|Scientific Name:||Rissa brevirostris|
|Species Authority:||(Bruch, 1853)|
|Red List Category & Criteria:||Vulnerable A2ac+3c+4ac ver 3.1|
|Contributor(s):||Artukhin, Y., Renner, H. & Williams, J.|
|Facilitator/Compiler(s):||Benstead, P., Butchart, S., Gilroy, J., Pilgrim, J., Taylor, J.|
This species is listed as Vulnerable owing to a rapid population reduction in the last three generations (44 years). Trends in the main population appear to have stabilised and, unless declines recommence the species may warrant downlisting to Near Threatened in future.
|Range Description:||Rissa brevirostris breeds in the Pribilof (St Paul, St George and Otter), Bogoslof (Bogoslof and Fire) and Buldir (Buldir, Outer Rock, Middle Rock) islands, USA, and the Commander Islands (Arij Kamen, Toporkov, Bering and Mednyi), Russia. In 1990s, small breeding colonies were also discovered on Unalga, Koniuji and Amak Islands (Aleutians) (J. Williams in litt. 2007). From the mid-1970s to mid-1990s, the known population declined by c.35%. Most of this decline was on the Pribilofs: a precipitous c.44% in breeding numbers on St George, where over 80% of the 1970s population bred. The small population on St Paul declined by 55%. The population on St George has apparently now stabilised at c.123,000 birds (Dragoo et al. 2000, Dragoo et al. 2001). The second largest colony on Bering Island contained 12% of the population in the mid-1970s but the decline on the Pribilofs had increased this to 18% by the mid-1990s. There is some evidence of a historic decline on the Commander Islands, but no counts are available prior to the late 1980s and numbers have remained stable from the mid 1990s to 2007 (J. Williams in litt. 2007). No other colony holds more than 2% of the population, but the number of nests had increased threefold on the Bogoslof Islands and twofold on Buldir Island by the mid-1990s (Byrd et al. 1997). There are an estimated 160,000-180,000 breeding adults in Alaska (Kushlan et al. 2002) and 17,000 pairs in the Commander Islands, Russia, (del Hoyo et al. 1996), which gives a global population estimate of 337,000-377,000 mature individuals.|
Native:Canada; Russian Federation; United States
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||There are an estimated 160,000-180,000 breeding adults in Alaska (Kushlan et al. 2002) and 17,000 pairs in the Commander Islands, Russia, (del Hoyo et al. 1996), which gives a global population estimate of 337,000-377,000 mature individuals, and the population is therefore best placed in the band 100,000-499,999 individuals. Brazil (2009) has estimated the population in Russia at c.100-10,000 breeding pairs and c.50-1,000 individuals on migration.|
|Habitat and Ecology:||This species nests in colonies on ledges on vertical sea cliffs, and feeds on small fish (e.g. lampfish), squid and marine invertebrates (Byrd and Williams 1993). Birds arrive at nesting colonies in April and leave around September, dispersing southwards over the north-east Pacific and east to the Gulf of Alaska (Byrd and Williams 1993).|
The reasons for the population decline remain unclear, but it has been attributed to a reduction in food supply resulting from excessive commercial fishing. Shifts in the distribution of prey fish species, resulting from climate change and rising sea temperatures, may also contribute to current and future declines (Anon 2006). The recent construction of a harbour in the Pribilof Islands considerably increases the chances of the accidental introduction of rats which would pose a serious threat (Byrd and Williams 1993). The species is potentially threatened by climate change because it has a geographically bounded distribution: its global distribution is restricted to within c.10o latitude from the polar edge of continent and within which 20-50% of current vegetation type is projected to disappear under doubling of CO2 levels (Birdlife International unpublished data). The on-going decline on St Paul could be partly caused by subsistence offtake (H. Renner in litt. 2012).
Conservation Actions Underway
It is a protected species in both the USA and Russia. The Alaska Maritime National Wildlife Refuge and Commander Islands Nature and Biosphere Reserve protect many of the breeding colonies. A rat prevention programme is underway in the Pribilof Islands (Byrd and Williams 1993). Conservation Actions Proposed
Monitor breeding populations to assess decline rates. Assess the status of rats at breeding colonies. Assess the impact of commercial fishing. Establish the proposed buffer zone around the Pribilof Islands in which trawl fishing would be prohibited (Lensink 1984).
|Citation:||BirdLife International 2013. Rissa brevirostris. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 03 July 2015.|