Reevaluating introduced herbivores in conservation

Abstract

The impacts of non-native species are the subject of enduring controversy in conservation research and policy. This debate has renewed relevance in light of rewilding approaches that introduce or reintroduce herbivores to restore trophic complexity. However, because large herbivores inherently have strong effects, recent work has warned that the “harms of introduced large herbivores outweigh their benefits” (Bescond-Michel et al., 2025; Nogués-Bravo et al., 2016; Nores et al., 2024). We argue that such conclusions are conceptually and methodologically flawed, particularly because they conflate the predictable consequences of herbivory with harmfulness attributed to a species' non-native status. Without assessing whether effects of non-native herbivores differ from those of native herbivores, these approaches risk depicting the fundamental process of herbivory as problematic. This can misinform conservation and restoration efforts at a time when herbivores, native or introduced, are increasingly recognized as essential for sustaining biodiversity and ecosystem function (Lundgren et al., 2018; Malhi et al., 2016; Pringle et al., 2023; Smith et al., 2016; Svenning et al., 2024; Trepel et al., 2024). ARTICLE IMPACT STATEMENT : Herbivory is a fundamental ecological process; treating it as harm misinforms conservation decisions about introduced herbivores.