Systematic and persistent bias against introduced species

Critics of invasion biology have argued that conservation science is biased against introduced species. We reviewed 300 randomly selected articles that described the ecological effects of introduced species and assessed whether they were framed negatively, neutrally, or positively. We then asked whether their framing was related to harms as defined by the conservation community; to knowledge about the introduced species, using the species’ taxonomy, habitat, and region as proxies; and to the journal’s focus and prestige and the author's country of affiliation. We also analyzed whether framing differed across space and time. If invasion biology is unbiased, one would expect that negative framing would be more common for introduced species associated with harm. We found that introduced species were framed negatively in two thirds of the articles. Introduced species were framed negatively regardless of attributed harms and across taxonomies, journals, the globe, and time. Our results support that introduced species are persistently regarded as harmful, a bias that raises questions about the validity of the claims made about them.