What plumage feature reliably distinguishes an adult male Yellow-bellied Sapsucker from a female?

The male has a bright red crown and a bold black bib beneath a white throat.

While the namesake yellow belly is often subtle, identification is usually more reliable based on other field marks, especially comparing adult males and females. Adult males are characterized by a striking appearance: a glossy black back speckled with white, complemented by a bold black bib directly beneath a clean white throat. Crucially, the male sports a bright red crown (top of the head) and often a matching red throat patch, creating a distinct cap and bib combination. Females are similar but typically exhibit less vibrant coloring, often featuring a paler crown—sometimes white or off-white instead of solid red—and may also lack the extensive red coloration on the throat patch.