Speciation in the Karamoja Apalis Apalis karamojae

The Karamoja Apalis Apalis karamojae, a threatened species (IUCN Vulnerable), consists of two subspecies, the nominate in Uganda and stronachi in Tanzania plus south-west Kenya, the latter distinguished by being slightly darker with more extensive grey on the underparts. Recent evidence, however, indicates that the two taxa are highly divergent in voice. Analysis of recordings of their duets confirms this: the nominate sings very rapid phrases of short simple notes whereas stronachi uses musical slurred whistles, very different in note length and strongly different in max. frequency; moreover, in two independent tests nominate birds failed to react to stronachi songs, indicating reproductive barriers between them. Re-examination of specimen material and a review of online photographs confirm the greater amount of grey on the underparts of stronachi. Taken together these differences indicate that stronachi merits species rank. The two taxa are specialists of mature whistling-thorn Vachellia drepanolobium, which is cut for fuelwood and to open up pasture, so that their long-term survival is likely to depend on the integrity of protected areas.