Successful eradication of a suburban Pallas’s squirrel Callosciurus erythraeus (Pallas 1779) (Rodentia, Sciuridae) population in Flanders (northern Belgium)

Abstract

Despite a growing catalogue of eradication projects, documented successful vertebrate eradications on the mainland remain scarce. Reporting on successful campaigns is crucial to counter pessimism on ambitious programmes to tackle invasive species and to allow conservation practitioners, wildlife managers and scientist to learn from previous experience. Moreover, there is a need for basic information on the effectiveness of control methods and management strategies that can be used. In this note we report on a successful low-tech eradication campaign of a local population of Pallas’s squirrel Callosciurus erythraeus, a species of tree squirrel with documented ecological and socio-economic impacts in its invasive range. The population was eradicated from a suburban park of about 15 ha using baited mesh wire life traps, in five consecutive capture campaigns between October 2005 and January 2011. Using maximum likelihood estimation from catch-effort data we calculated initial densities in the park at 3 squirrels ha⁻¹. Although control started quickly and the extent of the invasion was limited, the campaign took over 5 years and required an estimated investment of over €200,000 including 1.5 years of post-eradication surveying. We provide basic data on the methods used to eradicate this invasive rodent. Critical success factors and possible improvements with respect to the specific context of this case are discussed. Adding this species to the list of species of EU concern currently under development could provide incentive to minimise impact of this tree squirrel at the continental scale.