Bicknell's Thrush Catharus bicknelli


Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - A2bc+3bc+4bc

Red List history
Year Category Criteria
2020 Vulnerable A2bc+3bc+4bc
2018 Vulnerable A2c+3c+4c
2016 Vulnerable A2c+3c+4c
2012 Vulnerable A2c+3c+4c
2008 Vulnerable A2c; A3c; A4c; B1a+b(i,ii,iii,iv,v)
2004 Vulnerable
2000 Vulnerable
1994 Not Recognised
1988 Not Recognised
Species attributes

Migratory status full migrant Forest dependency High
Land mass type Land-mass type - continent
Average mass -

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 790,000 medium
Extent of Occurrence non-breeding (km2) 511,000 medium
Number of locations 11-100 -
Severely Fragmented -
Population and trend
Value Data quality Derivation Year of estimate
No. of mature individuals 80000 medium estimated 2016
Population trend Decreasing poor inferred -
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 1 - - -
Percentage in largest subpopulation 100 - - -

Population justification: Hill and Lloyd (2017) estimate there to be 71,318 individuals (c. 56,080-89,748) in the U.S.A. whilst COSEWIC (2009) suggested a population of 40,570 and 49,258 individuals in Canada. This suggests a population size between 111,888 and 120,396 individuals, similar to the overall population sizes suggested by IBTCG (2010), 95,000-126,000 individuals and Hill and Lloyd (2017), <120,000 individuals. The population is therefore assumed to comprise fewer than 120,000 individuals, or 80,000 mature individuals.

Trend justification: Breeding population trend data for the species are sparse, but generally indicate declines, especially in core and northern parts of the range. The State of the Mountains Birds Report (2020) suggests an annual decline of ~2.41% per year throughout the USA (c. 60% of the species's population), which equates to a decline of ~21.6% over a ten year period (Hill 2020). Much more rapid declines have however, been noted throughout parts of the species's breeding range in recent years with rates of 7-19% noted (IBTCG 2010), including declines of 16% and 11% per year in New Brunswick and Nova Scotia, Canada respectively between 2002 and 2010 (Campbell 2011). Therefore, as declines appear to be rapid and those in Canada may well outweigh those of the USA, the species is precautionarily assumed to be declining at a rate in excess of 30% per decade, placed here in the range, 30-49%.

Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Canada N Extant Yes
Cuba N Extant Yes
Dominican Republic N Extant Yes
Haiti N Extant Yes
Jamaica N Extant Yes
Puerto Rico (to USA) N Extant Yes
USA N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Canada Nepisiguit Highlands
Canada Mount Carleton Provincial Park
Canada Cape North
Canada St. Paul Island
Canada Scatarie Island
Canada Cape Breton Highlands National Park
Canada Central Cape Breton Highlands
Canada Prince Edward County South Shore
Canada Massif du mont Gosford
Canada Mont Mégantic
Canada Monts Chic-Chocs
Canada Charlevoix
Dominican Republic Sierra de Bahoruco National Park
Dominican Republic Haitises National Park
Dominican Republic Honduras
Dominican Republic Loma Guaconejo
Dominican Republic Parque Nacional Montaña La Humeadora
Dominican Republic Nalga de Maco-Río Limpio
Dominican Republic Cotubanamá
Dominican Republic Loma Quita Espuela
Dominican Republic Sierra Martin Garcia National Park
Dominican Republic Parque Nacional Dr Juan Bautista Pérez Rancier (Valle Nuevo)
Dominican Republic Armando Bermudez National Park
Puerto Rico (to USA) Vieques
Puerto Rico (to USA) Suroeste
Puerto Rico (to USA) Karso del Norte
Jamaica Blue Mountains
Haiti Aux Diablotins
Dominican Republic Sierra de Neyba
Haiti Aux Cornichons
Haiti Aux Becs-Croisés
Cuba Turquino - Bayamesa
USA High Elevation Spruce-Fir
USA Adirondack High Peaks Forest Tract
USA Catskills Peaks Area
USA Northern Adirondack Peaks
Haiti Massif de la Hotte
Haiti Massif de la Selle
Cuba Cordillera del Turquino y zona costera El Macío - Las Coloradas
Dominican Republic Ebano Verde Scientific Reserve
USA Northern Green Mountains IBA

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Rural Gardens suitable non-breeding
Forest Subtropical/Tropical Moist Lowland suitable non-breeding
Forest Subtropical/Tropical Moist Montane major non-breeding
Forest Temperate major breeding
Altitude 350 - 2200 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Small-holder farming Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Ecosystem degradation, Ecosystem conversion
Biological resource use Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest] Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Ecosystem degradation
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Future Whole (>90%) Unknown Unknown
Ecosystem degradation
Human intrusions & disturbance Recreational activities Timing Scope Severity Impact
Future Unknown Unknown Unknown
Species disturbance
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus rattus Timing Scope Severity Impact
Ongoing Unknown Unknown Unknown
Species mortality
Pollution Air-borne pollutants - Acid rain Timing Scope Severity Impact
Past, Likely to Return Whole (>90%) Slow, Significant Declines Past Impact
Ecosystem degradation
Residential & commercial development Tourism & recreation areas Timing Scope Severity Impact
Past, Likely to Return Minority (<50%) No decline Past Impact
Ecosystem degradation, Ecosystem conversion

Recommended citation
BirdLife International (2021) Species factsheet: Catharus bicknelli. Downloaded from on 27/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from on 27/10/2021.