[5][7] Previously widespread, kōkako populations throughout New Zealand have been decimated by the predations of mammalian invasive species such as possums, stoats, cats and rats, and their range has contracted significantly.

[10][11] The genus name is derived from the Ancient Greek word kallaia for a cock's wattles.

[7] New Zealand wattlebirds have no close relatives apart from the stitchbird, and their taxonomic relationships to other birds remain to be determined.

[6][7][14] The South Island kōkako, Callaeas cinereus, by contrast has largely orange wattles, with only a small patch of blue at the base.

[15] Its diet consists of leaves, fern fronds, flowers, fruit and invertebrates.