Adult Plumage:
Summer Plumage: The head, neck, upper tail, upper wings, and underparts are entirely white. The back, most of the shoulders, axillaries, and secondary wing feathers are bluish-grey. The primary wing feathers are black with white tips.
Winter Plumage: The head and neck are streaked with brown.
Juvenile Plumage:
The juveniles exhibit extensive brown streaking, which persists for a considerable duration. Eye color transitions from white to yellow. The eyelids are red-rimmed. The beak is purplish-yellow, with a red mark on the tip of the lower mandible. Legs are yellow.
Measurements:
- Wing: 415 – 450 mm
- Tail: 158 – 180 mm
- Tarsus (Leg): 62 – 77 mm
- Bill: 49 – 63 mm
Distribution:
This species is distributed in Southern Europe, Northern Africa, and Southeast Asia.
In Vietnam, it is present during the winter months at large river mouths, such as the Red River and Mã River.