This bird contrasts with the Northern Harrier in the color of its eyes, which are "orange to reddish brown" (Alsop, p. 121).
It contrasts with the Mississippi Kite in having a "lighter tail, black shoulder patches" (Alsop, p. 122).

"Pale gray above and white below, it has a white head with a small black patch around the eye. Black epaulettes adorn the shoulders ... it was formerly named the white-tailed kite (Elanus leucurus). The AOU, however, now considers it part of a single worldwide complex with the black-winged kite of Africa and Eurasia and the black-shouldered kite of the Australian region. All are collectively designated the black-shouldered kite" (Tveten, 151).

The USGS website adds:

"* White head, chin, throat, chest, belly and underwing coverts
* White underwing with primaries darkening on outer wing
* Small black wrist mark on underprimary coverts
* White tail
* Pale gray back and upperwing with flight feathers darkening towards outer wing

Mississippi Kite has a similar shape, but is much darker in all plumages, never having a white breast, white tail, or the black shoulder or wrist marks of the White-tailed Kite."

Although Tveten opts for calling this a Black-Shouldered Kite, most other sources identify the North American bird a White-Tailed Kite, and I have followed their practice.