Buteo elegans, Cassin (adult). (Correction and modern nomenclature: Aplomado Falcon, adult, Falco femoralis. Original caption was in error, Buteo elegans refers to another plate from this source, showing a Red-shouldered Hawk, Buteo lineatus.) From: Reports of Explorations and Surveys.... Volume X. 1859 of the U. S. Pacific railroad Explorations and Surveys 38th, 39th, 41st Parallels. Copied from NOAA Photo Library. http://www.photolib.noaa.gov/library/

Source: https://commons.wikimedia.org/wiki/File:Buteo_elegans.jpg

The aplomado falcon (Falco femoralis) is a medium-sized falcon of the Americas. The species' largest contiguous range is in South America, but not in the deep interior Amazon Basin. It was long known as Falco fusco-coerulescens or Falco fuscocaerulescens, but these names are now believed to refer to the bat falcon (Falco rufigularis). Its resemblance in shape to the hobbies accounts for its old name orange-chested hobby. Aplomado is an unusual Spanish word for "lead-colored", referring to the blue-grey areas of the plumage – an approximate English translation would be "plumbeous falcon". Spanish names for the species include halcón aplomado and halcón fajado (roughly "banded falcon" in reference to the characteristic pattern); in Brazil it is known as falcão-de-coleira. Order: Falconiformes, Family: Falconidae, Species: Falco femoralis Temminck, 1822