 Insects and spiders were taken from decaying wood, from under bark, mosses and lichens, and from the ground. Huia foraged either alone, in pairs, or in small flocks of up to five, which were probably family groups. The sexual dimorphism of the bill structure gave rise to feeding strategies that differed radically between the sexes. The male used its adze-like bill to chisel and rip into the outer layers of decaying wood, while the female probed areas inaccessible to the male, such as the burrows of insect larvae in living wood. The male had well-developed cranial musculature allowing rotten wood to be chiselled and pried apart by "gaping" motions. There are corresponding differences in the structure and musculature of the head and neck between males and females. Huia had very well developed depressor jaw muscles, and an occipital crest that provided extra surface for muscle attachment, allowing the jaw to be opened with considerable force. Once the bird had secured a meal, it flew to a perch with the insect in its feet. The huia stripped its meal of any hard parts, then tossed the remainder up, caught, and swallowed it.
