Conserving Rodent Pests in Transition Toward Endangered Status.

Rodent management has lacked explicit statements of desired outcomes and heavily borrows from invasive non-native species terminology for which eradication is an aspirational outcome. Rodent control, often reliant on rodenticides, invariably takes place in the context of ecosystems heavily modified by agriculture. Together, they are potent drivers of rodent decline and endangerment. I use the IUCN Red List of Threatened Species which is conservative to explore how widespread the transition from rodent pest to endangered rodent is. Twenty-three percent of extant rodent species are of some conservation concern, and 64 species are threatened by persecution/control. The expansion of agropastoral production threatens 27% of rodent species, either alone or in conjunction with persecution. The transition from pest to endangered species can be rapid, as has been by the case for the now critically endangered European hamster (Cricetus cricetus). For some species, increase in the amplitude of outbreaks and hence incentives to control rodents are associated with the intensification of agricultural practices. Habitat fragmentation triggers metapopulation processes with thresholds for persistence depending on dispersal abilities as illustrated by the Eurasian water vole (Arvicola amphibius). Some extant species with low dispersal abilities are likely part of an extinction debt. The magnitude of the footprint of humankind and the potency of control tools available to farmers call for reasoned management objectives and careful monitoring of impacts where control is used for protecting crops and livelihoods.