Using native predators to control invasive species


Humans have killed larger native predators and other species they have competed with or feared throughout evolution. This process has been particularly successful in Ireland and the UK, where the lynxes and wolves that people once shared their lives with are no longer present.

Humans have also transported valuable species outside of their natural range, inadvertently creating invasive species by introducing plants, animals and microorganisms into ecosystems where they did not evolve. This has led to the extinction of native species by competing with them, eating them and exposing them to new diseases. Over the past century, studies have shown that invasive species have been the primary cause of vertebrate extinction.

Mounting evidence shows that these once despised native predators are now essential for controlling invasive prey.

Love for native predators

Eradication of native predators has contributed to the current invasive species crisis, according to new research. However, Irish researchers carried out a series of surveys between 2007 and 2019. It included public sightings of gray squirrels and pine martens to see how the return of a native predator can cause the rapid decline of a species. long-established invasive, gray. squirrel, across entire landscapes.

Joshua Twining, a population ecology researcher at Cornell University, also a postdoctoral researcher at Queen’s University Belfast, collaborated on the study with Xavier Lambin and five other researchers.

Twining’s team examined populations of both species to see what factors influence a native predator’s ability to control an invasive species after restoration. These factors include the invading prey’s inability to recognize or respond to the threat of a newly scavenged predator, the predator’s ability to switch prey, and the availability of hiding places for the prey to flee.

predator-prey relationship

Native predators preferentially hunt invasive prey by a factor of two or even three, from wolves hunting non-native Corsican mouflon in the Mercantour mountains of southeastern France to red-banded snakes preceding invasive bullfrogs in China.

Understanding why this is the case can help determine when and where native predators can help control invasive species.

For example, Lynx has a proven ability to suppress deer populations by changing the species of deer they hunt. There are no areas accessible to deer which are reserved for lynx. The combination of these factors suggests that restoring lynx populations will benefit ecosystems where sika deer are a problem. Where alternative prey, such as roe deer, are scarce or absent, such as in Ireland and Great Britain, the lynx is likely to have a greater impact on these invasive populations.

Read also: How invasive species thrive in the Mediterranean

Accommodate native predators

The natural recovery of some top predators in mainland Europe, such as bears, lynxes and wolves, is well underway. This challenges long-held beliefs about the need for carnivores to have pristine habitat. Despite intensive urban sprawl and agriculture, the only requirement was that people stop killing predatory species to recolonize their former range. Extinct predators will not recover naturally in Britain as it is surrounded by sea. Any attempt to reintroduce them would require societal agreement, which currently does not exist.

The ecological rationale for restoring native predators is to help control and limit the spread of invasive species, according to our findings. However, living near large carnivores has its downsides, including the loss of livestock and sometimes even pets. This is unavoidable, but it can be mitigated by proactive management.

Twining points out that while people are to accept the restoration of any native predators, the benefits, such as reduced harm from invasive species, must be weighed against plans to mitigate the costs.

Related Article: Here’s How Non-Human Species Are Driving Others To Extinction

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