The nīkau is New Zealand's only native palm – or so we thought. There was once another palm. A giant. A true palm of the tropics, growing tall and straight in the warm forests of the North Island. Its trunk was thick enough to hollow out, its leaves were broad and fan-shaped, its fruit were large and fleshy. It was a sentinel of the ancient forest, a tree that fed the birds and sheltered the
kākāpō. And then it vanished.
Size and its role in the forest made it special. A 20-metre palm is a spectacular tree – a single straight trunk, a crown of leaves at the very top, a silhouette that stands out against the sky. Its fruit were large and nutritious – a feast for the
kererū, the
kākā, and the
kākāpō. Its leaves provided thatch and shelter. Its trunk – and here is the most important part – often developed natural hollows as it aged. Hollows large enough for a kākāpō to nest in.
It was the apartment block of the forest. The
kākāpō – the giant, flightless, nocturnal parrot – nested in hollows in the ground and in trees. The giant palm offered something special: a hollow trunk, safe from ground predators, high above the forest floor. A kākāpō could climb the rough bark, enter the hollow, and raise its chicks in safety. The palm also provided fruit for the
kererū, which dispersed its seeds across the forest. It was a keystone species, a tree that made the whole ecosystem work.
It was a slow-growing palm, taking decades to reach maturity. It produced large fruit that required a bird – probably the
kererū or the
kākā – to swallow and disperse. That partnership worked when the birds were abundant. It failed when the birds declined.
Rats, deforestation, and the extinction of its partners destroyed it. The kiore (Pacific rat) arrived with Polynesian settlers. Rats climb. Rats eat fruit. Rats eat seeds. They ate the palm's fruit before the birds could disperse them. They ate the seedlings. They raided the hollows, eating the eggs and chicks of the
kākāpō that nested there. At the same time, Polynesian settlers cleared the lowland forests for cultivation. The giant palm, which needed mature forest with space to grow tall, could not survive in open land. Its seedlings were trampled. Its old trees were felled for timber or burned.
And then the
kākāpō declined. The giant parrot, driven by hunting and rat predation, retreated from the lowlands. Without the kākāpō to nest in its hollows – and without the
kererū to disperse its seeds – the palm lost its partners. It was a cascade of extinction: the bird lost the tree, the tree lost the bird, and both faded away.
By the time Europeans arrived, the giant palm was gone. The
kākāpō survived – barely – on a few offshore islands. But the tree that once sheltered it, the giant palm of the lowland forest, had vanished without a trace.
The forest sentinel is a ghost because it was always sentinel-like – standing tall above the canopy, a landmark for birds and travellers. Now there is nothing to see. The lowland forests are still there – some of them – but they are quieter, emptier, palm-less.
We brought the rats. We cut the forest. Then we wondered why the
kākāpō had nowhere left to nest.