Taxonomy
A species placed in the genus Haliaeetus (sea eagles) which gets both its common and scientific names from the distinctive appearance of the adult's head. Bald in the English name is derived from the word piebald, and refers to the white head and tail feathers and their contrast with the darker body. The scientific name is derived from Haliaeetus, New Latin for "sea eagle" (from the Ancient Greek haliaetos), and leucocephalus, Latinized Ancient Greek for "white head," from λευκος leukos ("white") and κεφαλη kephale ("head").
The Bald Eagle was one of the many species originally described by Linnaeus in his 18th century work Systema Naturae, under the name Falco leucocephalus.
There are two recognized subspecies of Bald Eagle:
- H. l. leucocephalus is the nominate subspecies. It is separated from H. l. washingtoniensis at approximately latitude 38° N, or roughly the latitude of San Francisco. It is found in the southern United States and Baja California.
- H. l. washingtoniensis, synonym H. l. alascanus Townsend, 1897, the northern subspecies, is larger than southern nominate leucocephalus. It is found in the northern United States, Canada and Alaska. This subspecies reaches further south than latitude 38° N on the Atlantic Coast, where they occur in the Cape Hatteras area.
The Bald Eagle forms a species pair with the Eurasian White-tailed Eagle. This species pair consists of a white-headed and a tan-headed species of roughly equal size; the White-tailed Eagle also has overall somewhat paler brown body plumage. The pair diverged from other Sea Eagles at the beginning of the Early Miocene (c. 10 Ma BP) at the latest, but possibly as early as the Early/Middle Oligocene, 28 Ma BP, if the most ancient fossil record is correctly assigned to this genus. The two species probably diverged in the North Pacific, as the White-tailed Eagle spread westwards into Eurasia and the Bald Eagle spread eastwards into North America.
Read more about this topic: Bald Eagle