The time factor

According to statistical prediction models that simulate the possible expansion of the grey squirrel in the medium term and that have been specially formulated and believed to be reliable in the scientific international community, the grey squirrel will be able, in time, to colonize the Alps, the Apennines and the bordering countries of France and Switzerland. For this reason, several national and international bodies have repeatedly requested that Italy should intervene limiting the species expansion.

Based on the results of such models it is believed that in 20-40 years from 1996 the species can colonize the western Alps in the provinces of Cuneo and Turin and in about 30 years reach France. The populations in Lombardy would take 20-40 years to colonize the area along the Ticino river and Lake Maggiore and the first grey squirrels could easily reach Switzerland in the decade 2030-2040. Once Swiss and French colonization is successful, the colonization of other parts of Europe will be only a matter of time.

Unfortunately, the discovery of new populations of grey squirrel in Lombardy suggests that the colonization of Switzerland by the grey squirrel could be much closer in time. The future of the grey squirrel in Italy and the management decisions should be evaluated taking into account the planned expansion possibilities of the species. A large part of Europe host environments that could be suitable for greys presence and the species can therefore colonize other countries starting from Italy. This represents a serious risk to the survival of the red squirrel in the whole of its distribution area.

Maps produced by the European Squirrel Initiative using the results of the simulations reported in Bertolino et al. 2008. Biological Conservation 141: 2564 2575.