Field characters, taxonomy and distribution of the ‘buff-bellied’ forms of the Grey Penduline Tit Anthoscopus caroli (Sharpe) in East Africa

Abstract

We review the distribution and taxonomy of the buff-bellied subspecies of the Grey Penduline Tit Anthoscopus caroli in East Africa using photographs of specimen material as well as of birds in the field. Our study reveals three distinct taxa in the group, including, in addition to the currently recognized sylviella of eastern Tanzania and sharpei of south-central and western Tanzania, recognition and reinstatement of the form rothschildi from eastern Kenya (previously synonymized with sylviella). We show that contrary to literature accounts, sylviella has richer underparts and darker upperparts than sharpei, and the range of sharpei extends southeast from Tabora to the Iringa area of Tanzania and not northwards into southwestern Kenya, as had been previously thought. Meanwhile, we extend the range of sylviella from eastern Tanzania to areas west of the Rift Valley in the Serengeti National Park of Tanzania as well as southwestern Kenya, both areas previously considered occupied by sharpei. We further demonstrate that these two taxa intergrade where they meet in the southern reaches of the Serengeti National Park, and that sylviella also intergrades with rothschildi across a small area to the east of the Rift Valley in Kenya immediately south of Nairobi. Further work may show birds in the Chyulu Hills, Kenya, to be a distinct form, while birds in the central Kenya Rift Valley remain only tentatively assigned to sylviella.