The Blue-capped Hummingbird or `` Oaxaca Hummingbird '' ( Eupherusa cyanophrys ) is a species of hummingbird . The Blue-capped Hummingbird is endemic to subtropical moist forest in the southernmost part of the Sierra Madre del Sur in the Mexican state of Oaxaca . The Blue-capped Hummingbird or Oaxaca Hummingbird ( Eupherusa cyanophrys ) is a species of hummingbird endemic to subtropical moist forest in the southernmost portion of the Sierra Madre del Sur in the Mexican state of Oaxaca .