The genus Buteogallus was introduced in 1830 by the French naturalist René Lesson to accommodate the rufous crab hawk, which is therefore the type species.^[2][3] The name is a portmanteau of the genus name Buteo introduced in 1779 by Bernard Germain de Lacépède for the buzzards and the genus Gallus introduced in 1760 by Mathurin Jacques Brisson for the junglefowl.^[4] The genus now contains nine species.^[5]

The solitary eagles (formerly Harpyhaliaetus) are a more inland relative of the "black-hawk" group of Buteogallus – in phenotype they are essentially hefty common black-hawks with lighter body plumage and in one species a small crest. Insofar as there are differences in anatomy, these seem to be related to the different prey they hunt (namely reptiles). Together with the savanna hawk, they seem to be close to some species that were uncomfortably placed in Leucopternis. As that genus was apparently polyphyletic, the present article follows a proposal to unite the solitary eagles as well as the slate-colored hawk ("Leucopternis" schistaceus) with Buteogallus, to agree with the morphological and mtDNA sequence data.,^[6][7] with the addition of the white-necked hawk, "Leucopternis" lacernulatus.^[8]

For a long time various systematists have proposed moving the slate-colored hawk to Buteogallus. Together with the crab hawks and solitary eagles form a sequence of plumage patterns that nicely agrees with the DNA-based phylogeny: the slate-colored hawk looks very much like a smaller, shorter-legged and lighter common black hawk. The case of the white-necked hawk is more puzzling. It is visually and ecologically almost identical to the sympatric mantled hawk (Leucopternis polionotus) and some allopatric white hawks (L. albicollis) but differs in tail color. According to the mtDNA data, it is very closely related to the savanna hawk, which is visually dissimilar, appearing like a very light Buteogallus which has an ochre-grey coloration due to abundant pheomelanins. Either there has been strong convergent evolution in plumage and ecology - perhaps a case of mimicry - between the white-necked and the mantled hawks, or the mtDNA data is misleading due to ancient hybrid introgression. In the respect, the white-necked hawk specimen sampled showed indications of heteroplasmy.^[6]

The placement of the peculiarly apomorphic rufous crab hawk in regard to all these birds must be considered unresolved for the time being.^[6]

Fossil record edit

The fossil record of Buteogallus has meanwhile turned out to be quite rich indeed, with many species being erroneously assigned to other genera at first. The genus – like many buteonines of today – probably succeeded earlier birds of prey during the Miocene and never seems to have occurred outside the Americas. From the time of the last ice age, an array of prehistoric species is known, some of them very large. On Cuba, a particularly gigantic species survived deep into the last ice age, but probably not until human settlement.

• †Buteogallus enectus (Middle Miocene; Sheep Creek, Sioux County, USA)
• †Buteogallus sodalis (Middle Pleistocene; Fossil Lake, Oregon) – formerly in Aquila
• †Buteogallus fragilis (Late Pleistocene; Southwestern USA) – formerly in Buteo or Geranoaetus
• †Buteogallus milleri (Late Pleistocene of Southwestern, USA) – formerly in Buteo or Geranoaetus
• †Buteogallus royi (Late Pleistocene of Cuba)
• †Buteogallus borrasi (prehistoric) – formerly in Aquila or Titanohierax
• †Buteogallus daggetti (prehistoric)
• †Buteogallus woodwardi (Late Pleistocene, Southwestern USA) - formerly Amplibuteo
• †Buteogallus hibbardi (Late Pleistocene, Peru) - formerly Amplibuteo
• †Buteogallus concordatus (Late Pliocene of Florida) - formerly Amplibuteo
• †Buteogallus irpus (Late Pleistocene of Cuba and Dominican Republic)