Burundi, Congo [The Democratic Republic of the], Eritrea, Ethiopia, Kenya, Malawi, Rwanda, Tanzania [United Republic of], Uganda, Zambia.
Extreme south-central Eritrea south to central and southern Ethiopia; eastern DRCongo, south-western Uganda, Rwanda and Burundi; Mt Elgon (Uganda-Kenya border) and western and central Kenya; north-eastern and southern Tanzania (Eastern Arc Mts); and north-eastern Zambia and northern Malawi (Nyika Plateau).
 
Population
Estimated population is unknown (2010).
Slender-billed Starling (Onychognathus tenuirostris) [XC517326]
by Louis A. Hansen from Suni camp, Chita Forest, southern Udzungwa Scarp, Tanzania (call)
Slender-billed Starling (Onychognathus tenuirostris) [XC537891]
by Brendan Sloan from Lembus Forest, Elgeyo-Marakwet County, Kenya (call)
Subspecies
Proposed subspecies theresae (described from northern Aberdares, in Kenya) considered largely inseparable from birds in rest of species' range.
The following 2 subspecies are recognised:
tenuirostris (Rüppell, 1836) - Eastern.
theresae Meinertzhagen, R, 1937 - Eastern Democratic Republic of the Congo to Kenya, Tanzania and northern Malawi.