The genus Chloroceryle was introduced in 1848 by the German naturalist Johann Jakob Kaup.

[3] Kaup did not specify a type species but Richard Bowdler Sharpe designated the American pygmy kingfisher in 1871.

The American green kingfishers breed by streams in forests or mangroves, nesting in a long horizontal tunnel made in a river bank.

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 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 pools separate (see also Competitive exclusion principle).