This species can be, and has been confused with the African Yellow White-eye (Zosterops senegalensis) which has more distinct black lores extending as a fat crescent in front of the eye almost half way out the dark loral line towards the bill. It also has more green on the sides and flanks and a contrasting yellow forehead patch.
White-eyes are currently placed in their own family, the Zosteropidae. However some past genetic research merged them with the Babblers (Timaliidae). For discussion see Roberson. Our field guides call this bird the "Abyssinian White-eye." However, Clements has called this bird the White-breasted White-eye through all editions, a name also followed by Birdlife International and by eBird. This name apparently dates back to check-lists by authored by Morony, Bock and Farrand, and by Sibley and Monroe (all editions). However, some old-world sources such as Howard and Moore, the African Bird Club Checklist, the IOC checklist, HBW, and several African field-guides have consistently called this bird the Abyssinian White-eye.
Some of the more northerly races, including those in Arabia and the Horn of Africa have the lower chest paler which may account for the Clements name See for example this photo of a different more northerly race. The species range is fragmented. See map. Six races are currently recognized. Ours is the southernmost race which reaches its southern limit in northern Tanzania east of the Rift Valley. It has been suggested that two species may be involved in which case our race (Z. a. flavilateralis) with its entire underparts yellow, is a candidate for a future split.
Digiscoped with Panasonic DMC-LZ5 | Nikon FieldScope III | 30XWA | hand-held (no adapter)