The grey warbler (Gerygone igata), also known by its Māori name riroriro or outside New Zealand as the grey gerygone, is an insectivorous bird in the family Acanthizidae endemic to New Zealand. It is sometimes known as the rainbird. Its natural habitat is forests, but also tends to occupy lower vegetation habitats. These insectivorous birds feed on insects living in shrubs, and often feed on the wing. They are found throughout New Zealand, as well as offshore islands where shrub exists. They also flourish in suburban areas where there is vegetation present.

The grey warbler has a long tail that is darker than its grey-brown body, with white tail end markings as well as a white tail underside. There is little sexual dimorphism between males and females, aside from females usually being smaller than males. Warblers are especially small; weighing around 6.5g with an average length of only around 10cm. Adults have a signature ruby red eye, while juveniles have a brown eye, as well as yellowish feathers around the face and underbody. Its nest is especially unique among birds, with a pear shaped, dome like hanging nest that has a circular side entrance hole.

The male's song often starts with a series of three squeaks and builds into a distinctive long plaintive wavering trill that rises and falls. Only the male warblers sing year-round, to attract mates and defend territory. Male songs are particularly loud during summer and spring, which lines up with the warblers breeding season. The warbler's song is a pleasant, soft warble and varies between different populations. In fact, studies looking at temporal aspects of warbler song found that the song shifted to a higher frequency over a period of 7 years. It was hypothesised that this was due to the reintroduction of native species to the warbler's habitat. The purpose of the song is not only to attract a mate, but also to ward off potential threats that enter a warbler's territory, whether that be predators or other warblers.