Forest Mimic Copies Call of the Kokako

Forest and Bird, Issue 307, 1 February 2003, Page 8

Forest Mimic Copies Call of the Kokako

ANNE RIMMER

mid the rich medley of A\ on Tiritiri Matangi Island is the soft, three-syllable phrase, ‘kokako; the call which clearly gave this bird its name. Our guide freezes at the sound and turns, excited that her group may see Tiri’s rarest bird. There are only nine adult kokako on this open-sanctuary island near Auckland, and visitors feel privileged to see one. But this group has been fooled, for the soft call is followed by the harsh croaks and whistles of a tui, one of nature’s mimics. The first three North Island kokako arrived on Tiri in 1997, joined by four more the

following year, so it has taken the tui five years to learn this call. Several birds are now so accurate that the volunteer guides are regularly fooled. Tui have always been renowned for their mimicry. In Forest Lore of the Maori ethnologist Elsdon Best wrote that the Maori kept young tui in a cage made of manuka, and taught them to talk. Some birds learned to cry a karakia of welcome several sentences long. In Best’s quaint language: "all say it was necessary to trim or clip the brush-like growth at the end of the bird's tongue ere it could speak distinctly. About five years ago Auckland Zoo had a talking tui, rescued

from a private zoo that closed down. The keepers named it Bonnie Scotland because it spoke in a Scots accent. Another tui at the zoo imitated the call of walkie-talkie radios — so well that keepers reached for their radios. In Forest & Bird magazine for November 1944 (and reprinted in August 1997) a northern correspondent, referring to the late nineteenth century, wrote: ‘When our family settled in the bush country 50 years ago, we always noticed that the tui changed or varied his song every month, about the time of the new moon, and on one occasion for some weeks all the tuis about our homestead would repeat quite correctly seven bars of the latest tune which we youngsters would be whistling. It appears to me that for the last 20 or 30 years the tui has lost the best and loudest of its notes... nearly all he has to say is spoken in an undertone; his once glorious expressions that rang loud and clear throughout the bush in the old days are only muttered today: Captain E. V. Sanderson, Forest and Bird’s founder, mused ‘is the wonderful song of the tui gradually being degraded by the unseemly noises which accompany man’s present existence?’ Or perhaps it was the depletion of other birdsong, as the forest diminished, leaving less for the tui to imitate.

In support of this hypothesis: on Raoul Island, in the Kermadecs, the bush is silent, almost bare of birds, the sad legacy of introduced rats, goats and cats. And on the Kermadecs, observes former wildlife ranger Dick Veitch, the tui do not sing the bell-like notes and whistles we expect. However, they do make the gutteral sounds and clunks which seem to be common to all tuis. John Kendrick, who supplied the bird calls used on National Radio, has accompanied Rhys Buckingham in his search for the South Island kokako. He says southern tui imitate the South Island kokako, a bird now believed extinct. John Kendrick has also made a high-speed recording of tui song and slowed it down to hear the notes normally in the ultra-sonic spectrum — which account for those frustrating moments when the tui is clearly singing its heart out, but we can’t hear a thing! But is something even more tantalizing hidden in that rich tumble of sound? If tui can imitate the kokako so accurately, then other phrases in their repertoire may well have derived from other birds, perhaps even from those longextinct. Is it possible that, buried in the joyous melodies of the tui, we might hear the last echo of the vanished huia?