VU
Aleutian Tern Onychoprion aleuticus



Taxonomy

Taxonomic note
Onychoprion aleuticus (del Hoyo and Collar 2014) was previously placed in the genus Sterna as S. aleutica.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls#.
Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - A2bcde+3cde+4bcde

Red List history
Year Category Criteria
2018 Vulnerable A2bcde+3cde+4bcde
2017 Vulnerable A2bcde+3cde+4bcde
2016 Least Concern
2012 Least Concern
2009 Least Concern
2008 Least Concern
2004 Least Concern
2000 Lower Risk/Least Concern
1994 Lower Risk/Least Concern
1988 Lower Risk/Least Concern
Species attributes

Migratory status full migrant Forest dependency Does not normally occur in forest
Land mass type Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 6,660,000
Extent of Occurrence non-breeding (km2) 225,000
Number of locations -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 31000 poor estimated 2015
Population trend Decreasing estimated -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) 30-49 - - -
Decline (10 years/3 generation past and future) 30-49 - - -
Number of subpopulations - - -
Largest subpopulations - - -
Generation length (yrs) 10.9 - - -

Population justification: Previous published population estimates for Alaska ranged from 9,000 to 12,000 birds, and estimates for Russia ranged from 7,200 to 13,000, although they were based on data that are more than 20 years old (H. Renner in litt. 2013). Wetlands International estimated a total population of 17,000-20,000 individuals, including 9,500 birds in Alaska (Wetlands International 2014), based on data from the U.S. Fish and Wildlife Service (2006), and the total population was therefore placed in the range 11,000-13,000 mature individuals. A subsequent range-wide assessment of population and trends estimated a minimum worldwide breeding population of 31,131 birds across 202 colonies, with 18% (5,529 birds in 110 colonies) in Alaska and 82% (25,602 birds in 92 colonies) in Russia (Renner et al. 2015). It does not account for colonies that have not been surveyed in recent years or for the fact that the surveys conducted were neither systematic nor inclusive of all potential habitats (Renner et al. 2015) and thus the total population may be higher. Based on the minimum total recorded by Renner et al. (2015), the global population estimate has therefore been revised to 31,000 mature individuals.

Trend justification:

Numbers at known colonies in Alaska have declined 8.1% annually since 1960 or 92.9% over three generations (33 years; 95% CI = 83.3%–97%), with large colonies experiencing greater declines than small colonies . Trends at known colonies within discrete geographic regions of Alaska (Aleutian Islands, Bering Sea, Chukchi Sea, Gulf of Alaska and Kodiak Island) were consistently negativeIt is possible that observed trends in Alaska could be explained by the establishment of large, undiscovered colonies in new locations within Alaska, or major shifts between Alaska and Russia, but at present this seems unlikely. The geographic distance would be far greater than any typical breeding dispersal distance of other tern species, and there is no precedence for terns to move their established breeding sites in a biased direction from such a wide geographic scale. All the recently discovered colonies in Alaska are of small size, and unless there are some major colonies remaining to be discovered, it is unlikely to account for the observed declines (M. Rauzon / Pacific Seabird Group in litt. 2017). 

Quantitative trend information from the colonies in the Russian Far East remains lacking, but declines have been reported in several colonies in the Anadyr and Chukotka region (C. Zockler in litt. 2014). However, numbers in some regions in Russia appear to have increased substantially in recent decades, especially on Sakhalin Island and the southern coast of the Koryak Highland (Renner et al. 2015). 

It is difficult to determine the overall trend, but it is unlikely that the extremely rapid declines observed in Alaska have been outweighed by the trend in Russia and a rapid overall decline is therefore suspected to be taking place.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Canada N Extant Yes
Hong Kong (China) N Extant Yes
Indonesia N Extant Yes
Japan N Extant Yes
Malaysia N Extant Yes
Philippines N Extant Yes
Russia N Extant Yes
Russia (Asian) N Extant Yes
Singapore N Extant Yes
United Kingdom V Extant
USA N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Russia (Asian) Bol'shaya River Estuary
Russia (Asian) Korfa Gulf (northern part)
Russia (Asian) Kronotskiy Gulf
Russia (Asian) Nerpich'ye Lake and Kamchatka River delta
Russia (Asian) Nevskoye Lake
Russia (Asian) North-east Sakhalin lagoons
Russia (Asian) Schast'ya Gulf
Russia (Asian) Shantarskiye Islands
Russia (Asian) Udskaya Bay
USA Blacksand Spit Colony
USA East Copper River Delta Colonies
USA Eastern Kodiak Island Marine
USA Entrance Point Colony
USA Goodnews Bay Colony
USA Nelson Lagoon Colonies
USA Noatak River Delta Colony
USA Riou Spit Colony
USA Safety Sound
USA Tiedeman Slough Colony

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Grassland Tundra suitable breeding
Marine Intertidal Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc major breeding
Marine Intertidal Shingle and/or Pebble Shoreline and/or Beaches major breeding
Marine Neritic Pelagic suitable non-breeding
Marine Neritic Pelagic suitable breeding
Marine Oceanic Epipelagic (0-200m) suitable non-breeding
Rocky areas suitable breeding
Wetlands (inland) Bogs, Marshes, Swamps, Fens, Peatlands suitable breeding
Altitude   Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Biological resource use Hunting & trapping terrestrial animals - Intentional use (species is the target) Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Reduced reproductive success
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Ongoing Whole (>90%) Unknown Unknown
Stresses
Indirect ecosystem effects, Ecosystem degradation, Reduced reproductive success
Human intrusions & disturbance Recreational activities Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Species disturbance, Reduced reproductive success
Human intrusions & disturbance Work & other activities Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Species disturbance
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Canis familiaris Timing Scope Severity Impact
Ongoing Minority (<50%) Unknown Unknown
Stresses
Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus norvegicus Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Vulpes lagopus Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Vulpes vulpes Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Reduced reproductive success, Species mortality

Recommended citation
BirdLife International (2019) Species factsheet: Onychoprion aleuticus. Downloaded from http://www.birdlife.org on 21/09/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/09/2019.