Wallace's fairywren is a small species of fairywren, 11–12.5 cm (4.3–4.9 in) in length and weighing 7–8 g (0.25–0.28 oz). Adult males have a black crown and nape with blue feather tips and a black face with an incomplete white eye-ring and white ear-tufts. The scapulars and back are rusty brown, with brownish-grey upperwings, white underparts, and brown tails. The black beak is long, broad, straight, and bluntly pointed, with a white tip. The iris is red-brown, with short, flesh-brown legs. Females are similar to males, but have a pale yellowish wash to the throat and a duller crown. Subspecies coronatus has a creamy wash to the underparts. Immatures are duller than the adults, with shorter bills and ear-coverts, along with having the crown be speckled buff instead of blue.
Little is known about its vocalisations, but hissing see see see see calls are given by foraging parties.
Wallace's fairywren is endemic to New Guinea. It is common throughout New Guinea, except on the Huon Peninsula, eastern Sepik-Ramu, and most of the northern parts of the southeastern peninsula. The species inhabits foothill rainforest and secondary growth between elevations of 100–800 m (330–2,620 ft), although they can be found up to elevations of 1,200 m (3,900 ft) and in lowland plains where there is suitable vegetation.
It is typically found more in trees than in the undergrowth, most commonly from 2–10 m (6.6–32.8 ft) above the ground, but can be found from ground level to 40 m (130 ft) in the canopy. They most commonly inhabit trees with tangles of vines and climbing bamboo at forest edges.
Wallace's fairywrens are thought to be mainly insectivorous, feeding on insects and spiders. They forage by gleaning and probing in forest tangles and thickets. It has been known to forage with mixed species flocks, typically in family groups of 4-8 individuals.
Breeding occurs throughout the year, with a peak in September-December. Out of three observed nests, two were attended by three adults each. Nests are domed structures, with a hooded side entrance near the top, and are made out of fine grass, cobwebs, and strips of palm frond, lined with finer fibres and sometimes covered with bits of moss and epiphytes. Nests are placed in vines at a height of 5–10 m (16–33 ft) above the ground, although one nest was built in a 1–5 m (3.3–16.4 ft) tall shrub at the top of a 30 m (98 ft) tall cliff face. Eggs are thought to be laid in clutches of two. Chicks are fed by both parents once they hatch.
Wallace's fairywren is listed as least concern by the IUCN due to its large range and lack of significant population declines. They are common throughout foothill rainforest in their range. However, large-scale clearing of rainforest may be a potential threat.
