A team of scientists have found that a significant number of vertebrate extinctions on islands could be prevented by removing invasive mammals. Human-introduced animal species, including cats and pigs, cause the destruction of island ecosystems, resulting in the extinction of unique animal species. The team’s findings can be used to decide where to focus conservation efforts. The details are in a paper just published in the journal Nature Communications.
Islands are isolated ecosystems that tend to have high levels of biodiversity. Unfortunately, they are also vulnerable to damage by invasive species. Humans have introduced invasive mammals to islands, sometimes inadvertently, and the local species can’t always compete. Animals such as pigs and goats cause damage to the islands’ flora. Rats, domestic cats, and other predators hunt birds and small animals. Rats, for example, are often seen eating the eggs and chicks of native bird species. When steps are made to eliminate these invasive mammals, biodiversity can be restored to the islands.
A team of researchers analyzed threatened and extinct animals from over 1,000 individual islands. They found that some invasive animals were more dangerous than others. Most extinctions were caused by rats, pigs, cats, mustelids, and mongooses. Controlling these specific animals would prevent most island extinctions. The team also found that the island’s environment mattered. According to mathematical models, removing invasive species on small, dry islands would prevent more extinctions than removing invasive mammals from large islands with wet climates. Overall, the researchers found that eradicating invasive mammals could prevent 41% to 75% of island extinctions.
The research team hopes that their findings will lead to more focused conservation efforts. Conservation funding is limited and the team believes that eliminating invasive mammals would be the best way to prevent extinctions. By concentrating on the most destructive species, such as rats, up to 75% of island extinctions can be prevented. The team also developed a model that shows which islands would be helped the most by invasive animal removal. Small islands with dry climates would benefit the most from these types of conservation measures. The authors recommend that their results be used to efficiently utilize conservation funds.
Erin E. McCreless et al. Past and estimated future impact of invasive alien mammals on insular threatened vertebrate populations. Nature Communications (2016).