Introduction

Globally the introduction and spread of invasive species is a leading cause of biodiversity loss. Invasive species are particularly destructive to island species and ecosystems. Nearly two-thirds of recent extinctions (Jones et al. 2016) and 75% of all recorded terrestrial vertebrate extinctions occurred on islands and most were caused fully or in part by invasive species (McCreless et al. 2016). Currently, 40% of species threatened with global extinction are from island. Eradication of invasive mammals has recently been modelled as having the potential to prevent up to 75% of extinctions of threatened species on islands (ibid).  

Exotic rodents, particularly ship rats and perhaps mice, have been a key (and often the critical) cause of extinction, extirpation (local population loss) and decline of many native species, adverse changes to island ecosystems, as well as economic damage to island peoples’ livelihoods and potentially to their health (DEWHA, 2009). Ship rats alone are responsible for the severe decline or extinction of at least 60 vertebrate species (Towns et al. 2006), and currently endanger more than 70 species of seabird worldwide (Jones et al. 2008). They suppress plants and are associated with the declines or extinctions of flightless invertebrates, ground-dwelling reptiles, land birds and burrowing seabirds (Towns et al. 2006). Mice have also been shown to impact on plants, invertebrates and birds (Angel et al. 2009).  

On LHI, rodents are implicated in the extinction of at least five endemic birds and at least 13 invertebrates (DEWHA, 2009). They are also recognised in the LHI Biodiversity Management Plan (DECC, 2007) as a threat to at least 13 other bird species, 2 reptiles, 51 plant species, 12 vegetation communities and numerous threatened invertebrates on the island (ibid) including the listed threatened species in the table below.

Lord Howe Island Biodiversity Management Plan 2007

Listed Species Currently Impacted by Rodents on the LHIG