Data Zone
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.
| Critically Endangered | Endangered | Vulnerable |
|---|---|---|
| - | - | A2bc+3bc+4bc |
| 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 |
| Migratory status | full migrant | Forest dependency | high |
| Land-mass type |
continent |
Average mass | - |
| Estimate | Data quality | |
|---|---|---|
| Extent of Occurrence (breeding/resident) | 790,000 km2 | medium |
| Extent of Occurrence (non-breeding) | 511,000 km2 | medium |
| Number of locations | 11-100 | - |
| Severely fragmented? | no | - |
| Estimate | Data quality | Derivation | Year of estimate | |
|---|---|---|---|---|
| Population size | 80000 mature individuals | medium | estimated | 2016 |
| Population trend | decreasing | poor | inferred | 2015-2025 |
| Rate of change over the past 10 years/3 generations (longer of the two periods) | 30-49% | - | - | - |
| Rate of change over the future 10 years/3 generations (longer of the two periods) | 30-49% | - | - | - |
| Rate of change over the past & future 10 years/3 generations (longer of the two periods) | 30-49% | - | - | - |
| Generation length | 2.4 years | - | - | - |
| Number of subpopulations | 1 | - | - | - |
| Percentage of mature individuals 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 | Presence | Origin | Resident | Breeding visitor | Non-breeding visitor | Passage migrant |
|---|---|---|---|---|---|---|
| Canada | extant | native | yes | |||
| Cuba | extant | native | yes | |||
| Dominican Republic | extant | native | yes | |||
| Haiti | extant | native | yes | |||
| Jamaica | extant | native | yes | |||
| Puerto Rico (to USA) | extant | native | yes | |||
| USA | extant | native | yes |
| 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 |
| 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 | ||||||
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| 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 | ||||||
|
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| Climate change & severe weather | Habitat shifting & alteration | Timing | Scope | Severity | Impact | ||||
| Future | Whole (>90%) | Unknown | Unknown | ||||||
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| Human intrusions & disturbance | Recreational activities | Timing | Scope | Severity | Impact | ||||
| Future | Unknown | Unknown | Unknown | ||||||
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| Invasive and other problematic species, genes & diseases | Invasive non-native/alien species/diseases - Rattus rattus | Timing | Scope | Severity | Impact | ||||
| Ongoing | Unknown | Unknown | Unknown | ||||||
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| Pollution | Air-borne pollutants - Acid rain | Timing | Scope | Severity | Impact | ||||
| Past, Likely to Return | Whole (>90%) | Slow, Significant Declines | Past Impact | ||||||
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| Residential & commercial development | Tourism & recreation areas | Timing | Scope | Severity | Impact | ||||
| Past, Likely to Return | Minority (<50%) | No decline | Past Impact | ||||||
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Recommended citation
BirdLife International (2024) Species factsheet: Bicknell's Thrush Catharus bicknelli. Downloaded from
https://datazone.birdlife.org/species/factsheet/bicknells-thrush-catharus-bicknelli 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.