Broad-winged Hawk

From below:
 - The wings were a very uniform white except for very dark wing tips and a pronounced dark trailing edge.  There were some very light grayish carpal markings and a grayer area in the secondaries near the dark border.
 - The belly and breast where clean white with some very light streaking laterally near the head.
 - The throat was white bordered by very dark malar stripes which continued into the lateral breast streaks.
 - The tail was light gray with faint bands. The subterminal band was the darkest.

A Red-tailed Hawk would have at least some signs of patagial markings (there was no trace on the bird we saw). It would probably have some belly-band streaking and would probably lack the streaking extending from the prominent malar stripes.  We saw several Red-tailed Hawks in the same area and they seemed to be larger and more bulky with proportionately longer wings.

A Gray Hawk would have more streaking on the breast and belly; less pronounced dark wing tips and trailing edge; and a longer tail.

A Red-shouldered Hawk would have more streaking on the breast and belly and more of a  window in the primaries surrounded by darker areas.  The front part of the upperwing would probably have shown at least some rufous color.

Accipiters would have longer tails with more pronounced bands of more equal widths.  The underwings would have more markings and would lack the dark tips.  They would lack dark malar stripes.