The American green kingfishers are the

kingfisher Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found in the tropical regions of Africa, Asia, and Oceania, ...

genus ''Chloroceryle'', which are native to tropical

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known a ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...

, with one species extending north to south

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

Species

There are four species: The American green kingfishers breed by streams in forests or

mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...

s, nesting in a long horizontal tunnel made in a river bank. They have the typical kingfisher shape, with a short tail and long bill. All are plumaged oily green above, and the underpart colour shows an interesting pattern insofar as the smallest and second largest, American pygmy kingfisher and green-and-rufous kingfisher, have rufous underparts, whereas the largest and second smallest, Amazon kingfisher and green kingfisher, have white underparts with only the males also having a rufous breast band. These birds take

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

s and

fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

caught by the usual kingfisher technique of a dive from a perch or brief hover, although the American pygmy kingfisher will hawk at

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

s in flight.

Evolutionary history

These

water kingfisher The water kingfishers or Cerylinae are one of the three subfamilies of kingfishers, and are also known as the cerylid kingfishers. All six American species are in this subfamily. These are all specialist fish-eating species, unlike many repre ...

s are descended from a common ancestor which seems to have been closely related to a progenitor of the pied kingfisher (which at that stage had not yet lost the metallic plumage tone), and are similar in plumage and habits (Moyle, 2006). All four have overlapping ranges, and may fish the same waters; however the weight ratio of ''aenea'': ''americana'': ''inda'': ''amazona'' is almost exactly 1:2:4:8, which prevents direct competition for food. The

ringed kingfisher The ringed kingfisher (''Megaceryle torquata'') is a large, conspicuous and noisy kingfisher bird commonly found along the lower Rio Grande valley in southeasternmost Texas in the United States through Central America to Tierra del Fuego in Sout ...

, ''Megaceryle torquata'', a more distant relative, also occurs on the same rivers, but is twice as heavy as the Amazon kingfisher. Genetically, the largest species, ''C. amazona'', is the most distantly related, while the medium-sized (but differently colored) ''C. americana'' and ''C. inda'' are sister species. The differing coloration therefore does not indicate their evolutionary history, but rather seems to have evolved independently, to underscore the visual distinctness between taxa, thus helping to keep their

gene pool The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species. Description A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can surv ...

s separate (''see also''

Competitive exclusion principle In ecology, the competitive exclusion principle, sometimes referred to as Gause's law, is a proposition that two species which compete for the same limited resource cannot coexist at constant population values. When one species has even the sligh ...

References

* * Fry, K & Fry, H. C. (2000): ''Kingfishers, Bee-eaters and Rollers''. * * {{Taxonbar, from=Q860908 *