The least bittern (Ixobrychus exilis) is a small heron, the smallest member of the family Ardeidae found in the Americas. Taxonomy The least bittern was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the herons, cranes, storks and bitterns in the genus Ardea and coined the binomial name Ardea exilis. Gmelin based his description on the "minute bittern" from Jamaica that had been included by the English ornithologist John Latham in his multi-volume work A General Synopsis of Birds. Latham did not specify how he had obtained the specimen. The least bittern is now one of ten species placed in the genus Ixobrychus that was introduced in 1828 by the Swedish naturalist Gustaf Johan Billberg. The genus name combines the Ancient Greek ixias, a reed-like plant and brukhomai, to bellow. The specific epithet exilis is Latin meaning "little" or "slender". Six subspecies are recognised: I. e. exilis (Gmelin, 1789) – Breeding: east Canada and east, southwest USA. Non-breeding: Central America and West Indies I. e. pullus Van Rossem, 1930 – northwest Mexico I. e. erythromelas (Vieillot, 1817) – east Panama and north South America to north Bolivia and north Argentina I. e. limoncochae Norton, DW, 1965 – east Ecuador I. e. bogotensis Chapman, 1914 – central Colombia I. e. peruvianus Bond, J, 1955 – west central Peru North American birds were formerly divided into two subspecies, eastern (I. e. exilis) and western (I. e. hesperis), but this is no longer believed to be a valid distinction. The least bittern forms a superspecies with the little bittern and yellow bittern. Cory's least bittern A dark rufous morph, I. e. neoxenus, termed "Cory's bittern" or "Cory's least bittern" was originally described by Charles Cory as a separate species in 1885 from a specimen collected on or near the Caloosahatchee River, near Lake Okeechobee, in southwest Florida. Cory stated that the specimen was "without doubt perfectly distinct from any other known species". Further specimens followed over the next decades from Florida, Michigan, Illinois, Wisconsin, Ohio, and Ontario. Initially, Cory's least bittern was accepted as a valid species, with Elliott Coues and Richard Bowdler Sharpe both including it in published species lists. As early as 1892, however, doubts were raised about the validity of Cory's least bittern as a separate species. Nonetheless, in 1896 Frank Chapman