The grey warbler is known as the riroriro in Māori. This ubiquitous little bird is well known in Māori legends and whakataukī (proverbs). The saying: “I whea koe i te tangihanga o te riroriro?” can be translated as: “Where were you when the riroriro appeared?”—meaning, you should have been here in spring at planting time.
Its song is a plaintive and lilting warble or trill and once you are familiar with it you will hear it throughout the country.
This little bird feeds on the wing, hovering around the tips of foliage to glean small invertebrates from the vegetation. While it needs an environment with trees, scrubby second-growth pine forest, orchards and suburban gardens all seem to provide a suitable habitat.
Like most forest species, you will usually hear this bird before you see it. However, the grey warbler is easy to spot with its aerial manoeuvres, distinctively fanned tail, and white-tipped feathers.
The abundance of grey warblers does not seem to be affected much by predators, though the species is a little more obvious on predator-free islands than on the mainland. This may be, in part, due to their pendulous, domed nest hanging at the extremities of some dense vegetation.
Grey warblers are also able to withstand being the only mainland host for the brood parasitic shining cuckoo. The female shining cuckoo removes a single egg from the grey warbler's clutch, replacing it with her egg. When the cuckoo chick hatches it ejects all the warbler eggs and chicks and monopolises the efforts of the surrogate warbler parents until it fledges.