|Scientific Name:||Phoebastria nigripes|
|Species Authority:||(Audubon, 1849)|
Diomedea nigripes nigripes Turbott (1990)
Diomedea nigripes nigripes Stotz et al. (1996)
Diomedea nigripes nigripes Cramp and Simmons (1977-1994)
Diomedea nigripes nigripes Sibley and Monroe (1990, 1993)
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Contributor(s):||Flint, B., Gales, R., Gilman, E., Harrison, C., Lewison, R., Misiak, W., Mitchell, L., Nel, D., Nisbet, I., Phillips, R., Rivera, K. & Shaffer, S.|
|Facilitator/Compiler(s):||Butchart, S., Calvert, R., Small, C., Sullivan, B., Taylor, J. & Symes, A.|
An analysis of recent data suggests that this species's population is not undergoing rapid declines, as once thought, and is either stable or increasing. However, modelling of the likely effects of mortality caused by longline fishing fleets, combined with potential losses to breeding colonies from sea-level rise and storm surges, suggests it is appropriate to precautionarily predict a moderately rapid population decline over the next three generations (56 years), hence its classification as Near Threatened rather than Least Concern.
|Range Description:||Phoebastria nigripes breeds on the Northwestern Hawaiian Islands (USA), the US Minor Outlying Islands and three outlying islands of Japan, colonies having been lost from other Pacific islands (Whittow 1993, Cousins 1998). In total there are estimated to be 64,500 pairs breeding each year (Flint 2007, Naughton et al. 2007) in at least 14 locations. The largest populations are c.24,000 and 21,000 pairs on Midway Atoll and Laysan Island respectively, which together account for 73% of the global population (Flint 2007, Naughton et al. 2007). On Torishima, 914 chicks were reared from 1,219 pairs in 1998, compared with just 20 in 1964 (Cousins and Cooper 2000). The species disperses widely over the northern Pacific Ocean, particularly to the north-east, towards the coastal waters of North America. There have been occasional records in the southern hemisphere (Carboneras 1992b, Fernandez et al. 2001, Hyrenbach and Dotson 2001, BirdLife International 2004, Hyrenbach et al. 2006, S. Shaffer in litt. 2007).|
Native:Canada; China; Guam; Japan; Korea, Republic of; Marshall Islands; Mexico; Micronesia, Federated States of ; Russian Federation; Taiwan, Province of China; United States (Hawaiian Is.); United States Minor Outlying Islands
Present - origin uncertain:Northern Mariana Islands; Palau; Philippines
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Counts in the 2006-2007 breeding season produced population estimates of 64,500 pairs, equivalent to 129,000 breeding individuals (Flint 2007). This estimate is based on standardised surveys at Midway Atoll, Laysan Island and French Frigate Shoals in 2006. These three colonies support 90% of the global breeding population. Estimates for the other colonies are the most recent available (1982-2006). There are c.23 pairs breeding on the Bonin Islands in Japan, and c.400 pairs on islands offshore from Mexico (primarily Isla Guadalupe, 337 pairs estimated in 2005; Hyrenbach and Dotson 2003).|
|Habitat and Ecology:||It breeds on beaches and slopes with little or no vegetation, and on short turf. The species feeds mainly on flying fish eggs, squid, fish and crustaceans (Harrison et al. 1983), but also on fish offal and human refuse (Cousins 1998). During the brooding period, birds at Tern Island forage predominantly within the vicinity of the island. This foraging range expands during the rearing period to include the distant and more productive Californian Current (Hyrenbach et al. 2002).|
Its populations declined significantly owing to feather and egg collecting in the late 1800s and early 1900s, but then recovered during the first half of the twentieth century. Between 1978 and 1992, the population experienced elevated mortality from interactions with high seas drift-nets in the North Pacific (Johnson et al. 1993). Bycatch estimates from driftnets put yearly bycatch (at least in 1990) at c.4,000 birds per year. Currently, the species interacts with longline fisheries in the North Pacific. In 2003, mortality was estimated to be at least 2,000 birds per year in U.S.-based fisheries and a further 6,000 in Japanese/Taiwanese fleets (Lewison and Crowder 2003). Recent estimates indicate a significant reduction in U.S. longline bycatch from previous years that is very likely attributable to the use of effective seabird avoidance measures, with an average of 130 birds killed per year in longline fisheries in Alaska and Hawaii between 2004 and 2006 (K. Rivera in litt. 2007). Bycatch rates in the Japanese and Taiwanese longline fleets are still largely unknown. However, studies on this species have confirmed the impact of fisheries bycatch on survival (Verán et al. 2007) and the annual population growth rate (Niel and Lebreton 2005). Satellite tracking studies show that post-breeding birds disperse over large distances to the oceanographic 'transition zone' where they are susceptible to bycatch in the U.S. and foreign pelagic longline fleets (Hyrenbach and Dotson 2003, BirdLife International 2004, Hyrenbach et al. 2006). Within this area, tracking revealed that fishing effort was heavy in the habitats utilised by the species, and that there may be a male bias in the individuals affected by bycatch.
Storm waves and sea-level rise may represent significant future threats, since the vast majority of the world population nests on islands below 10 m above sea-level. Recent models that consider dynamic wave action predict greater losses than anticipated of nesting habitat at lower values of predicted sea-level rise for several important breeding islands (Storlazzi et al. 2013). These more realistic models, in concert with accelerating sea-level rise, suggest the possibility of repeated catastrophic reproductive failure in the future caused by the loss of nest sites.
Other threats include pollution (including organochlorines and heavy metals) (Jones et al. 1996, Auman et al. 1997, Finkelstein et al. 2007), introduced predators such as the Polynesian rat Rattus exulans (Hasegawa 1984, Jones et al. 2008), plastic ingestion (though this may not affect chick growth rate; I. C. T. Nisbet in litt. 2010) and volcanic eruption on Torishima (Harrison 1990). Oil pollution is no longer considered a likely threat (I. C. T. Nisbet in litt. 2010).
Conservation Actions Underway
All Hawaiian breeding localities are part of the US National Wildlife Refuge system or State of Hawaii Seabird Sanctuaries. In 1991, a 50 Nautical Mile Protected Species Zone was established around the Northwestern Hawaiian Islands. No longline fishing is allowed in this zone. In 2006, the Papahânaumokuâkea Marine National Monument was established. Nearly 80% of the breeding population is counted directly or sampled every year. All sites except one have been surveyed since 1991 (Croxall and Gales 1998). Hawaiian longline fishing vessels are required to use a range of measures to reduce seabird bycatch. In December 2006, the Western and Central Pacific Fisheries Commission passed a measure to require large tuna and swordfish longline vessels to use at least two seabird bycatch mitigation measures when fishing north of 23 degrees North. The FVOA which represents the longlining captains in the halibut and sablefish fisheries along the US West Coast has instructed its members to use streamer lines when fishing in Washington, Oregan and Californian waters. Conservation Actions Proposed
Continue monitoring population trends and demographic parameters. Continue satellite-tracking studies to assess temporal and spatial overlap with longline fisheries. Adopt best-practice mitigation measures in longline fisheries within the species's range. Re-evaluate the location of the current boundary (23o N) for required use of seabird mitigation measures in the U.S. pelagic longline fisheries (Hyrenbach and Dotson 2003).
|Citation:||BirdLife International 2014. Phoebastria nigripes. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 06 July 2015.|
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