The long loop track at Aongatete leads gently up into the Kaimai forest. The forest changes as you climb. The lowland trees like puriri and kohekohe give way to tanekaha, totara, miro and the white-flowered tawari.

If you turn west and scramble along bait line 23, you will get a surprise. You will find a lone kauri tree. It is taller than the surrounding forest and must be more than 100 years old.

Aongatete is beyond the southern margin of kauri forest, which stops rather abruptly at Hot Springs Road. Small, planted kauri trees grow in the Aongatete forest around the Outdoor Recreation Lodge but the big, lone kauri, deep in the forest, was not planted. So how did it get there?

It is possible that the seed was brought by a kaka. Kaka prise open kauri cones and eat the seeds. Sometimes they squabble over the best cones and I have seen a kaka on Hauturu, or Little Barrier Island, fly away with a cone clutched in its foot. Perhaps it was looking for a quiet spot to enjoy it. This may be how the seed of the Aongatete kauri was carried long ago, when kaka and kereru flew in great flocks over the forest.

There is another clue in the low forest around the lone kauri. It is dense with rimu and tanekaha and all the trees are of similar height, as if they grew together at the same time. This might have happened when this patch of forest was burned in a lightning strike or a fire lit by Maori. Soon after, a kaka might have dropped the kauri seed into the fertile ash where it would have flourished and, over time, outpaced the slower-growing rimu and tanekaha.

Our climate is warming. Cool-adapted trees like tawari and beech will have to retreat south. Warm-adapted trees like kauri, kohekohe and puriri can follow them to fill the gaps. The forest needs those flocks of kaka and kereru and the other bush birds which used to spread the forest seeds.

But if we want to see flocks of birds in a healthy forest, we must get serious about pest control. At present, beyond the modest area at Aongatete protected by our pest control, rats, possums and stoats are killing the native birds. The scale of the problem is huge. We will need widespread pest control to protect the 37,000 hectares of the Conservation Park and then the native birds will flourish and carry the seeds of the future forest.

Footnote: since this story was written the bait line that runs past the lone kauri has been re-routed, to reduce the risk that volunteers might inadvertently introduce kauri dieback disease to the tree.