Evidence that Kenyan House Sparrows Passer domesticus invaded from multiple sites

Here we characterize genetic patterns across the range of House Sparrows in Kenya using six microsatellite markers. We screened House Sparrows from two remote locations in northern Kenya, Marsabit (n = 24) and Wajir (n = 27), which are separated from other colonized areas in Kenya by minimally developed, arid habitat, and then compared these birds with House Sparrows in 10 more central and longer established Kenyan cities (n = 233) in this range. House Sparrows from Marsabit and Wajir originated from a separate source, probably Somalia and/or Ethiopia, from other Kenyan House Sparrows, probably Mombasa. Furthermore, the genetic characteristics of northern and southern populations indicate that they have not yet mixed, supporting a hypothesis that the large, minimally (human) developed, arid landscape spanning nearly all of northern Kenya, including the 100 000 km(2) Chalbi Desert, is a barrier to dispersal for House Sparrows.