In the early 1990s the Sardinian warbler began nesting in Cyprus, and now has two breeding populations, in the west and north of the island. Observations of the western population show that its range is still expanding and that the endemic Cyprus warbler has declined in the areas colonized by the Sardinian warbler. However, the Cyprus warbler is still present in most of these areas, and hence, although the Cyprus warbler is a species of European Conservation Concern, the current situation requires further study rather than alarm. The Sardinian warbler is the more numerous species at lower altitudes, whilst the Cyprus warbler is more common at higher altitudes, especially above 500 m. Within their areas of overlap, both Cyprus and Sardinian warbler populations occur throughout almost all habitats; natural, semi-natural and agroecosystems. We recommend that monitoring should continue, with more detailed ecological studies.