Life on the Auckland Islands is hard. Just ask the settlers of Hardwicke who in 1849 were part of the shortest lived British settlement ever – 2 years and 9 months. The Maori only lasted 10 more years themselves. But what about the mammals they brought with them? Upon the islands ‘discovery’ in 1806 pigs were immediately released within a year. Mice and cats were recorded as present by 1820 but in all likelihood had been introduced earlier by secretive sealing camps well before the islands official discovery.
Compared to my National Geographic funded research mission to Antipodes Island two years ago, I can immediately notice the stark difference on the main Auckland Island. Most obvious is the complete absence of procellariiformes (tube-nosed seabirds): albatrosses and petrels. Pigs and cats have hunted out almost every last nest and eaten the egg, chick or sometimes even adult. The chatter of their bird calls is silent. Pigs have also rooted up every edible plant on the island, particularly including the delicious megaherbs. Luckily, nearby Adams Island was saved from this fate, maintaining the crucial seabird-ecosystem link. A short-lived farming attempt on Adams Island also failed in the harsh climate, and in part because the captain was found illegally poaching seals and so lost the lease. Today, all that remains of Hardwicke is a few bricks on the ground, and its cemetery. Ironically Olearia tree daisies, themselves possibly an invader, are now colonising the site.
Grant Harper of BRS and myself tried as hard as we could to detect mice and cats. We tested cat scratch poles scented with catnip and hair tunnel tubes to try and sample cat hair for DNA analysis but with no luck. 650 trapping nights across habitats for mice caught only a handful around the hut where they had retreated. This is in stark contrast to the abundance of mice on nearby Antipodes Island. Interestingly, mice have been present for at least twice as long on Auckland Island, so perhaps the ecosystem has already been completely exploited – the invertebrates we monitored even showed some evidence of recovery. Pigs were so desperate for food they were rooting in boulders on the beach. Overall the environment appears so harsh even the introduced mammals are struggling to survive, which would bode well for any future eradication attempt, as daunting as that might be for an island of 45,000 hectares.
Within the past month I have travelled from the tropics of Fernando de Noronha to subantarctic Auckland Island, and thanks to the support of the NZ Navy on HMNZS Wellington I was able to return from Auckland Island to Auckland, spanning nearly 14 degrees of latitude, in just under 24 hours. It’s about time to sit behind a computer and start to analyse all the information collected this summer and make recommendations for conservation on these world heritage islands.