Endangered Times - Spring/Summer: 'SEARious' Science

The role played by invasive species in interactions with endangered and threatened species in the United States: a systematic review

The Convention on Biological Diversity (COP 10) has reported “invasive species as 2nd greatest cause of species extinction”, but what is the evidence that such extreme effects are accurate?

In keeping with the invasive species theme from our Species Pick focus, this paper from 2018 looks at the issue of invasive species impacts on endangered and threatened species in the United States. From the paper: “Invasive species are considered to be a leading cause of the decline of threatened species. However, this view has been disputed because much of the evidence base is anecdotal. This systematic review, through an extensive, repeatable search using agreed selection criteria, examined the available scientific evidence on invasive species’ interactions with the 1363 endangered and threatened species protected under the United States Endangered Species Act (ESA). This paper found the following: "Predation by invasive vertebrates on birds on islands and competition between invasive plants and endangered or threatened plants on the mainland were the main mechanisms of impact. The results of this study contrast markedly with a previous study which found that 49% of imperilled species in the United States were threatened by invasive species. Further research is essential in order to evaluate the impact of invasive species on imperilled species on the ESA list; this would help to reduce the high degree of uncertainty regarding the threat of invasive species due to the lack of empirical information."

Download and read the entire paper here.

Further reading:

Invasive predators and global biodiversity loss

A similar study from 2013, What is the evidence that invasive species are a significant contributor to the decline or loss of threatened species? A systematic review map resulted in very different findings.

Image credit: The 100 top invasive species, International Union for the Conservation of Nature (IUCN)