Kōkako (Callaeas) are two species of endangered forest birds which are endemic to New Zealand, the North Island kōkako (Callaeas wilsoni) and the presumably extinct South Island kōkako (Callaeas cinereus). They are both slate-grey with wattles and have black masks. They belong to a genus containing five known species of New Zealand wattlebird, the other three being two species of tieke (saddleback) and the extinct huia. 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. In the past this bird was called the New Zealand crow; however, it is not a crow at all, but it looks like one from a distance. The spelling kokako (without a macron) is common in New Zealand English. Taxonomy The kōkako appears to be a remnant of an early expansion of passerines in New Zealand and is one of five species of New Zealand wattlebirds of the family Callaeidae, the others being two species of endangered tieke, or saddleback, and the extinct huia. New Zealand wattlebirds have no close relatives apart from the stitchbird, and their taxonomic relationships to other birds remain to be determined. Description The North Island kōkako, Callaeas wilsoni has blue wattles (although this colour develops with age: in the young of this bird they are actually coloured a light pink). The South Island kōkako, Callaeas cinereus, by contrast has largely orange wattles, with only a small patch of blue at the base. Behaviour The kōkako has a beautiful, clear, organ-like song. Its call can carry for kilometres. Breeding pairs sing together in a bell-like duet for up to an hour in the early morning. Different populations in different parts of the North Island (if any populations of the South Island kōkako remain they are at present unknown) have distinctly different songs. The kōkako is a poor flier and seldom flies more than 100 metres. The wings of this species are relatively short and rounded. It prefers to hop and leap from branch to branch on its powerful grey legs. It does not fly so much as glide and when seen exhibiting this behaviour they will generally scramble up tall trees (frequently New Zealand podocarps such as rimu and matai) before gliding to others nearby. Its ecological niche has been compared to that of a flying squirrel. Its diet consists