Hitching a ride

Our New Zealand biodiversity is bizarre, original, and precious, but it’s constantly changing. Already, many of the species we think of as our own are recent arrivals. The large flightless takaheevolved from a pūkeko-like bird that flew here from Australia. Today’s pūkeko – now found in the main islands of New Zealand and on Raoul Island – is a more recent Australian import. Our parakeets evolved from a parrot from New Caledonia. The silvereye, white-faced heron and welcome swallow, have all arrived in the past two centuries. Most of our dragonflies are Australian. The monarch butterfly is Californian. Almost all of our plants have arrived from somewhere else, through pollen blown on the wind, or seeds carried in the feathers and digestive tracts of birds. The Pacific oysters we harvest and the salmon we catch in our rivers are introduced species.

We need to try to keep out the worst invaders – the aggressive species that could displace native species or destroy our agriculture and aquaculture – but we won’t keep things the same forever.