Blink and you may miss the titipounamu – New Zealand’s smallest endemic songbird.

Titipounamu flit about the foothills of the Tararua Ranges and in good numbers at Pūkaha Mount Bruce, their squeaks barely audible. Only on the best days do they become visible – generally when scurrying about in branches searching for small invertebrates among the mosses and lichens.

The titipounamu, also known as the North Island rifleman (Acanthisitta granti), is one of the few surviving New Zealand birds whose history stretches back to when the earliest warblers graced the forest with their calls. There were once six native wren species spread across both islands, whose relatives made their presence known as early as 85 million years ago in Eastern Gondwana, eventually sharing the forest with fellow ancient critters such as the wattlebird and New Zealand thrush.

Sadly, being small and flightless wasn’t a great asset when mammals arrived on the coattails of European settlers and began to impose a new predatory order on the birdlife. Two of the New Zealand wrens became infamous for their manner of extinction: the Lyall’s wrens on Takapourewa (Stephens Island) were all brought home to the lighthouse keeper’s house by the pet cat while, on Big South Cape Island in the 1960s, the bush wren population was wiped out by an invasion of rats, under the noses of Wildlife Service rangers. Only the titipounamu (and its South Island counterpart, the subspecies Acanthisitta chloris) and the New Zealand rock wren (pīwauwau) have lived to see modern times.

At a mere 6 grams and 8 centimetres long, the titipounamu is barely an appetiser for a passing rat, and

can fit into the tiniest of crevices – this may have aided its survival. Males are slightly smaller than females, though both have similarly diminutive features: short, rounded wings, a stumpy tail and a fine bill, handy for extracting insects from bark.

It has a fetching colour scheme – males are a vivid green, while females are flecked with brown and lemon. Its English name, rifleman, is believed to be inspired by their plumage, as the colour scheme is similar to a British soldier’s uniform. However, other bird fanciers say it was so named as it follows a spiralling route with its beak when going over bark for food – to ‘rifle’ means to make spiral grooves, as are found in a gun barrel.

Like their ancestors, titipounamu are poor fliers, preferring instead to scale tree trunks for a meal, gripping on with their oversized toes (oversized in proportion to the rest of it, that is). They are hyperactive characters, regularly flicking their wings and making constant calls to one another while foraging. Unfortunately, these chirps are pitched too high for most humans’ hearing.

Titipounamu were once widespread throughout the country, but numbers have decreased, thanks to clearing of forest and bush. Poignantly, due to their being able to fit into small spaces, bird watchers have noticed titipounamu remaining inside a tree trunk long after it’s been felled.

A small, green bird that can barely squeak may not be, on the face of it, that exciting – until it is put into its historical perspective. The Tararua Ranges are among the youngest in the country, barely a couple of million years old. The titipounamu, on the other hand, is nearly as ancient and certainly as precious as its namesake rock. Literally older than the hills.

Story by Erin Kavanagh-Hall and Tony Silbery