The White-tailed Hillstar (Urochroa bougueri) is a species of hummingbird

Hummingbird

Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings...

 in the Trochilidae family, and the only member of the genus Urochroa. It is found in humid montane

Montane

In biogeography, montane is the highland area located below the subalpine zone. Montane regions generally have cooler temperatures and often have higher rainfall than the adjacent lowland regions, and are frequently home to distinct communities of plants and animals.The term "montane" means "of the...

 forest in southern Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, Ecuador

Ecuador

Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

, and northern Peru

Peru

Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

. It has two subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

, the nominate on the west Andean slope, and leucura on the east Andean slope. The two differ strongly, most conspicuously in that the former has a broad orange malar, which the latter lacks. Both have a straight black bill, greenish upperparts, a blue throat, grey belly, and extensive white to the tail. Although sharing the name hillstar with the members of the genus Oreotrochilus

Oreotrochilus

The hillstars are several species of hummingbirds from the genus Oreotrochilus...

, they are quite different and not closely related.