Adult Plumage (Summer):
- Forehead: White.
- Crown and Nape: Black.
- Upperparts: Dark mahogany brown.
- Outer Tail Feathers: Pale grayish-white.
- Flight Feathers: Outer vanes of feathers are paler at the tips.
- Underparts: White.
Adult Plumage (Winter):
- Crown: With white streaks.
Juvenile:
- Dorsal (Back) Color: Pale brown.
- Ventral (Underbelly) Color: Dirty brown.
- Eyes: Brown.
- Bill and Legs: Black.
Measurements:
- Wing: 278 – 297 mm
- Tail: 145 – 162 mm
- Tarsus (Leg): 23 mm
- Bill: 38 mm
Distribution:
The species is distributed on the islands of the Indian Ocean.
Vietnam:
This species is found on the Paracel Islands (Tây Sa).