Moult of the Sardinian warbler

Abstract

The Sardinian warbler Sylvia melanocephala is a very common breeding resident in the Maltese Islands. It frequents most habitats including urban gardens. Formerly it was a winter visitor only, but became established as a breeding resident at the end of the last century (Sultana et al. 1975l. However, there are still indications of influxes in late autumn and winter (Sultana & Gauci 1976) and also evidence of spring passage in some years (Gauci & Sult~na 1978l.

Between the years 1974 and 1978, 511 moult cards (158 for adults and 353 for juveniles) were filled in by the authors for the MOS Ringing Scheme- Valletta. Moult was recorded following the criteria used in the moult enquiry of the British Trust for Ornithology, as described by Snow (1967). A score of 0 was allotted to an old feather, 1 to a feather missing or in pin, and 2, 3 and 4 to feathers up to one-third, two-thirds and nearly fully-grown respectively. New fully-grown feathers were givenescore of 5. Fully-grown feathers still having a sheet of wax at the base have been scored as 4. Adult post-nuptial moult and post-juvenile moult are described separately. As will be seen later, a high percentage of adult birds were trapped when the primary score had already advanced to tw~nty or more. This bias is due to two factors: Little ringing was done in June and July; also, birds are much less active in the early stages of moult.