The individual first spotted and recorded on May 9th represents only the second country record; the first was in May 2011. Subsequently, I made trips on May 23 and 31 and again on July 2-3, primarily to assess the status of this and other species. On subsequent trips I found two more actively singing males, plus on July 2-3 two territorial pairs that displayed very agitated behavior by my presence, bringing the total number of territories to four.
The photos above were made on July 2. I was able to photograph one of those agitated individuals as it hopped actively around in low bushes and one small tree no more than 3-4 meters high. Both pairs were repeating an alarm call over and over - the non-musical, dry, short, rapid trill with no high notes thrown in.
Assuming these birds are nesting - their behavior strongly, but not conclusively suggests they are - this would represent a significant breeding range extension southward. BirdLife International Data Sheet for Melodious Warbler shows the southern extent of their breeding range to be in Croatia north of Split, a distance of more than 70 miles (>110km).