• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic source(s)
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.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	A2bce+3bce+4bce	A2bce+3bce+4bce

Red List history

Year	Category	Criteria
2020	Endangered	A2bce+3bce+4bce
2018	Endangered	A2bce+3bce+4bce
2016	Endangered	A2bc+3bc+4bc
2012	Endangered	A2bc+3bc+4bc
2010	Endangered	A2c; A3c; A4c
2008	Endangered	A2c; A3c; A4c
2005	Endangered
2004	Endangered
2000	Vulnerable
1994	Not Recognised
1988	Not Recognised

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)	4,790,000 km2	medium
Extent of Occurrence (non-breeding)	6,800,000 km2	medium
Number of locations	11-100	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	240000-280000 mature individuals	medium	estimated	2015
Population trend	decreasing	medium	estimated	2002-2024
Rate of change over the past 10 years/3 generations (longer of the two periods)	50-79%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	50-79%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	50-79%	-	-	-
Generation length	7.15 years	-	-	-
Number of subpopulations	2-100	-	-	-

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 15,400-23,900 individuals in Washington, Oregon and California (Falxa et al. 2014, Falxa and Raphael 2016). This range equates to 238,800-278,300 mature individuals, rounded here to 240,000-280,000. The latest estimate from Partners in Flight (2019) suggests a population of mature individuals of 260,000.

Trend justification: The population was estimated to have declined by c.11% in 2000-2013 in Washington, Oregon, and California (Falxa et al. 2014), with a 50% decrease in Alaska in 1972-1992 (Piatt and Naslund 1995). Although population declines in Oregon and California are reported to have been stabilising in recent years (Falxa and Raphael 2016, A. Burger in litt. 2020), declines have continued in Washington State with adult Murrelet densities declining on the shores of the San Juan Islands from 11.16 to 5.76 individuals/km² between 1995-2012, mirroring declines witnessed by large-scale at-sea surveys (Lorenz and Raphael 2018). Population declines in Washington are currently estimated at ~4.6% per year (Falxa and Raphael 2016). 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 with declines in some regions of British Columbia (COSEWIC 2012, Bertram et al. 2015). 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). Overall declines are suspected to be very rapid and on-going due to very low measured productivity rates.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Canada	extant	native	yes	yes	yes
Mexico	extant	vagrant			yes
USA	extant	native	yes	yes	yes

Country/Territory	IBA Name
Canada	Barkley Sound
Canada	Cleland Island and Southeast Clayoquot Sound
Canada	Desolation Sound
Canada	Nootka Island banks
USA	Ano Nuevo Area
USA	Cape Blanco Nearshore Ocean
USA	Cape Meares Marbled Murrelet
USA	Central CA MAMU
USA	Del Norte Coast
USA	Glacier Bay & Icy Strait
USA	Half Moon Bay, CA MAMU
USA	Humboldt Bay
USA	Humboldt Lagoons
USA	Icy Bay
USA	Kachemak Bay
USA	Klamath, CA MAMU
USA	Marbled Murrelet IBA
USA	North Olympic Marbled Murrelet
USA	Olympic Coast Marbled Murrelet
USA	Olympic Continental Shelf
USA	Pelican Bay, CA MAMU
USA	Point No Point
USA	Port Angeles Marbled Murrelet
USA	Port Snettisham
USA	Prince William Sound
USA	Samish/Padilla Bays
USA	Skagit Bay
USA	Stephens Passage & Tracy-Endicott Arms
USA	Uganik Bay & Viekoda Bay

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	Pelagic	suitable	resident
Marine Oceanic	Epipelagic (0-200m)	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		Occasional altitudinal limits

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		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses 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
		Stresses Ecosystem degradation, Reduced reproductive success
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Indirect ecosystem effects, Reduced reproductive success
Human intrusions & disturbance	Recreational activities	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Indirect ecosystem effects, Reduced reproductive success
Human intrusions & disturbance	Work & other activities	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species disturbance, Reduced reproductive success
Invasive and other problematic species, genes & diseases	Problematic native species/diseases	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Reduced reproductive success
Pollution	Industrial & military effluents - Oil spills	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Reduced reproductive success, Species mortality

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Recommended citation
BirdLife International (2024) Species factsheet: Marbled Murrelet Brachyramphus marmoratus. Downloaded from https://datazone.birdlife.org/species/factsheet/marbled-murrelet-brachyramphus-marmoratus on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 23/11/2024.