New Zealand was once home to a diverse array of flightless birds before the arrival of humans. Many of these unique species were driven to extinction shortly after Polynesians first settled New Zealand around 750-1300 AD. Europeans later exacerbated the loss of flightless birds during colonization of the islands in the 18th and 19th centuries.
Moa
The moa were large flightless birds native to New Zealand. There were 9 species of moa belonging to 6 genera. Moa were ratite birds related to emus, ostriches, rheas and kiwis. They ranged from the size of a turkey to larger than an ostrich. Most species went extinct by 1500 AD, with the last few species surviving on islands in the South Island until the late 18th century.
Here are some key facts about the moa:
- Largest moa (Dinornis robustus) could reach nearly 12 feet (3.6 m) tall and weigh over 500 lbs (230 kg)
- Smallest moa (Pachyornis elephantopus) was around the size of a turkey
- Herbivores that fed on shrubs, trees, herbs and some mosses and ferns
- Important part of traditional Māori diet and culture
- Hunted and habitat loss led to extinction
- 9 species classified into 6 genera:
- Anomalopteryx
- Dinornis
- Emeus
- Euryapteryx
- Pachyornis
- Megalapteryx
Largest Moa Species
The largest moa belonged to the genus Dinornis. There were three species of giant moa in this genus:
- North Island Giant Moa (Dinornis novaezealandiae) – Up to 12 feet tall and 550 lbs
- South Island Giant Moa (Dinornis robustus) – Tall as 12 feet and 500 lbs
- Stout-legged Moa (Dinornis struthoides) – Over 6 feet tall and nearly 400 lbs
Smallest Moa Species
The smallest moa belonged to the genus Pachyornis. There were three diminutive species:
- Heavy-footed Moa (Pachyornis elephantopus) – Around 20 inches tall and 25 lbs
- Crested Moa (Pachyornis australis) – Up to 3 feet tall and 70 lbs
- Mappin’s Moa (Pachyornis mappini) – Average height around 2 feet tall
Other Extinct Flightless Birds
In addition to the moa, several other now extinct flightless bird species once inhabited New Zealand before the arrival of humans and mammals.
Adzebills
The adzebills (family Aptornithidae) were two species of flightless birds related to the rails. They had massive head and beaks that likely helped them pry apart rotting wood to find insects and worms.
- North Island Adzebill (Aptornis otidiformis) – Hunted to extinction by 1500 AD
- South Island Adzebill (Aptornis defossor) – Survived until around the 1840s
New Zealand Geese
New Zealand was once home to three species of large extinct geese before introduction of rats decimated their numbers:
- South Island Goose (Cnemiornis calcitrans) – Largest goose at 22 lbs
- North Island Goose (Cnemiornis gracilis) – Went extinct 1300 AD
- Scarlett’s Duck (Malacorhynchus scarletti) – Survived until early 19th century
Other Extinct Birds
Some other extinct flightless birds of New Zealand include:
- Snipe-rail (Capellirallus karamu) – Flightless rail, went extinct 1500 AD
- Dieffenbach’s Rail (Gallirallus dieffenbachii) – Flightless rail, extinct mid-19th century
- Hakawai (Coenocorypha barrierensis) – Large flightless wren, extinct 1870s
- New Zealand Quail (Coturnix novaezelandiae) – Extinct 1875
- Hodgen’s Waterhen (Gallinula hodgeni) – Extinct late 19th century
Reasons for Extinction
There were several reasons why so many flightless birds in New Zealand went extinct following human arrival:
- Hunting – Maori hunted moa and other large flightless birds as food sources
- Habitat Loss – Forest clearing and fire changed landscapes
- Predators – Rats, dogs and other mammals preyed on birds and eggs
- Competition – Competition from introduced species
The moa and other flightless birds had evolved for millions of years without any mammalian predators. They were ill-equipped to deal with hunting pressure and the introduction of predators like rats that ate eggs. Their habitats also suffered dramatic changes as early human settlers burned and cleared forests for agriculture.
Flightlessness in New Zealand Birds
Many birds evolved flightlessness in New Zealand for several reasons:
- No native mammalian predators
- Plentiful food sources on land and little need to fly between islands
- High metabolic cost of flying for large birds
In the absence of predators, flight became less essential for survival for many species. Flight is very energetically expensive, especially for larger birds. Losing the ability to fly helped enable many species like the moa to grow much larger than flying ancestors.
Surviving Flightless Birds
The kiwi are the only surviving flightless birds remaining in New Zealand today. All other native flightless species went extinct. The five species of kiwi are all threatened and at risk of extinction.
Here are the five living species of kiwi:
| Species | Conservation Status |
|---|---|
| North Island Brown Kiwi (Apteryx mantelli) | Endangered |
| Okarito Kiwi (Apteryx rowi) | Critically Endangered |
| Little Spotted Kiwi (Apteryx owenii) | Endangered |
| Great Spotted Kiwi (Apteryx haastii) | Vulnerable |
| Southern Brown Kiwi (Apteryx australis) | Vulnerable |
Intensive conservation efforts for kiwi include predator control, captive breeding, and population management. Ongoing efforts to save the remaining flightless kiwi from extinction continue today.
Conclusion
New Zealand was once the domain of a myriad of fascinating and unique flightless birds found nowhere else on earth. Unfortunately, many were driven extinct shortly after the arrival of humans and the mammals they brought with them. Overhunting and habitat loss doomed giant moa and other defenseless flightless species not adapted to these new threats. Only the persisting kiwi remains today to represent New Zealand’s legacy as a refuge for birds that lost the ability to fly.
