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Sclater's Lark Spizocorys sclateri is a sparse, under-recorded semi-desert specialist, restricted to western South Africa and southern Namibia. Previous authors pointed out that there was no evidence that this species had undergone a range contraction, but pending more conclusive atlas coverage, new atlas data suggest that Sclater's Lark warrants monitoring.
Sclater's Lark is endemic to the barren, open landscapes of western South Africa and southern Namibia. The centre of distribution lies in Northern Cape's Nama Karoo Biome, where this species occurs in a highly fragmented fashion across a vast area. An apparently isolated outlying population is found in Western Cape near Beaufort West (Dean 1997). The species is most abundant on the stony plains of Bushmanland, between Brandvlei and Pofadder, but even there is reported as scarce and local (Dean 1997). Its movements are poorly understood, and, depending on localised rainfall events, it may be a nomadic opportunist at the fringes of its range. However, in the core of its range, it is considered sedentary or at most locally nomadic, and may breed in the exact same locality in consecutive years, irrespective of rainfall (Lloyd 1999). Indeed, Lloyd (1999) recorded the highest breeding densities in drought years. Vagrants occasionally occur outside the normal range, suggesting sporadic long-distance dispersal (Clarke 1981). The species is uncommon and highly localised in southern Namibia; however, incomplete sampling likely contributes to its apparent rarity there, and recent sight records suggest that it is more widespread in Namibia (Barnes 2000).
Based on SABAP1 data, Barnes (2000) estimated that the AoO may be 68 600 km2, of which c. 63 000 km2 is located in Bushmanland in Northern Cape. The estimated regional AoO was calculated at c. 47 500 km2 in the previous assessment (Barnes 2000), but the latest atlas data suggest that the species may now have a regional AoO of only c. 8 000 km2, representing a decrease of 83%. However, virtually the entire range falls within arid and sparsely populated parts of Northern Cape and consequently the species has almost certainly been widely overlooked. If the species is in decline, the rate of decline is believed to be less severe than suggested by atlas data. Sclater's Lark has been recorded in a single IBA, namely Mattheus-Gat Conservation Area (SA034).
Neither the regional or global population has been quantified but the species is considered uncommon and localised (BirdLife International 2014). It would be very challenging to provide an accurate population estimate given the bird's small size and unobtrusive nature, and the remoteness of its barren habitat. Lloyd (1999) reported a density of 0.72-1.75 nests per 100 km in a linear transect.
A comparison of SABAP1 and SABAP2 data indicates a decrease in EoO and AoO, which may imply a decline in the regional population. However, due to the lack of coverage throughout the species' range, it is unwise to draw conclusions from this analysis and no population trend justification is proposed here.
Sclater's Lark is a naturally sparsely distributed and localised specialist of arid environments with low reproductive output, and is seldom common, even in apparently optimal habitat (Dean 1997). However, it is also easily overlooked and is likely more widespread and numerous than current records suggest. Neither breeding nor clutch size seem to be closely related to rainfall (Lloyd 1999), but the potential effects of climate change on Sclater's Lark have need to be properly investigated, and may be severe considering that the species appears to be less nomadic and mobile than other small granivorous passerines (Barnes 2000). Although the species is poorly represented in formally protected areas, it persists on privately owned farms, and has likely benefited from stock watering points (Lloyd 2005). Nevertheless, its range is small and fragmented, and appears to be contracting. It may also be prone to extreme fluctuations in EoO and numbers of mature individuals.
No conservation measures are currently underway, and the species is poorly represented in protected areas. Because it is under-reported, population declines may go unnoticed.
Before an effective management plan can be compiled for this species, more data on its population size and distribution are required. An investigation into the threats faced by Sclater's Lark, and the potential mitigation measures to counteract such threats, should follow. Practically, responsibility for the species' long-term conservation will lie with private land-owners and appropriate management of their properties. Education of land-owners and compilation of management guidelines provided by conservation institutions will be beneficial in this regard.
* Complete atlas coverage throughout the historic range of the species, preferably by an experienced observer familiar with this species and its ecology, is important.
* The global and regional population should be estimated, possibly with the help of satellite imagery.
* Investigate population dynamics and reproductive output, to ensure effective management principles.
* Assess the nature and severity of threats to Sclater's Lark.