Male and female Semipalmated Plovers are very similar in appearance, but males tend to have slightly brighter and more extensive black markings on their head and breast, along with more orange on the bill. Females may show duller plumage with more brown feathers on the face and breast band, and their black markings may be less prominent.

Detailed Description:
• Plumage: Both males and females have a brown back and wings, white underparts, and a single black band across the breast. In breeding plumage, they have a black "mask" around the eyes and a black breastband.
• Bill: Both sexes have a short, black-tipped orange bill.
• Legs: They have bright orange legs.
• Female Differences: Females may have browner feathers on their face and breast band, and their black markings may be less distinct.
• Male Differences: Males may have a more prominent black mask and breastband, and their bill may have more orange.

Non-breeding Plumage: In non-breeding plumage, the black markings on both sexes are reduced, with a less distinct mask and breastband, and the bill may be darker. Juvenile Semipalmated Plovers look similar to non-breeding adults, but their wing feathers may have pale buff fringes, giving them a scaly appearance.