||Ptychoramphus aleuticus (Pallas, 1811)
||Alcita de Cassin, Alcita oscura, Alcuela oscura, Mérgulo sombrío
||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.
||23 cm small, plump alcid. Short blackish/grey bill, base of lower mandible yellowish. Iris white, white crescent above eye. Dark greyish brown head with paler brown chin and throat. Upperparts blackish to slate grey with greyish brown breast and flanks, white belly. Legs and feet bluish pink, with black claws. No marked seasonal variation. Juvenile has whiter throat, browner wings and tail and dark brown iris (Nettleship 1996).
|Red List Category & Criteria:
||Butchart, S. & Symes, A.
||Butchart, S., Calvert, R., Ekstrom, J. & Ashpole, J
This species has been uplisted to Near Threatened because the global population decline is likely to approach 30% in three generations (23 years). If the decline is found to be larger then the species could qualify for further uplisting; it almost meets the requirements for listing as threatened under criteria A2b+3b+4b.
|Previously published Red List assessments:|
- 2015 – Near Threatened (NT)
- 2012 – Least Concern (LC)
- 2009 – Least Concern (LC)
- 2008 – Least Concern (LC)
- 2004 – Least Concern (LC)
- 2000 – Lower Risk/least concern (LR/lc)
- 1994 – Lower Risk/least concern (LR/lc)
- 1988 – Lower Risk/least concern (LR/lc)
|Range Description:||The species ranges from Baja California (Mexico) up the Pacific coast of the U.S.A. and Canada, through Alaska to the Aleutian Islands (U.S.A.) (del Hoyo et al. 1996). British Columbia (Canada) supports the largest population with approximately 2,700,000 breeding birds; it is estimated that there are approximately 600,000 birds in Alaska, 88,000 in Washington, 500 in Oregon, 131,000 in California and 20,000-40,000 in Baja California on the islands of San Benito, San Geronimo, Asuncion and San Roque (Nettleship 1996).|
Canada; Mexico; United States
|♦ Continuing decline in area of occupancy (AOO):||Unknown|
|♦ Extreme fluctuations in area of occupancy (AOO):||No||♦ Estimated extent of occurrence (EOO) - km2:||8620000|
|♦ Continuing decline in extent of occurrence (EOO):||Unknown||♦ Extreme fluctuations in extent of occurrence (EOO):||No|
|♦ Continuing decline in number of locations:||Unknown|
|♦ Extreme fluctuations in the number of locations:||No|
|♦ Upper elevation limit (metres):||100|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The total population is estimated to be at least 3,600,000 breeding birds (Nettleship 1996) which equates to approximately 5,400,000 individuals.|
Trend Justification: This species has apparently undergone a large and statistically significant decrease over the last 40 years in North America (-96.8% decline over 40 years, equating to a -57.9% decline per decade; data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007, although these surveys cover less than 50% of the species's range in North America). A recent study by Rodway and Lemon (2011) found declines in monitored burrows at several colonies in British Columbia, and estimated a 40% decline in monitored burrows over 20 years between 1989 and 2009 in the largest known breeding population on Triangle Island (part of the Scott Islands). Declines appear to have begun in c.1990, and if the declines on Triangle Island are representative of the whole Scott Islands population then there could have been a total loss of approximately 800,000 birds in the region, or >20% of the world breeding population. Large-scale declines have also been documented on the South Farallon Islands, California (H. Carter in litt. 2013). The overall rate of decline is currently placed in the band 20-29% in three generations (23 years), but confirmation that similar declines are taking place across the whole range would lead to the overall rate of decline being increased.
|Current Population Trend:||Decreasing|
|♦ Number of mature individuals:||2500000-4999999||♦ Continuing decline of mature individuals:||Yes|
|♦ Extreme fluctuations:||No||♦ Population severely fragmented:||No|
|♦ Continuing decline in subpopulations:||Unknown|
|♦ Extreme fluctuations in subpopulations:||No||♦ All individuals in one subpopulation:||No|