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Cats and Rats Lead Extinction Sweepstakes

As we travelled around the globe humans transported our favourite mammals with us. Either inadvertently such as rats, or intentionally such as cats. These species introductions have gone on to have unrivalled impacts. A paper out this month in the Proceedings of the National Academy of Sciences, USA has confirmed the global impacts of these invasive mammalian predators, and reiterates the conclusions of a paper earlier this year in the same journal which highlighted the conservation gains from eradicating these invasive mammals – “management of invasive predators on islands should be a global conservation priority”.

Numbers of threatened and extinct bird, mammal, and reptile species impacted by invasive predators
Numbers of threatened and extinct bird, mammal, and reptile species impacted by invasive predators in 17 regions (Source: PNAS)

To come to this conclusion the authors analysed the IUCN Red List to identify the driving threats to each endangered or extinct species. Over half of recent animal extinctions (birds, mammals and reptiles) were caused by invasive mammalian predators. Cats, rodents, dogs and pigs, by virtue of their widest distribution, had caused the most impacts, but regionally other species are important, such as mongooses, foxes and stoats.

Work by some of the same authors this year also pursued discussion on alternative methods of invasive mammalian predator control, but on islands, it remains clear that invasive predators and naïve native prey cannot co-exist together unmanaged. Eradication through lethal control remains one of the most powerful conservation interventions on islands, and has led to governments such as NZ and Australia calling for widespread culls of invasive rats and cats, and the Honolulu Challenge being a major outcome of the IUCN congress in Hawai‘i which also took place this month.

Read All Posts by James Russell