This bird was some distance away in a dense hedgerow. I am fairly certain that it is a female Subalpine Warbler but the taxonomy of this species is still being investigated. Possibilities in Corsica are the subspecies cantillans and moltonii (the latter treated by IOC as a separate species) but I don’t think that they can be separated except by call.
Country: France
Location: near Bastia airport, Corsica
Family: Sylviid Babblers (Sylviidae)
Species: Subalpine Warbler (Sylvia cantillans)
Date taken: 25/09/2014