before stalling and dropping into a powered dive, then repeating. Much of this behaviour is more notable during the breeding season of early spring—September and October. Females alone build nests of twigs, grasses and mosses. Feeding Nectar is the normal diet but fruit and insects are frequently eaten, and pollen and seeds more occasionally. Particularly popular is the New Zealand flax, whose nectar sometimes ferments, resulting in the tūī flying in a fashion that suggests that they might be drunk. They are the main pollinators of flax, kōwhai, kaka beak and some other plants. Note that the flowers of the three plants mentioned are similar in shape to the tūī's beak—a vivid example of mutualistic coevolution. Songs and calls Tūī are known for their noisy, unusual, sometimes soulful calls, different for each individual, that combine bellbird-like notes with clicks, cackles, timber-like creaks and groans, and wheezing sounds. Tūī have a complex variety of songs and calls, much like parrots. They also resemble parrots in their ability to clearly imitate human speech, and were trained by Māori to replicate complex speech. They also re-create sounds like glass shattering, car alarms, classical music and advertising jingles. All birds have a sound producing organ called a syrinx, which is typically controlled with two sets of muscles. Songbirds or passerines like tūī have nine pairs of muscles giving them the ability to produce much more complex vocalisations, and they can be seen to be very physically involved with their songs. Their dual voice box allow tūī to make two sounds at the same time. Tūī song also exhibits geographical, microgeographic, seasonal, sex and individual variation. Some of the wide range of tūī sounds are beyond the human register. Watching a tūī sing, one can observe gaps in audible sound when the beak is agape and throat tufts throbbing. Hill (2011) describes these apparent gaps in the song, but notes that the audio recording equipment used in the research was not capable of detecting ultrasound above a frequency of 22.1kHz. Tūī will also sing at night, especially around the full moon period. Gallery References External links Prosthemaderas Novæ Zealandiæ — (Tui or Parson Bird) From A History of the Birds of New Zealand by Walter Buller Tui – New Zealand native land birds Department of Conservation Kiwi Wildlife tours Sound gallery (MP3 link) Comparison can be made with the bellbird song through this page. Talking