Oasis hummingbird

The oasis hummingbird has three subspecies, the nominate R. v. vesper, R. v. koepckeae, and R. v. atacamensis. ==Description==

The oasis hummingbird is long and weighs about . Both sexes have a long, black, decurved bill. The nominate subspecies is larger and has a longer and stouter bill than the other two, but the three are otherwise alike. Both sexes have olive green upperparts with a cinnamon rump and uppertail coverts. Females have a small white dot behind the eye and males a longer white stripe. Males have an iridescent gorget that ranges from rosy violet to purple with turquoise to the rear. Their underparts are dull white with a dull green wash on the flanks. The tail is deeply forked; its central feathers are grayish olive and the rest purplish brown. Females do not have the colorful gorget; their underparts are pale gray to pale buff with darker flanks. Their tail is shorter than the male's and only slightly forked. The tail's upper surface is olive green to bronzy green and all but the central pair of feathers have a wide black bar near the end and white tips. ==Distribution and habitat==

Subspecies R. v. koepckeae of the oasis hummingbird is known only from its type locality in northwestern Peru's Department of Piura. The nominate R. v. vesper is found from just south of there through Peru into Chile's Tarapacá Region. R. v. atacamensis is found further south in Chile between the Atacama and Santiago Metropolitan regions. Their range expansion south of Atacama has occurred since the 1960s. The species inhabits a variety of coastal and near-coastal landscapes including arid scrublands and their oases, riparian zones, agricultural areas, and gardens. In elevation it ranges from near sea level to but in most of Peru it is mostly found below . ==Behavior==

Movement The oasis hummingbird is not known to migrate or make other large-scale movements, but because it has colonized isolated oases and valleys it must make at least exploratory movements. It might also make seasonal elevational changes. Little else is known about the oasis hummingbird's breeding phenology. It possibly nests throughout the year, though nests with eggs are known in Chile only between September and December. The cup nest is suspended from a tree or shrub branch. The clutch size is two eggs. Captive females have incubated the eggs for about 16 days, and fledging occurred about 27 days after hatch. Vocalization The oasis hummingbird's vocalizations have not been extensively recorded. What appears to be its song is "tzee-tzee-dee-dee, first ascending, then descending". Calls include a "melodious series of tick and tzee notes given at variable speeds and tone", "a rapid, thin liquid chatter", and ""a rich chew note". ==Status==

The IUCN has assessed the oasis hummingbird as being of Least Concern. It has a large range, and though its population size is not known, it is believed to be stable. Its range and habitat have supported humans for millennia, so "at least in the short term [the species] seems to be little affected by human activities." ==References==