribution of the Black-footed Albatross. At-sea survey data from Canadian and US pelagic studies show that Black-footed Albatross are most abundant over the outer continental shelf, particularly at the shelf break. This species frequents boundaries between water masses and areas of strong and persistent upwelling. Seamounts may also be important oceanic features for Black-footed Albatrosses.

There is little protection in place for the marine habitat of the Black-footed Albatross, in part because birds use high seas waters outside of national jurisdictions. Throughout their known range, Black-footed Albatrosses also occur within the territorial waters ofCanada, USA, Mexico, China, Guam, Japan, the Republic of Korea, the Marshall Islands, the Federated States of Micronesia, the Northern Mariana Islands, Russia, and Taiwan.

Biology

Black-footed Albatrosses have been studied extensively at their Hawaiian nesting colonies since the 1950s. Behaviour at sea is also relatively well-known as Black-footed Albatrosses have been included in numerous multi-species surveys and studies of seabirds and other marine predators in subsequent decades. Black-footed Albatrosses are monogamous, with a pair bond that remains intact until the death or disappearance of a mate. Adults usually breed at the age of seven or eight. Breeding birds return to the colony in late October and lay a single egg between mid-November and early December; hatching occurs between mid-January and early February. Chicks are fed a diet of flying fish eggs and stomach oil derived from squid. The nestling period lasts 140–150 d with chicks fledging in June or July. Adult and juvenile birds undergo moult at sea during the post-breeding dispersal.

Principal food items for Black-footed Albatrosses consist of flying fish eggs, fish, squid, scavenged offal, and deep-water crustaceans. Birds primarily feed by seizing food items from the surface of the water andscavenging represents an important mode of obtaining prey. Black-footed Albatrosses are well known ship-followers that are drawn to fishing vessels, and this behaviour makes them particularly vulnerable to drowning in longlining and driftnet fisheries, as well as to localized oil spills. Black-footed Albatrosses are long-lived birds, with an average lifespan of 12–40 years.

Population sizes and trends

The current global population of the Black-footed Albatross is estimated at approximately 300,000 individuals. In 2005, the total number of breeding pairs was estimated at 61,141 breeding at 12 colonies, with 21,006 and 21,829 pairs nesting at Laysan Island and Midway Atoll, respectively. The Japanese population consists of approximately 2,450 breeding pairs. The French Frigate Shoals colony, while only one quarter the size of the two largest colonies (Midway and Laysan) has the longest continuous time series of direct nest counts. The number of active nests there declined steadily from 1987 to 1996, following one of the lowest counts at this colony, but numbers steadily increased to reach pre-1985 values in 2005.

Population estimates at Midway and Laysan are by indirect methods prior to 1998 and are not directly comparable with later surveys. Both Laysan Island and Midway Atoll show a relative increase in breeding pairs in the early 1990s, a decline in the mid– late 1990s, and a subsequent increase to early 1990 counts since 2000. The long-term population trends for this species are unclear despite a published estimate of as much as a 60% decline in three generations. Current data suggest that the interannual variability in counts of active nests is extremely high in this species and thus an assessment of the status of the population would vary depending on what time period was examined. Some population projection model results have showed weak to dramatic declines while others show a relatively stable population. Inadequate demographic parameters, as well as information on fisheries effort and bycatch rates in domestic and international fisheries, are serious problems for all population projection models. In January 2006, a draft status assessment using all available data for Laysan and Black-footed Albatross was submitted to the US Fish and Wildlife Service (USFWS). After acceptance and release by the USFWS, it will provide the most comprehensive and up-to-date assessment of population trends for both Laysan and Black-footed albatrosses. There is no specific trends analysis available for Black-footed Albatross in Canadian waters.

Limiting factors and threats

Like most pelagic seabirds, Black-footed Albatross are a long-livedspecies with small clutch size and low fecundity, slow chick growth and lengthy parental care period, delayed age of first breeding, and high adult survival rates, and are thus highly vulnerable to adult mortality. Historically, the greatest threats to the Black-footed Albatross consisted of poaching by feather and egg hunters, with the loss of as many as 300,000 birds per year between the late 1800s and early 1900s. Other important historical threats included alteration of habitat through military occupation and the introduction of domestic rabbits and non-native vegetation, and population control of nesting birds during wartime preparations and subsequent military operations. Being caught as bycatch in longline and driftnet fisheries is the most significant threat to the Black-footed Albatross today. Other current or imminent threats include chronic and catastrophic oil spills; climate change and its interaction with natural climate cycles; heavy loads of chemical contaminants such as organochlorines and heavy metals; plastic ingestion; and invasive alien species including habitat-altering plants as well as vertebrate predators.

While the validity of the worst-case scenario of a 60% decline in three generations is still unclear since the most recent population assessment is not yet available, several facts make it clear that there is justifiable concern for this species: there is a high degree of interannual variability within the number of breeders returning to the colony each year even though long-term averages appear relatively stable; there are multiple documented threats that affect annual adult and chick survival; they are the third-most commonly reported seabird species caught as fisheries bycatch in the North Pacific (and the most commonly reported species in Canadian fisheries); and there is near-unanimous agreement among scientists in the US and Canada that there is a large amount of uncertainty surrounding estimates of mortality in foreign pelagic longline fisheries. Because of the multiple threats, the degree of uncertainty surrounding total mortality, and the high variability in the number of adults returning to breed each year, a precautionary approach is recommended. There is no doubt that sustained adult mortality from human activities can cause severe population declines in long-lived seabirds.

Special significance of the species

Sailors have traditionally viewed albatrosses as kindred spirits or the reincarnated souls of lost shipmates, and sailors today still feel an affinity for these birds that follow in the wake of their vessel. As the most common albatross in the eastern North Pacific, the Black-footed Albatross is of special significance to the mariners who transit these waters. Despite its offshore habits, theBlack-footed Albatross was also known to coastal First Nations, as evidenced by the presence of a name for this species in the Haida lexicon.

The Black-footed Albatross is a top trophic level predator in the marine food web of the North Pacific Ocean. Although this is not a particularly abundant seabird in comparison to other top trophic level species, maintaining albatross populations at or returning them to historical levels is nonetheless part of maintaining a healthy and functioning marine ecosystem in the North Pacific Ocean.

Existing protection

The Black-footed Albatross is protected in Canada under the Migratory Birds Convention Act, 1994 as well as under the British Columbia Wildlife Act. The species is listed as Threatened in Hawaii and in Mexico, and in 2004 the USFWS received a petition to list the Black-footed Albatross as a threatened or endangered species. This petition is now under review by the USFWS. In 2003, the World Conservation Union (IUCN) uplisted the Black-footed Albatross from Vulnerable to Endangered (EN A3bd) on the basis of a projected future population decline >60% over the next three generations (i.e., 56 years), based on the estimated rate of incidental mortality from demersal and pelagic North Pacific longline fisheries. The Black-footed Albatross is also listed under Appendix II of the Convention on Migratory Species, i.e., the Bonn Convention.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions

Wildlife Species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)
A wildlife species that no longer exists.

Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A wildlife species facing imminent extirpation or extinction.

Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)Footnotea
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)Footnoteb
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)Footnotec
A category that applies when the available information is insufficient (a) to resolve a species' eligibility for assessment or (b) to permit an assessment of the species' risk of extinction.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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