Abstract
The Critically Endangered Archer's Lark (now Liben Lark) Heteromirafra archeri was formerly considered to be endemic to north-western Somalia and known only from the Tog Wajaale Plain, where 18 specimens were collected between 1918 and 1922. Fifteen visits between 1970 and 2008 failed to relocate the species there, although popula- tions are now known from adjacent Ethiopia. We conducted three days of intensive surveys on the Tog Wajaale Plain in May 2010. Despite the three other lark species present being in full display, and H. archeri being recorded to have bred in early June, no Liben Larks were found. Vegetation structure surveys indicated that the plain has a taller and denser growth of grass than either of the other known localities for Liben Lark (the Liben and Jijiga Plains) making Tog Wajaale Plain seem superficially more suitable for the species, which prefers areas of taller grass elsewhere. However, previous large-scale agricultural activities may have altered the composition of grass species and precipitated the observed invasion of exotic weeds, notably Parthenium hysterophorus. Importantly, the Tog Wajaale Plain has a greater density of bushes than either the Liben or Jijiga Plains, possibly making ground-nesting birds more susceptible to predation by perch hunters.
Highlights
Prior to recent work reported in Spottiswoode et al (2013), Archer’s Lark Heteromirafra archeri ( Liben Lark; hereafter H. archeri to avoid confusion) was known only from 18 specimens collected by Geoffrey Archer on the Tog Wajaale Plain, Somaliland, north-‐western Somalia, between September 1918 and June 1922, where he described it as “quite numerous” (Clark 1920, Archer & Godman 1961, Spottiswoode et al 2013)
In this study our aim was to conduct an intensive survey across the Tog Wajaale Plain in order (i) to attempt to find H. archeri, and (ii) to characterise the habitat following methods employed on the Liben and Jijiga Plains (Spottiswoode et al 2009, Donald et al 2010, Spottiswoode et al 2013), such as to allow comparison with vegetation known to support Heteromirafra larks in southern and north-‐eastern Ethiopia respectively
Notable differences between the Tog Wajaale Plain and the two other sites were as follows: of the three sites, the Tog Wajaale Plain had the lowest density of cowpats and had much the lowest proportional cover of bare ground and very short grass
Summary
Prior to recent work reported in Spottiswoode et al (2013), Archer’s Lark Heteromirafra archeri ( Liben Lark; hereafter H. archeri to avoid confusion) was known only from 18 specimens collected by Geoffrey Archer on the Tog Wajaale Plain, Somaliland, north-‐western Somalia, between September 1918 and June 1922, where he described it as “quite numerous” (Clark 1920, Archer & Godman 1961, Spottiswoode et al 2013). The only report of it has been an unpublished sighting in 1955 by John Williams in “fairly open rocky country with scattered and sparse bush and limited grass cover”, 15-‐40 km north-‐west of Boorama, c. 100 km north-‐west of the Tog Wajaale Plain Subsequent searches of this area have failed to reveal any sign of it, and taken together with the atypical habitat and complete lack of supporting evidence, this record has been discounted The Tog Wajaale Plain, fifteen visits by John Ash and John Miskell between 1970 and 2008 failed to turn up any birds and found widespread habitat disturbance within its range (BirdLife International 2015)
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