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

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.

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

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

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	44,800 km2	medium
Number of locations	6-10	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	2500-9999 mature individuals	poor	estimated	2016
Population trend	decreasing	poor	inferred	2000-2020
Rate of change over the past 10 years/3 generations (longer of the two periods)	1-9%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	1-9%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	1-9%	-	-	-
Generation length	6.7 years	-	-	-
Number of subpopulations	2-100	-	-	-
Percentage of mature individuals in largest subpopulation	1-89%	-	-	-

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	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Mexico	extant	native	yes

Country/Territory	IBA Name
Mexico	Huayacocotla
Mexico	Sierra Norte de Oaxaca
Mexico	Tlanchinol y Bosques de Montaña del Noreste de Hidalgo

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

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

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Recommended citation
BirdLife International (2024) Species factsheet: Dwarf Jay Cyanolyca nanus. Downloaded from https://datazone.birdlife.org/species/factsheet/dwarf-jay-cyanolyca-nanus 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.