Habitat
Cloud-forest and the upper reaches of tropical semi-deciduous forest. From 1,300 - 1,950 m, occasionally up to 2,500 m. Also wandering (possibly seasonally) to c.700 m on adjacent mountain slopes.
Mountains of southern Oaxaca (south-central Mexico).
 
Population
Estimated population is 1,000 - 2,499 (2010) and decreasing.
Status EN
Habitat destruction and degradation due to conversion to agriculture is the main threat.
For more information see BirdLife International Species Factsheet.
Voice
Buzzy, chipping notes. A jerky, warbling song.
Oaxaca Hummingbird (Eupherusa cyanophrys) [XC222852]
by Richard C. Hoyer from Pluma Hidalgo, Oaxaca, Mexico (call)
Oaxaca Hummingbird (Eupherusa cyanophrys) [XC96541]
by manuel Grosselet from La Soledad, Oaxaca, Mexico (call)
Subspecies
Forms a superspecies with White-tailed Hummingbird (Eupherusa poliocerca) and Stripe-tailed Hummingbird (Eupherusa eximia) and sometimes regarded as a subspecies of White-tailed Hummingbird (Eupherusa poliocerca), but morphological differences justify status as separate full species.
No subspecies.
Similar Species
Berylline Hummingbird (Amazilia beryllina) which has rufous tail, lacks blue crown and has red lower mandible.
References
See References.