Biodiversity

Considerable bene?ts can be achieved for indigenous biodiversity when invasive vertebrates are removed from islands. In New Zealand, two logistically challenging eradications were undertaken, one to remove cats (Felis catus) and the other Paci?c rats (Rattus exulans) from Te Hauturu-o-Toi/Little Barrier Island (Hauturu). Here we document the short- and long-term impacts of these interventions on the biodiversity of Hauturu. We also assess the extent to which predicted outcomes were re?ected in the measured responses for a wide range of species.

The impacts of house mice (Mus musculus), one of four invasive rodent species in New Zealand, are only clearly revealed on islands and fenced sanctuaries without rats and other invasive predators which suppress mouse populations, influence their behaviour, and confound their impacts. When the sole invasive mammal on islands, mice can reach high densities and influence ecosystems in similar ways to rats.

Following the incursion of rats (Rattus rattus) on Taukihepa (Big South Cape Island; 93.9 km²) off southern New Zealand in 1963, and the subsequent extirpation of several endemic species, the New Zealand Wildlife Service realised that, contrary to general belief at the time, introduced predators do not reach a natural balance with native species and that a safe breeding habitat for an increasing number of ‘at risk’ species was urgently needed.

Rat eradication is a highly effective tool for conserving biodiversity, but one that requires considerable planning eff ort, a high level of precision during implementation and carries no guarantee of success. Overall, rates of success are generally high but lower for tropical islands where most biodiversity is at risk. We completed a qualitative comparative review on four successful and four unsuccessful tropical rat eradication projects to better understand the factors influencing the success of tropical rat eradications and shed light on how the risk of future failures can be minimised.

The Pacific region has benefited from a number of regional and national programmes to both assess the impacts of climate change on biodiversity and develop programmes to adapt to climate change. Such programmes are critical considering that the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) 1/ states that the Pacific region has already experienced temperature increases of as much as 1°C since 1910.

How do introduced species cause problems for biodiversity? What makes a species invasive? When humans introduce non-native species to a new environment, it can have disastrous impacts on native species and the entire ecosystem.

Protected areas (PAs) are a key tool in efforts to safeguard biodiversity against increasing anthropogenic threats. As signatories to the 2011–2020 Strategic Plan for Biodiversity, 196 nations pledged support for expansion in the extent of the global PA estate and the quality of PA management.

n 2010 Parties to the United Nations (UN) Convention on Biological Diversity (CBD) agreed to reduce the rate ofbiodiversity loss within a decade by achieving 20 objectives that are commonly known as the Aichi Targets.