Cyprus and Sardinian Warbler

when we first went to Cyprus in 1996 the only Sardinian Warblers were in a little pocket near Pollis; by 2008 they were down on the south coast but I could not get over just how abundant they are now and how Cyprus Warbler seems to be getting harder to find. Is there direct competition between the two species, they are in the same habitats and Sardinians seem to exploit habitats not used by Cyprus Warblers. I assume something must have been written about the colonisation of the island by Sardinians but not looked for any refs yet -- Cyprus Warblers also seem to have got a lot more wary of humans with cameras!