BRUCE FOSTER

Invasive Species 2011

description / images

It is said that in the 1970s, Raoul Island, once home to the largest concentrations of birdlife in New Zealand, had fallen silent. This once pristine island had finally become victim to the pigs and goats and rats that had originally been set loose by the whalers in the 1800's and, to the exotic plants - many of them fruit trees - brought to the island by Thomas Bell, an early settler. Mysore thorn, Brazilian buttercup, black passionfruit, purple guava, yellow guava, African olive - the list goes on - species that flourished in the subtropical climate. Seeds, spread by birds and the wind soon colonised every corner. The seeds grew, searching for the light, some making it to the forest canopy where they strangled Pohutukawa and other indigenous species, others smothering the undergrowth.

With Raoul on the brink the Department of Conservation stepped in. For more than 30 years staff and volunteers have stalked, hunted, trapped and poisoned the predators and slashed and cut and burned the invasive plants.

Birdlife has now returned to the island. Kakariki and tui are prevelant and petrels are again burrowing into the soft pumice soil and raising chicks. Stepping off the track into the bush on Raoul you see what looks like signs of celebration everywhere. Dotted through the bush are trees wrapped in pink ribbons. It's like a child's birthday party. But as the bush closes around you and it darkens, you remember that this steep volcanic island is treacherous and unpredictable, and you've been given lots of advice about not straying from the tracks, and you start to wonder if the ribbons mark something else – are they signs of warning? Are they saying, 'walk this way and you risk falling off a cliff'?

DOC uses the ribbons to locate sites to be searched repeatedly, year in year out, for the growth of seedlings.The invasive plants may have gone but their legacies of seed banks will live on for decades, perhaps centuries.

For me then, these markers are both celebratory and a warning. They celebrate the restoration of the ecosystem but warn of how fragile these unique places actually are and the threats they face from humans - probably the most invasive species. Once damaged they can't be put back together.

I visited the beach on which Māori hauled their waka for repairs and re provisioning during their long journeys to Aotearoa. Two weeks prior to our arrival at Raoul a tropical cyclone had swept through and ripped all the sand away. Now, in the wake of that cyclone, human-made debris was washing ashore. I photographed what the tides had thrown up. The amount of debris was surprising. If there was this much flotsam on this tiny stretch of ‘pristine’ shoreline, what else was out there drifting about the Pacific?

On a small stretch of beach on Raoul, I found five pieces of rope of various thicknesses, four pieces of fishing net, three bottles, two sandals (both left footed), one section of plastic crate, one empty margarine container, one bottle of Dove moisturiser, and a rat trap – all freshly washed up.

view images