By Guest Author 07/04/2022

Professor Kevin Burns, Te Herenga Waka — Victoria University of Wellington

Most of us know the sad story of New Zealand’s natural history. Having evolved for millennia in the absence of mammals, most New Zealand animals never learned how to cope with the throngs of predatory mammals that accompanied us on our journey to Aotearoa New Zealand.

Thankfully, recent conservation efforts have stemmed the tide of extinction. Fenced sanctuaries like Zealandia now support vibrant populations of native birds, safe from harm from introduced rats, cats and stoats.

Given the rarity of native birds and their conservation needs, for the past five decades research on New Zealand’s flora and fauna has focused on wildlife management. Yet restored populations of New Zealand’s native birds in places like Zealandia are proving to be an untapped scientific resource. The same fearlessness that almost led to the demise of the New Zealand avifauna also provides a unique window into general principles of animal behaviour and evolution.

I make the short trip from my desk at the Kelburn Campus to Zealandia weekly to observe native birds—not only to help management efforts, but also to better document unique and undiscovered features of New Zealand’s avifauna. I’m often amazed at what I stumble into.

On a dark and dreary afternoon last year, I observed something truly remarkable. As I walked down a forest trail, I noticed a New Zealand falcon perched on a tree branch in the forest understory. After a minute or so, it flew away and landed in a new location, where it disturbed a group of kākā. Suddenly faced with a deadly native predator, the flock of kākā immediately became highly agitated and began to vocalise loudly.

Then a female kākā did something extraordinary.

It flew towards the falcon and landed on a branch above its perch. The kākā then began digging at a rotten section of the adjacent tree trunk. After several seconds of chiselling, it removed a solid, golf ball sized piece of wood. It then carried the chunk of wood in its mouth along the branch above where the falcon was perched. Once immediately above the falcon, it raised its head upwards, and in a single downward motion with its head, released the piece of wood towards the falcon below. The piece of wood stuck the falcon in the back, causing it to immediately take flight and disappear from view.

This seemingly innocuous observation demonstrates something remarkable. The kākā manufactured a wooden projectile, which it then transported to a new location where it used the projectile to deter a predator from a distance.

Tool use was once thought to be a strictly human behaviour, and some of the most sophisticated tools manufactured by humans are weapons. However, anti-predatory tool use is fleetingly rare in the animal kingdom, making the behaviour of the kākā in Zealandia truly exceptional.

This behaviour is not without precedent for kākā, either. Wildlife managers at Zealandia colour band all the chicks born in the sanctuary each year, and when they have taken kākā chicks from the nest to band them, kākā parents have dropped twigs and pinecones onto the managers. Dropping woody materials onto animals perceived as predators could therefore be a common behaviour for these native birds.

How many other exceptional behaviours are waiting to be discovered by curious naturalists in Zealandia? Thanks to ongoing conservation efforts by wildlife managers, it’s not hard to believe that the New Zealand avifauna has much to teach us about general principles of ecology and evolution.

KC Burns is a Professor of Biology at Te Herenga Waka—Victoria University of Wellington. He is field biologist who is interested in a wide range of topics involving the ecology and evolution of plants and animals. Rather than focus on a single type of organism, study site, methodology or hypothesis, his research directions result spontaneously from field observations.