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Marbled Murrelet Brachyramphus marmoratus

IUCN Red List Criteria

Critically Endangered  
Endangered A2bc+3bc+4bc 
Vulnerable A2bc+3bc+4bc 

IUCN Red List history

Year Category
2012 Endangered
2010 Endangered
2008 Endangered
2005 Endangered
2004 Endangered
2000 Vulnerable
1994 Not Recognised
1988 Not Recognised

Species attributes

Migratory status not a migrant Forest dependency High
Land mass type continent
shelf island
Average mass 220 g


  Estimate Data quality
Extent of Occurrence breeding/resident (km2) 1,380,000 medium
Extent of Occurrence non-breeding (km2) 1,380,000 medium
Number of locations 11-100 -
Fragmentation -

Population & trend

  Estimate Data quality Derivation Year of estimate
No. of mature individuals medium Estimated 2012
Population trend Decreasing medium -
Number of subpopulations 2-100 - - -
Largest subpopulation 1001-10000 - - -
Generation length (yrs) 12.1 - - -
Population justification: COSEWIC (2012) estimated the total population to number 358,200-417,500 individuals, rounded here to 350,000-420,000 individuals, based on 271,000 individuals in Alaska (Piatt et al. 2007), 72,600-125,600 in British Columbia (Bertram et al. 2007), and 14,631-20,952 individuals in Washington, Oregon and California (Falxa et al. 2009).
Trend justification: The population was estimated to have declined by c.15% in 2000-2007 in Washington, Oregon, and California (Falxa et al. 2008), with a 50% decrease in Alaska in 1972-1992 (Piatt and Naslund 1995) and a 29% decrease in 2001-2010 (Falxa et al. 2011), and 40% in some parts of British Columbia in 1982-1992 (Kelson et al. 1995). At-sea surveys over the past 25 years in British Columbia suggest declines of c. 1% per year (Piatt et al. 2006) although radar surveys suggest the population may have been relatively stable since 1999 (COSEWIC 2012). Availability of nesting habitat in British Columbia, which is strongly correlated with local breeding populations (Burger 2001, Burger et al. 2004), has declined by 22%  between  1978 and 2008 and is continuing (COSEWIC 2012). Declines are suspected to be very rapid and on-going due to very low measured productivity rates.

Country/Territory distribution

Country/Territory Occurrence status Presence Breeding Non-breeding Passage Resident
Canada Native Extant     Yes Yes
Mexico Vagrant Extant   Yes    
USA Native Extant Yes      

Important Bird Areas where this species has triggered the IBA criteria

Country/Territory IBA Name IBA link
Canada Barkley Sound site factsheet
Canada Cleland Island and Southeast Clayoquot Sound site factsheet
Canada Desolation Sound site factsheet
Canada Nootka Island banks site factsheet
USA Ano Nuevo Area site factsheet
USA Del Norte Coast site factsheet
USA Humboldt Bay site factsheet
USA Humboldt Lagoons site factsheet
USA Icy Bay site factsheet
USA Kachemak Bay site factsheet
USA Marbled Murrelet IBA site factsheet
USA Olympic Continental Shelf site factsheet
USA Port Snettisham site factsheet
USA Prince William Sound site factsheet
USA Skagit Bay site factsheet
USA Uganik Bay & Viekoda Bay site factsheet

Habitats & altitude

Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Temperate major breeding
Marine Coastal/Supratidal Coastal Brackish/Saline Lagoons/Marine Lakes suitable non-breeding
Marine Neritic Macroalgal/Kelp major resident
Marine Neritic Pelagic suitable resident
Marine Neritic Seagrass (Submerged) major resident
Marine Neritic Subtidal Loose Rock/pebble/gravel major resident
Marine Neritic Subtidal Rock and Rocky Reefs major resident
Marine Neritic Subtidal Sandy major resident
Marine Neritic Subtidal Sandy-Mud major resident
Marine Oceanic Epipelagic (0-200m) suitable non-breeding
Marine Oceanic Mesopelagic (200-1000m) suitable non-breeding
Wetlands (inland) Permanent Freshwater Lakes (over 8ha) major non-breeding
Wetlands (inland) Permanent Freshwater Marshes/Pools (under 8ha) major non-breeding
Altitude 0 - 0 m Occasional altitudinal limits  

Threats & impact

Threat (level 1) Threat (level 2) Impact and Stresses
Biological resource use Fishing & harvesting aquatic resources / Unintentional effects: (large scale) [harvest] Timing Scope Severity Impact
Ongoing Whole (>90%) Slow, Significant Decline Medium Impact: 7
Indirect ecosystem effects, Reduced reproductive success, Species mortality
Biological resource use Logging & wood harvesting / Unintentional effects: (large scale) [harvest] Timing Scope Severity Impact
Ongoing Majority (50-90%) Very Rapid Declines High Impact: 8
Ecosystem degradation, Reduced reproductive success
Invasive and other problematic species, genes & diseases Problematic native species/diseases Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Decline Medium Impact: 6
Reduced reproductive success
Pollution Industrial & military effluents / Oil spills Timing Scope Severity Impact
Ongoing Whole (>90%) Slow, Significant Decline Medium Impact: 7
Ecosystem degradation, Reduced reproductive success, Species mortality

Recommended citation
BirdLife International (2015) Species factsheet: Brachyramphus marmoratus. Downloaded from on 28/04/2015. Recommended citation for factsheets for more than one species: BirdLife International (2015) IUCN Red List for birds. Downloaded from on 28/04/2015.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Endangered
Family Alcidae (Auks)
Species name author (Gmelin, 1789)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 1,380,000 km2
Country endemic? No
Links to further information
- Summary information on this species