Bringing back native predators to tackle invasive species crisis

Invasive species are one of the greatest threats to biodiversity globally and are the main cause for the extinction of vertebrates in the last century, with an estimated cost of at least $162 billion (USD) a year.

Native predator populations have been depleted globally, despite being essential for the functioning of the ecosystem and biodiversity. The absence of native predators facilitates the spread of invasive species leading to the extinction of native species throughout the world.

The research, published today (16 June) in Global Change Biology, found that restoring native predators could provide a solution to a variety of the most damaging invasive species globally. According to the study, the evolutionary naivety of invasive species to native predators, coupled with a lack of spatial refuges from predation could underpin the abilities of native predators to provide effective control of certain established invasive species.

The research team have previously shown how the recovery of the native pine marten in the UK and Ireland has resulted in landscape-scale declines of the invasive grey squirrel. Building on this research, the team have now evaluated native predator reintroduction and restoration as a viable nature-based solution to the invasive species crisis.

Lead author, Dr Joshua Twining from the School of Biological Sciences at Queen’s University Belfast and the Department of Natural Resources at Cornell University, says: “In a modern world that is daunted by environmental crisis and ecological collapse, it is more important than ever to realise the potential of restoring native predators to ecosystems from which they have been previously lost. This applies globally but is especially applicable in Britain and Ireland where we have persecuted all our large-bodied predators into extinction with no natural means of recovery.”

One example shows how re-introducing the native lynx could help to manage one of the most damaging invasive species to the environment in Europe, the sika deer. Sika deer are considered a pest as they graze on crops and “ring” trees, stripping the bark from the base and causing the tree to die. They are also thought to contribute to the spread of diseases such as bovine and avian TB. The new research provides strong evidence that the lynx could impact sika deer populations in Britain and Ireland. It also shows how the lynx and wolf recovery in Europe could limit raccoon dogs below the threshold for rabies persistence, which remains a huge threat to human and animal health.

Further afield, the research examines how the predator Florida panther, one of the first species added to the U.S. endangered species list in 1973, could contribute to control of invasive feral pigs. Feral pigs are widely considered to be the most destructive invasive species in the United States, causing damage to the ecosystem, wrecking crops and hunting animals like birds and amphibians to near extinction. The research shows how reintroducing the Florida panther could effectively provide a nature-based, efficient, and cost-effective solution to limit the further spread of feral pigs.

Dr Twining concludes: “Our work demonstrates the plausibility of a nature-based approach to the control of certain invasive species around the world. Native predator restoration can provide effective solutions to some of the most damaging of invasive species and thus buffer our natural systems against some of the worst of human impacts.”

The study, funded by the Natural Environmental Research Council, involved a team of researchers from Queen’s University Belfast, University of Aberdeen, Heriot-Watt, Cornell University and the National University of Ireland, Galway.