Red-necked phalaropes exhibit reversed sexual dimorphism, meaning females are more brightly colored than males during the breeding season. Females have a striking appearance with a bright reddish-brown neck, white throat, and gray upperparts, including brown-streaked backs. Males, while similar, are duller in coloration, with a more muted brown head and neck and less vibrant reddish-brown on their neck. In their non-breeding plumage, both sexes appear similar, being gray above and white below, with a white face and dark ear patch.

Breeding Plumage:
• Female: Dominant, brightly colored with a reddish-brown neck, white throat, and gray upperparts. She also has a white cheek patch.
• Male: Duller coloration with a brown head and neck and less vibrant reddish-brown on the neck. He may also have a small white spot above the eye.

Non-breeding Plumage:
• Both sexes are gray above and white below, with a white face and a dark ear patch.
• The Red-necked Phalarope's back is streaked gray, while the Red Phalarope's back is unstreaked.
• Juveniles have a buff and black-streaked plumage.

Key Differences:
• Coloration: Females are noticeably brighter and more colorful than males during the breeding season.
• Sex Roles: Phalaropes reverse traditional sex roles, with females being more dominant and males incubating the eggs and raising the young.
• Bill: Both sexes have a thin, needle-like bill.
• Size: Females are generally larger than males.