NT
Dwarf Jay Cyanolyca nanus



Taxonomy

Taxonomic note

Cyanolyca armillata and C. quindiuna (del Hoyo and Collar 2016) were previously lumped as C. armillata following SACC (2005 & updates), Sibley & Monroe (1990, 1993) and Stotz et al. (1996).

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
- - -

Red List history
Year Category Criteria
2019 Near Threatened C2a(i)
2017 Vulnerable A2c+3c+4c
2016 Vulnerable A2c+3c+4c;B1ab(i,ii,iii,iv,v)
2012 Vulnerable A2c+3c+4c;B1ab(i,ii,iii,iv,v)
2008 Vulnerable A2c; A3c; A4c; B1a+b(i,ii,iii,iv,v)
2005 Vulnerable
2004 Vulnerable
2000 Vulnerable
1996 Endangered
1994 Endangered
1988 Threatened
Species attributes

Migratory status not a migrant Forest dependency High
Land mass type Land-mass type - continent
Average mass 41 g
Distribution

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 44,800 medium
Number of locations 6-10 -
Severely Fragmented -
Population and trend
Value Data quality Derivation Year of estimate
No. of mature individuals 2500-9999 poor 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) 1-9 - - -
Decline (10 years/3 generation past and future) 1-9 - - -
Number of subpopulations 2-100 - - -
Percentage in largest subpopulation 1-89 - - -
Generation length (yrs) 6.7 - - -

Population justification: In Hidalgo the population density has been estimated at 4.4 individuals per km2 (M. Martínez-Morales in litt. 2016). Assuming that this density is representative and that only a proportion of its range is occupied, this would equate to a population of c.4,100 individuals; roughly equating to 2,750 mature individuals, here placed in the band 2,500-9,999 mature individuals. Where suitable habitat persists, the species may be locally common. Given the fragmentation of the range, it is assumed that the species forms several small subpopulations.

Trend justification: The population of Dwarf Jay it thought to be in decline, but the rate of decline has not been estimated directly. Tracewski et al. (2016) measured the forest loss within the species’s range between 2000 and 2012 as c. 41 km2. This roughly equates to a rate of forest loss of 2.4% over three generations (20.1 years) for this species. The Dwarf Jay depends on montane forest (Dinerstein et al. 1995, Ponce-Reyes et al. 2012). Therefore, it is conceivable that the rate of population decline is not equivalent, but slightly faster than the rate of deforestation. Nevertheless, it is unlikely that the rate of population decline exceeds 10% over three generations.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Mexico N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Mexico Centro de Veracruz
Mexico Huayacocotla
Mexico Unión Zapoteco-Chinanteca (UZACHI)
Mexico Sierra Norte
Mexico Tlanchinol y bosques de montaña del noreste de Hidalgo

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Subtropical/Tropical Heavily Degraded Former Forest suitable resident
Forest Subtropical/Tropical Moist Montane major resident
Altitude 1400 - 3200 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Scale Unknown/Unrecorded Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Livestock farming & ranching - Agro-industry grazing, ranching or farming Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Livestock farming & ranching - Small-holder grazing, ranching or farming Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
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
Stresses
Ecosystem degradation
Climate change & severe weather Habitat shifting & alteration Timing Scope Severity Impact
Future Whole (>90%) Unknown Unknown
Stresses
Indirect ecosystem effects, Ecosystem degradation
Human intrusions & disturbance Work & other activities Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Species disturbance
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion
Residential & commercial development Tourism & recreation areas Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Stresses
Ecosystem degradation, Ecosystem conversion

Recommended citation
BirdLife International (2021) Species factsheet: Cyanolyca nanus. Downloaded from http://www.birdlife.org on 21/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/10/2021.