Habitat fragmentation effects and variations in repertoire size and degree of song sharing among close Dupont’s Lark Chersophilus duponti populations

Abstract

We describe the song type repertoire variation and degree of song sharing in three isolated and declining Dupont’s Lark (Chersophilus duponti) populations located close to each other in eastern Spain, studied over two years. We found no differences between sites either in song rate or individual repertoire size. We detected great differences in song type diversity at the population level, ranging from five to 18 song types. We used, for the first time, the SIMPROF test, a method that objectively discriminates significant groups resulting from agglomerative clustering methods, to study geographic variation in bird song. We found four microdialects in the study area with a low degree of song sharing among populations, which may be related to the influence of habitat fragmentation and the song learning process and ecology of the species. We detected different patterns of song sharing among sites. All males of two populations shared about 80–100 % of their song types throughout the habitat patch. At the other site, we found two microdialects within the same habitat patch, where song types were only shared among neighbouring males. The high degree of song sharing found can be explained by the reduced dispersal movements of the species. We also detected a high consistency in the song types between years. The creation of corridors and habitat management in potential habitat patches surrounding Dupont’s Lark populations could act as stepping-stones, improving the connection between populations and thereby song transmission between patches.