The oma’o is generally a solitary bird, but can be found in pairs throughout the year, with pair bonds lasting at least one breeding season (4). The breeding season lasts from January to the end of October (2), with females bearing the responsibility of constructing the nest, and incubating the one or two eggs that are laid (4). The nest is a loose, bulky cup of ferns, moss, leaves and small twigs, sometimes lined with grass, pine needles or flower parts (2). Incubation lasts for about 16 days, and the young remain in the nest for about 19 days before fledging. Both sexes feed the nestlings, and both adults provide parental care for five to six weeks after the young birds leave the nest (4), although they may remain in the natal territory for up to six months (2).
Oma'os are primarily frugivorous, feeding on a wide variety of fruits from understorey shrubs and trees, however it also forages in the forest canopy for invertebrates (2), including earthworms, snails, spiders and insects (3). The oma’o rarely forages on the ground, except for the alpine scrub population, where the diet consists of low-growing berries, and terrestrial invertebrates (2).