thumb|Male C. a. septentrionalis, Panama
The green kingfisher (Chloroceryle americana) is a species of "water kingfisher" in the subfamily Cerylinae of the family Alcedinidae. It is found from southern Texas in the United States south through Central America, and in every mainland South American country except Chile.
Taxonomy and systematics
The green kingfisher was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the other kingfishers in the genus Alcedo and coined the binomial name Alcedo americana. Gmelin based his description on "Le martin-pêcheur vert et blanc" from Cayenne that had been described and illustrated in 1780 by the French polymath Comte de Buffon and also the "white and green kingfisher" that had been described in 1782 by the English ornithologist John Latham. The green kingfisher is now placed in the genus Chloroceryle that was introduced in 1848 by Johann Jakob Kaup.
A molecular phylogenetic study published in 2006 found that the green kingfisher is a sister species to the larger green-and-rufous kingfisher (C. inda).
Five subspecies are recognized:
Description
The green kingfisher is about long and weighs about ; females are larger and heavier than males. Birds in the northern and southern parts of its range, and those west of the Andes, are larger and heavier than the others, but the differences tend to be clinal. The species has the typical kingfisher shape with long heavy bill (heaviest in Trinidad and Tobago); in contrast to many other kingfishers, however, it does not have an obvious crest. The bill is black with some horn color at the base of the mandible and its legs and feet are dark gray. Both sexes have green upperparts with two or more rows of white spots on the flight feathers. Their underparts are mostly white with green spots on the sides and flanks. Their tail is green with much white on the outer feathers that shows best in flight. Adult males have a white collar and a rufous breast. Adult females have a white collar, a buffy throat and breast, and a band of green speckles across the breast and upper belly. Juveniles resemble females but are duller and have small buff spots on their crown and wing coverts.
Breeding
The green kingfisher's breeding season varies geographically. In Central America it is during the dry season of spring and early summer. In Suriname and Guyana, it usually extends to August and occasionally to December or beyond. Breeding dates further south have not been documented. Both members of a pair excavate a nest burrow, almost always in an earthen bank of a stream or river. It is up to long with a small nest chamber at the end. The clutch size varies from two to six. The incubation period is 19 to 21 days; usually the female incubates at night and the parents alternate during the day. The young fledge 26 to 27 days after hatching and the parents chase juveniles from their territory about 29 days after fledging.