New Zealand Post, 1996 Extinct Birds stamp issue.


The Aptornithidae (Mantell 1848) is an extinct bird family known only from New Zealand. They have been classified into the North Island adzebill (Aptornis otidiformis, Owen 1844) and the South Island adzebill (Aptornis defossor, Owen 1871).

They have traditionally been associated with the rails, in spite of their large size, roughly that of Great Bustard, Otis tarda. However, they have a distinctive jaw like structure which sets them apart from the rails. Affinities with the Kagus have also been postulated. In 1995, Weber & Hesse expressed their suspicion that the Galloanserae may be the sister group to the Aptornithidae, on the basis of cranial characteristics.

Adzebill bones have been found at many sites in the North and South Islands, including Maori kitchen middens. A South Island form, Aptornis oditiformis was larger than the North Island form. The two forms are sometimes treated as different species.

The skull is massive, with a thick walled brain case. The long down curved bill is stout and pointed with thick cutting edges. Small wing bones indicate that adzebills were flightless. They stood about 80 cm tall and may have weighed up to 12 kilograms. With its huge beak, immense neck muscles and strong feet, it seems as if it was superbly adapted for digging, but no one knows the reason for this adaptation. Did it smash open logs searching for grubs and insects, break into the burrows of seabirds and tuatara and eat them, or feed on roots and tubers? Brian Gill has suggested they probably ate berries, leaves of soft herbaceous plants, invertebrates such as insects and spiders, and small vertebrates such as lizards. There is some evidence that they preferred open habitats as opposed to dense forest.

It fell victim to humans, dogs and rats, once the Maori reached New Zealand about 1000 years ago.

adzebill and weka

Memoirs on the Extinct Wingless Birds of New Zealand, 1879. Compares the size of Adzebill (1) to the Weka (2). [Comparison in feet and inches.]

Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Gruiformes
Family: Aptornithidae
Genera: Aptornus
Species: otidiformis, defossor
Sub Species:  
Other common names:  —
Description:  — 

Endemic, Extinct bird

height: 80 cm: weight: up to 12 kilograms.

Where to find:  — 


More Information:  — 
Youtube video  — 
Credit for the photograph: — 
Illustration description: — 

New Zealand Post, 1996 Extinct Birds stamp issue.

Richard Owen, C.B., F.R.S, Memoirs on the Extinct Wingless Birds of New Zealand, 1879.

Reference(s): — 

Gill, Brian and Martinson, Paul, New Zealand’s Extinct Birds, 1991.

Worthy, Trevor H. & Holdaway, Richard N., The Lost World of the Moa, Indiana University Press: Bloomington, (2002), ISBN (0-253-34034-9)

Page date & version: — 

Saturday, 29 July, 2023; ver2023v1