Common Bulbul

Pycnontus barbatus tricolor

aka Yellow-vented Bulbul, Dark-capped Bulbul or Black-eyed Bulbul.
This is a very well-known East African bird. This race is the most widespread, with another two subspecies known from the area: dodsoni from east and north Kenya, and layardi around Taveta in Kenya and in Tanzania east of the Rift Valley.