Adult males are so wildly colorful that the only real problem is singling out a field mark. The dark forked tail separated from the dark belly by white undertail coverts creates a pattern that is another excellent point of separation from most other U.S. hummers. Adult male Broad-billed Hummingbird.
Females are another matter altogether.
In practice, though, female broad-billeds are actually fairly easily identified by the combination of grayish ear patches, often set off from the green of the crown by a white eyeline. Female broad-billed hummer. Note gray ear patches bordered above by a thin white eye-line. Another good field mark is the bi-colored bill, although sometimes the orange tones are limited to the underside of the bill. The same female broad-billed hummer as above, with head turned.