Rediscovery of a long-lost lark reveals the conspecificity of endangered Heteromirafra populations in the Horn of Africa

Abstract

The African lark genus Heteromirafra is thought to consist of three threatened species inhabiting mid-altitude grasslands, one in South Africa and two in the Horn of Africa. One of the latter, Archer’s Lark H. archeri of Somaliland, has not been seen with certainty since 1922. We surveyed its type locality as well as a nearby area of grassland east of Jijiga in adjacent north-eastern Ethiopia, where sightings of Heteromirafra larks have recently been made. First, we used a combination of morphological and molecular evidence to show that these recent sightings refer to the same taxon as Archer’s Lark. Second, we used a combination of morphological, molecular and vocal evidence to show that these populations are conspecific with the Liben (Sidamo) Lark H. sidamoensis of southern Ethiopia, but that the Horn of Africa populations are highly distinct from Rudd’s Lark H. ruddi of South Africa. Third, we suggest that the extent and quality of their habitat in north-eastern Ethiopia is small and poor, and that the type locality of Archer’s Lark in Somaliland has been completely transformed. Taken together, these results imply that there is a single species of Heteromirafra in the Horn of Africa (for which the scientific name H. archeri has priority, and which we suggest retains the English name Liben Lark), consisting of two tiny populations separated by 590 km of apparently unsuitable habitats. Environmental niche models suggest that there are no environmentally similar locations elsewhere within the region. Despite the discovery of a second population, the Liben Lark remains a highly threatened species in urgent need of conservation intervention to avert the extinction of both of its populations.