The stock of the original Danish black squirrel is shrinking because they are mixed with red squirrels.
Read about Squirrel Genocide
An invasive species is a species that is not native to a specific location (an introduced species), and that has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health. The criteria for invasive species has been controversial, as widely divergent perceptions exist among researchers as well as concerns with the subjectivity of the term “invasive”.
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