Lesser Short-toed Lark is two species
THE Lesser Short-toed Lark complex, which includes the closely related Sand Lark and Asian Short-toed Lark, is a broadly distributed group spread across the Palearctic and North Africa. Due to morphological similarities, its taxonomy has been heavily debated in the past, with up to 16 recognised forms spread from the Canary Islands to north-eastern China.
A study by Ghorbani et al (2020) analysing the molecular data of the birds revealed four distinct lineages within the complex that separated between 1.6 and 3.2 million years ago. The authors indicate that Lesser Short-toed Lark would be better treated as four: the heinei clade; raytal clade (Sand Lark); rufescens clade; and the cheleensis and leucophaea clade (Asian Short-toed Lark). They stated that additional data was required before any formal taxonomic revision should be undertaken.
A paper by Alström et al (2020) corroborates Ghorbani’s findings, supported by mtDNA, morphology and bioacoustics as well as nuclear DNA, song-flights, geographical distribution, habitat, and bioclimatic data. The paper proposes that the complex is best recognised as four species: Mediterranean Short-toed Lark Alaudala rufescens; Turkestan Short-toed Lark A heinei; Asian Short-toed Lark A cheleensis; and Sand Lark A raytal.
On plumage characteristics, Mediterranean and Turkestan Short-toed Larks are extremely similar, and differ mainly in heinei being overall less rufous-tinged than rufescens, with on average thinner breast streaks. Asian Short-toed Lark has paler, less blackish-brown remiges and rectrices than its sister taxa, and averages significantly more white on the outermost tail feather. Sand Lark differs most on plumage, and is characteristically thinly and faintly streaked above. Notably, Mediterranean and
Turkestan Short-toed Larks were found to differ on song.
In December 2020, the IOC World Bird List accepted the proposal to split Turkestan Short-toed Lark from Mediterranean (Lesser) Shorttoed Lark; the new taxon was added to Version 11.1 of the list. ■
Reference
Ghorbani, F, Aliabadian, M, Zhang, R, Irestedt, M, Hao, Y, Sundev, G, Lei, F, Ma, M, Olsson, U and Alström, P. 2020. Densely sampled phylogenetic analyses of the Lesser Short-toed Lark (Alaudala rufescens) – Sand
Lark (A raytal) species complex (Aves, Passeriformes) reveal cryptic diversity. Zoologica Scripta 49: 4, 427-439.