Vietnamese crested argus

The Vietnamese crested argus (Rheinardia ocellata) is a large and spectacular peafowl-like species of bird in the pheasant family with dark-brown-spotted black and buff plumage, a heavy pink bill, brown irises and blue skin around the eyes. The head has two crests; the hind crest, which extends down the occiput, is erected when alarmed and during intentional behaviors including pair bonding and courtship displays. The male has a broad and greatly elongated tail of twelve feathers. The tail covert (or "train") of the male is the longest of any bird and is believed to contain the longest (and widest) feathers to occur in a wild bird; the Reeves's pheasant has tail feathers of similar length but which are considerably narrower. The tail coverts measure up to 1.73 m (5.7 ft) in length, giving the bird a total length of 1.9–2.39 m (6.2–7.8 ft).

Both sexes are similar in size, with females possessing a prominent marbled barring and more colourful dorsal plumage than the male. They possess white facial plumage marked with disruptive patterning. The female's crest is different morphologically, with more rigid plumes that take up more surface area along the occiput and upper hind neck. Their tails are elongated and laterally compressed, although females have considerably shorter tails. The average length of the female is 74–75 cm (2.43–2.46 ft). Despite being sexually dimorphic by length, the male only weighs about 20% more than the female. The average weight is around 1.5 kg (3.3 lb).

The wings of the Vietnamese crested argus are of unusual size and length for its weight. They are wide and square like those of Argusianus instead of rounded and abbreviated like those of 'true' pheasants. Additionally, there is no discernible trailing edge secondary wing notch amongst the flight feathers, indicating a capacity of sustained flight in species of this genus. Their wings are morphologically similar to the wings of certain semi-arboreal Craciformes, particularly the genus Pipile. The feet and legs of crested argus are also notable in the presence of curiously developed leg scales in males which are widened in such a matter that they give each limb the appearance of the foreleg of a varanid lizard. The toes are long and gracile and like other peafowls, while the hind toe is less recumbent than those of more strictly terrestrial Galliformes.