The response of burrow-nesting petrels and other vulnerable bird species to vertebrate pest management and climate change on sub-Antarctic Macquarie Island

Abstract

Pest species management is causing rapid and signifi cant changes to burrow-nesting petrel populations on sub-Antarctic Macquarie Island. The Weka, Gallirallus australis, was eliminated by 1989 and the Feral Cat, Felis catus, eradicated in 2000. The most abundant burrow nesting petrel species currently, White-headed Petrels, Pterodroma lessonii, Antarctic Prions, Pachypti!.a desolata, and Sooty Shearwaters, Puffinus griseus, have yet to increase in numbers, but are expected to do so in the absence of cats. This study found evidence that Grey Petrels, Procellaria cinerea, began breeding again on the island in 1999, after an absence of over 100 years. Blue Petrels, Halobaena caerulea, and Fairy Prions, Pachyptila turtur, were found to be re-colonising Macquarie Island from offshore stacks after a similar absence. South Georgian Diving-Petrels, Pelecanoides georgicus, were also possibly recolonising the island. Despite the presence of Black Rats, Rattus rattus, most of the bird species discussed are considered capable of population increase. If European Rabbits, Oryctolagus cuniculus, are not elimi nated or maintained in reduced numbers, some petrel populations will never fully recover. Climate change could have a negative impact on burrow-nesting petrels, and is likely to exacerbate the detrimental effects of the remaining pest species on vulnerable indigenous bird species, compounding the need for remedial action against rabbits in particular. Together with predictions that other petrel species will now return to breed, certain terrestrial bird species, alien to the region, may invade Macquarie Island as a consequence of the combination of pest eradication and changing climatic conditions.

The avifauna of Bishop and Clerk islets and its relationship to nearby Macquarie Island

“…Breeding by this species on Bishop Islet is added confirmation that rats do not exist here despite perhaps having had at least one opportunity from shipwreck to do so (Cumpston 1968). Regardless, evidence from other islets adjacent to Macquarie Island suggests that even if rats did come ashore at any time on Bishop Islet they could not survive long-term under the environmental conditions here (Brothers & Bone 2008).…”

“…1herefore the numbers observed on Bishop Islet do not necessarily indicate that more than one pair may breed. 'nle total population for the Macquarie Island region is 127 breeding pairs (Brothers & Bone 2008).…”

Notes on rare, vagrant and exotic avifauna at Macquarie Island, 1901-2000

“…The influence on the dispersal of birds of the extreme winds that can occur in the region has been discussed in several papers (Williams 1953, Merilees 1971b, Adamson et al 1988, Bridgman & Maddock 1994, Brothers & Bone 2008. This is well-illustrated with the racing pigeon (Rock Dove above) which was released in Victoria, Australia, on the morning of 29 October 1989 in a race to northern Tasmania.…”

“…The breeding species recorded here consist of seven seabirds, three exotics and one introduced species. The seven breeding seabird species are known to, or likely to, have bred previously on the main island and four appear to be re-establishing there, as control and eradication programs for introduced species, started in the late 1970s, take effect (Brothers & Copson 1988, Copson 2004, Brothers & Bone 2008.…”

Change in the distribution of the indigenous grass Poa litorosa on sub-Antarctic Macquarie Island following the eradication of rabbits

“…One predicted outcome of the release of grazing pressure by rabbits is the expansion of some species and the reduction of others (Copson & Whinam 2001). A lack of historical data from the period prior to rabbit establishment (Whinam et al 2014) together with ongoing climate change (Brothers & Bone 2008, Adams 2009) make predictions about a new postgrazing equilibrium state of the vegetation uncertain. It is therefore essential to establish baseline data now, at the start of this new phase for Macquarie Island.…”