Delving into kiwi DNA
Genetic research in the 1980s changed this. It allowed kiwi DNA (deoxyribonucleic acid) to be studied.
DNA contains the genetic instructions used in the development and functioning of all known living organisms. By comparing kiwi DNA, geneticists have been able to infer their evolutionary history.
The genetic research confirmed the great spotted and little spotted kiwi as separate species, but it led to brown kiwi being split up into three distinct species – brown kiwi, rowi and tokoeka. That means today, five kiwi species are formally recognised.
Further genetic research may identify more species and/or subspecies, especially within tokoeka.
The five species
The five formally described kiwi species are:
- little spotted kiwi (A. owenii) on several offshore islands and at Karori Sanctuary in Wellington
- great spotted kiwi/roroa (A. haastii) in the northern South Island
- brown kiwi (Apteryx mantelli) in the North Island
- rowi (A. rowi) at Okarito, on the West Coast of the South Island
- tokoeka (A. australis) in the South Island (Fiordland, the Haast Range and on Stewart and Kapiti Islands).
Different varieties add to the complexity
Two of the five kiwi species have different varieties within them – brown kiwi and tokoeka:
Within brown kiwi, four geographically and genetically distinct forms have been distinguished: Northland, Coromandel, western and eastern.
Tokoeka also have four distinct geographical forms: Haast, northern Fiordland, southern Fiordland, and Stewart Island.
Therefore, kiwi researchers often use the general term ‘taxa’ (singular: taxon) to refer to the 11 different kiwi which are either species or distinct geographical varieties within a species.
Unlike brown kiwi and tokoeka, the little spotted kiwi, great spotted kiwi and rowi species show no clear geographical genetic variations. Little spotted kiwi did use to have a distinct North Island form, but it went extinct in the late 1800s.