Invasion status of Asiatic red-bellied squirrels in Argentina

The only known introduction of a squirrel species into South America is the case of the Asiatic red-bellied tree squirrel Callosciurus erythraeus that was introduced in the Pampas Region of Argentina in 1970. To inform management programmes, we analysed the current distribution, expansion rate, and abundance of the red-bellied squirrel in Argentina, and identified invasion pathways. Apart from the first and main focus of invasion, three other invasion foci have originated as a consequence of intentional releases between 1995 and 2000. The main invasion focus already extends over >1300 km², where estimated density averaged 15 ind ha^?1 and numbers of squirrels may reach 100,000 individuals. The area invaded in the other three invasion foci varied between <1 and 34 km² and mean densities were around 3–5 ind ha^?1. Squirrel abundance and residents’ attitude towards this introduced species in the main invasion focus make eradication unfeasible, though management actions such as control, containment and mitigation of damages should be undertaken. Eradication of the relatively small invasion foci must be immediately evaluated, with priority given to valuable conservation areas under high invasion risk.