Puzzling failure of wild boar to colonise Mediterranean islands

Puzzling failure of wild boar to colonise Mediterranean islands  

Sus scrofa cristatus photo © Bernard Dupont

Before the islands of the Mediterranean were reached by humans, they were inhabited by mammals capable of swimming across sea barriers: hippopotami, elephants and deer. However, no Mediterranean island was naturally colonised by wild pigs, which is surprising because the European wild boar swims well and, as an omnivore, should have been suited to the relatively unreliable supply of food on islands. 
 
Robin and the Honey Badger, 15 March 2016
 
Photograph
Wild boar swimming