How Great Britain Successfully Eradicated Invasive Coypu: A Historical Case Study

The history of Great Britain's battle against the invasive coypu (Myocastor coypus) serves as a unique example of how a scientific approach and consistent action can lead to the total eradication of an invasive pest. Introduced in the late 1920s for the fur trade, the rodents escaped from farms and successfully adapted to the wild. By the mid-20th century, their population had surged to an estimated 200,000 individuals, posing a severe threat to the economy and ecosystems of East Anglia.

The primary issue centered on the coypu's diet: they aggressively consumed crops such as sugar beet, cereals, and various root vegetables. Beyond agricultural damage, the rodents caused significant destruction to wetland habitats, including the Norfolk Broads, by feeding on native vegetation and destabilizing natural ecosystems. Previous attempts to manage the population through large-scale culling in the 1960s failed, as the population quickly rebounded after the campaigns concluded.

In 1981, the government pivoted to a strategy rooted in scientific planning. Instead of uncoordinated culling, a comprehensive program was launched based on mathematical models, weather data monitoring, reproductive studies, and trap efficiency metrics. This coordination allowed authorities to pinpoint high-density areas and optimize the efforts of the 24 professional trappers deployed for the operation.

A crucial component of the program was the incentive system. Officials recognized that professional trappers might naturally be disincentivized from completely eradicating their livelihood. Consequently, a bonus scheme was introduced to reward the trappers for achieving the ultimate goal—total eradication—rather than merely suppressing the population. From 1981 to 1986, the program conducted hundreds of thousands of trap-nights annually.

The results of this six-year effort exceeded expectations. Through the combination of rigorous scientific forecasting and intensive trapping, the coypu population in Britain was effectively eliminated by 1987. This case study remains a benchmark in agronomy and conservation biology, highlighting that long-term planning and a systematic, data-driven approach are far more effective than short-term, reactive mass culling measures.