Damage caused by the American grey squirrel (Sciurus carolinensis) to agricultural crops, poplar plantations and semi-natural woodland in Piedmont, Italy

Abstract

The incidence of damage caused by grey squirrels in the Turin plain was studied to assess the impact this alien species is having on the highly fragmented Piedmont environment, in particular on profitable cereals, poplar plantations and semi-natural woodlands. The survey of damage was conducted both by interviews to local farmers and growers and by direct assessment using the Nearest Neighbour Method on plantations and woodlands, studying randomly chosen plots in the Turin plain to gain a general overview of the situation. The results show a low incidence of damage caused by grey squirrels in the area: little or none was found in semi-natural woodlands and in agricultural crops, apart from maize where less than 1 per cent of fields showed damage, and poplar plantations where 5 per cent had signs of bark stripping. Damage on maize crops was random across the plain, but debarking damage to poplars was mostly concentrated on the western side of the plain, and tended to occur only in particular years. Damage was concentrated close to streams and rivers surrounding fields and plantations. The introduction of the grey squirrel in Italy has already caused ecological damage such as the extinction of the red squirrel in some areas. Nevertheless, little or no information is available on the damage this species is causing on woodlands or agricultural areas. This study is a preliminary survey in order to fill this gap.