With few natural predators, they are now listed as a "pest species" by Natural England.
There could be as many as 2 million of the snakes on Guam, where they have no natural predators.
They have no natural predators and can reach lengths up to 18 feet.
Switzerland is not the only country to struggle with the question of how to help humans and natural predators coexist without friction.
CNN: Switzerland's only wild bear is killed as a danger to humans
In the absence of natural predators deer populations are continuing to expand, threatening biodiversity and causing road traffic accidents and crop damage, say researchers.
That, combined with warmer waters, pollution and policies that protect natural predators like seals, have all contributed to fewer fish that triggered the mandatory cuts.
The tiered structure also prevents erosion and provides a habitat for insects, birds and butterflies, which act as natural predators, reducing the need for pesticides.
They quickly multiplied with no natural predators on the island.
Garden gnomes have served as symbols of defiance on many levels as guardians of the natural environment against intending predators, or simply as cheerleaders for the colourful suburban plot, under threat from student japesters in France or, more seriously, from the fashionable proponents of ever more sophisticated garden design.
More to the point, according to Professor Bruce Ames, an eminent biochemist at UC-Berkeley, our foods contain 10, 000 times more natural, endogenous pesticides the result of plants evolving with their own natural defenses against fungi and predators than synthetic ones, but many of the latter are actually less harmful.
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