Cassin’s Auklet (Ptychoramphus aleuticus): uplist to Near Threatened or Vulnerable?

This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2014.

BirdLife species factsheet for Cassin’s Auklet

Cassin’s Auklet Ptychoramphus aleuticus ranges from Baja California (Mexico) up the Pacific coast of the USA and Canada, through Alaska to the Aleutian Islands. It is listed as Least Concern on the basis that it was not thought to approach the thresholds for vulnerable under any of the IUCN criteria.

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence of less than 20,000 km2  combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (fewer than 10,000 mature individuals with a continuing decline estimated to be at least 10% over ten years or three generations, or with a specified population structure).

Until recently, the population trend appeared to be decreasing but the decline was not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (at least a 30% decline over ten years or three generations). This species has 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). However, these surveys cover less than 50% of the species’ 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 Cassin’s Auklet burrows over 20 years between 1989 and 2009 in the largest known breeding population on Staple Island. Declines appear to have begun in c.1990, and could equate to a total loss of approximately 800,000 birds in the region, or >20% of the world breeding population. If such declines are similar or higher elsewhere within the range, it could qualify for uplisting to Near Threatened or Vulnerable under criterion A2b of the IUCN Red List, based on a global population decline approaching or exceeding 30% in three generations (estimated at 23 years for this species).

Further information is requested on population trends from other parts of this species’s range.


Butcher, G. S. and Niven, D. K. (2007) Combining data from the Christmas Bird Count and the Breeding Bird Survey to determine the continental status and trends of North American birds. National Audobon Society: New York, USA.

Rodway, M. S. and Lemon, M. J. F. (2011) Use of permanent plots to monitor trends in burrow-nesting seabird population in British Columbia. Marine Ornithology 39: 243–253.

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  1. Archived 2011-2012 topics: Greater Scaup (Aythya marila): uplist to Near Threatened or Vulnerable?
  2. Archived 2011-2012 topics: The effects of projected climate change on the Southern Ocean and Antarctic environment: uplist Emperor Penguin (Aptenodytes forsteri) to Vulnerable and Adelie Penguin (Pygoscelis adeliae) to Near Threatened?
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3 Responses to Cassin’s Auklet (Ptychoramphus aleuticus): uplist to Near Threatened or Vulnerable?

  1. Harry Carter says:

    Similar large-scale declines in Cassin’s Auklets have been documented at the South Farallon Islands, California. These declines likely began in 1970s and 1980s. Recent work has not yet been published. Contact Gerry McChesney for more information.

  2. Andy Symes says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2014 Red List is to pend the decision on Cassin’s Auklet Ptychoramphus aleuticus and keep this discussion open until early 2015, while leaving the current Red List category unchanged in the 2014 update.

    There is now a period for further comments until the final deadline of 31 March, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Andy Symes says:

    Recommended categorisation to be put forward to IUCN

    Following further review, there has been no change to our preliminary proposal for the 2014 Red List status of this species.

    This discussion will remain open for further comments and information until early 2015, and the current Red List category will remain unchanged in 2014.

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