The haunting song of the kokako is familiar to most New Zealanders, although they may not realize it. Kokako songs are regularly used in radio and television advertisements to represent the sound of a healthy forest. It's an appropriate symbol: because kokako can only survive in relatively intact, pest-free areas of native bush, their presence is an indicator of a healthy ecosystem. (Scroll down for links to more kokako songs.)

Aside from their beauty, kokako songs are remarkable for the way they're usually performed: the male and female of a pair combine their voices. Most of what we know about bird song comes from studies of northern temperate species, where males do most if not all of the singing. So when we hear birds singing, we automatically assume that we're listening to males. However in many species (particularly in the tropics), both males and females contribute to the song as kokako do, a behaviour called duetting (1, 2). Why do so many birds sing as duetters rather than as soloists?

A current research program focuses on this question, with the kokako as its study subject In addition to working out the basic structure and variation in kokako song, the project is looking at three potential functions of duetting: mate guarding, pair-bond maintenance, and territorial defense. The study combines analysis of natural, spontaneous singing and playback experiments. Some of the questions being asked are:

Does the precision or variability of duet performance depend on how long a pair has been together?
Does duetting allow birds to direct aggression towards opponents of the same sex?
Does response to playback depend on whether song comes from one or two spatial sources, voices, or sexes?
Does the rate of response to a mate's singing depend on factors such as time of year?

As with many species, kokako also have dialects, or regional differences in their songs. Although they are always recognizable as kokako, birds from different populations can sound quite distinctive. As the song project unfolds, it will expand to include the effects of dialect on pairing and territorial behaviour- an important issue, as translocations and captive breeding often require adults from different populations to interact. Understanding how duets and dialects work in kokako may enhance the success of these important conservation efforts.

This song (212 kb mp3) was recorded from a pair whose song is somewhat different from the pair linked at the top of the page.

On this recording (236 kb mp3) you can hear the recordist (Brice Ebert) separating the two voices.

In addition to the full song, kokako sing a number of shorter phrases. The mew (20 kb mp3) is common in many populations. Other sounds include tooks (16 kb mp3), tones and soft notes (32 kb mp3)


The song project is funded by a National Science Foundation International Research Fellowship to Dr. Laura Molles. Dr. Molles is based at Lincoln University in Canterbury, New Zealand and works in close collaboration with Dr. Joe Waas (University of Waikato, Hamilton , New Zealand) and Jeff Hudson.

Except where noted all songs on this site were recorded by Laura Molles.

Photos on this page by Guy Vickers.

References:
(1) Farabaugh, S. M. 1982. "The ecological and social significance of duetting." Acoustic Communication in Birds. D. E. Kroodsma, E. H. Miller and H. Ouellet, eds. New York, Academic Press: 85-124.
(2) Morton, E. S. 1996. "A Comparison of Vocal Behavior among Tropical and Temperate Passerine Birds." Ecology and Evolution of Acoustic Communication in Birds. D. E. Kroodsma and E. H. Miller, eds. Ithaca, Cornell University Press: 258-268.