Adult Plumage:
The adult bird has glossy dark brown eyes, ears, and the area behind the eyes. The head, nape, upper neck, and upper back are a glossy fresh mahogany brown. The shoulders, mid-back, and wing coverts are a dark greenish-black with a golden sheen. The lower back and rump are pale sky blue. The primary and secondary flight feathers are greenish-black with edges, tips, and a central stripe of black; the undersides of the feather bases are tinged with brownish-rufous. The tertiary flight feathers are greenish-black, with greenish tips. The tail is tinged with green, the feather shafts are black. The two central tail feathers are elongated into narrow, very pale blue streamers, with blue tips and white shafts in this area. The undersides of the tail feathers are a pale black. The chin and throat are a fresh, pale blue. The breast and belly are a fresh, lettuce green; the lower belly and under-tail coverts are very pale sky blue.
Juvenile Plumage:
The juvenile bird has a dark, dull green head and upper back; the central tail feathers lack the elongated streamers. The throat lacks blue coloration. The mahogany brown coloration on the head and back gradually develops.
Eye Color:
Adults have red eyes; juveniles have brown eyes.
Bill and Legs:
The bill is black. The legs are pale grayish-black or pale brown.
Measurements:
- Wing: 110 – 117 mm
- Lateral tail feathers: 77 – 80 mm
- Central tail feathers: 130 – 167 mm
- Tarsus: 12 – 13 mm
- Bill: 35 – 40 mm
Distribution:
The species is distributed in Thailand, Southern China, Indochina, Malaysia, Java, Sumatra, and Borneo.
Occurrence in Vietnam:
This species has been recorded in Lào Cai, Lai Châu, Hòa Bình, Phú Thọ, Thanh Hóa, Nghệ An, Hà Tĩnh, Quảng Trị, Thừa Thiên, Quảng Nam, Thủ Dầu Một, and Tây Ninh. The birds typically nest on sandy beaches near water.