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The regional population of the near-endemic Short-clawed Lark Certhilauda chuana is suspected to be declining. Although the exact rate of decline is unknown, it is thought to approach but not exceed the 30% threshold required to qualify this species as regionally Vulnerable.
The Short-clawed Lark is endemic to Botswana and South Africa. Within its range it has a disjunct distribution, divided between two geographical areas, a western population in south-eastern Botswana and adjacent South Africa and a smaller eastern population in South Africa's Limpopo Province. Both populations are found at an altitudinal range of 1 000-1 400 m. The western population's stronghold is the rural areas of south-eastern Botswana (Herremans 1993). In South Africa, the western population has the highest reporting rate in a triangle created by Dinokana in the north-east, Madibogo in the south and Tshidilamolomo in the north-west of North West Province.
Although the western population appears to have experienced a range contraction towards the north, it is probably not significant as the areas where the species has not been recorded in SABAP2 represent marginal habitat and SABAP1 records from the Free State are considered dubious (Engelbrecht et al. 2007). Outside the above mentioned triangle, there are scattered records from the semi-arid thornveld and arid grassland habitats in North West and Northern Cape provinces. The eastern population is largely confined to the Polokwane Plateau Bushveld and Makhado Sweet Bushveld vegetation types (Engelbrecht 2005). The EoO for the eastern population is less than 5 000 km2, while that of the western population is less than 20 000 km2 for the western population. The AoO is unknown, but given the very specific ecological requirements of the species, is certainly only a small fraction of the combined c. 25 000 km2 EoO.
There is no information currently available regarding the global population. Siegfried et al. (1976) crudely estimated the global population to number in the tens of thousands while Herremans (1993) estimated there to be over 10 000 pairs in Botswana alone. Siegfried et al. (1976) estimated that in South Africa as few as 100-300 birds occur within protected areas. Brooke (1984) suggested that the western population of the species comprises approximately 500-5 000 birds. According to Engelbrecht (2005) the Polokwane Nature Reserve represents the stronghold for the eastern population, containing between 80-150 mature individuals (Barnes and Tarboton 1998). More recently, Grosel (2007) estimated the eastern population of Short-clawed Lark to be small, with an estimated effective population size of 760 mature individuals of which at least 120 mature individuals occur in the formally protected Polokwane Nature Reserve. The regional population is thought to be less than5 000 mature individuals. The confidence in this regional population estimate is low.
The global population trend is unknown. Engelbrecht et al. (2007) reported a 73% reduction in EoO in the western population's range and a 28% decline in population size for the total western sub-population (Grosel 2007). According to Grosel (2007), it is thought that declines in both populations was below the 30% threshold which would qualify the species as regionally Vulnerable. Confidence in the regional population trend estimate is low.
Grosel (2007) summarised the threats to the eastern population of the Short-clawed Lark which include habitat loss or change due to urban expansion, agriculture, bush encroachment, lack of fire and an inadequate number of formally protected areas. Their close association with habitats around rural areas pose other threats which cannot be quantified at present, e.g. the effect of predation by free-roaming cats and dogs on breeding success, hunting for food by humans and through further habitat change as a result of bush encroachment or complete denudation of the grass layer through overgrazing and trampling. In South Africa, both populations have high reporting rates in rural and traditional agricultural areas. Although it generally avoids commercial farming areas, the species may be affected indirectly by the use of pesticides, which may reduce its prey base. Most significantly, Grosel (2007) revealed that the Short-clawed Lark has very low levels of genetic variation that may render the species vulnerable to the effects of inbreeding or stochastic environmental events.
The regional population of Short-clawed Lark has been a species of conservation concern since the first regional Red Data books were published in the 1970s (Grosel 2007). In these publications, its status ranged from ‘rare' (Siegfried et al. 1976) to ‘indeterminate' (Brooke 1984), and to Near Threatened (Barnes 2000). Its inclusion in Red Data lists is principally due to its highly localised distribution within its relatively small global range (Grosel 2007). The Short-clawed Lark's preferred habitat is susceptible to rapid detrimental change with incorrect management practices. Recommendations with regard to habitat management in the Polokwane Nature Reserve have been drawn up and submitted to the relevant authority. The species is listed as specially protected wild animal under the Limpopo Environmental Management Act 7 of 2003.
Environmental management legislation should be enforced (Grosel 2007). Education and awareness programmes, aimed at educating commercial game and stock farmers on the Short-clawed Lark's habitat requirements, should be implemented (Grosel 2007). The species requires careful monitoring as Grosel (2007) showed that their numbers can decrease dramatically within a short period due to habitat changes. Responsible veld management in combination with grazing by livestock or game will ensure a healthy environment which will in turn provide suitable habitat for various grassland bird species and other taxa of the Polokwane Plateau, with the Short-clawed Lark as a flagship.
Research on the species' distribution range and relative abundance within its AoO is necessary to establish a framework for monitoring to obtain a better understanding of its current status. In addition, a survey of parts of the distribution of the western population in south-eastern Botswana is required in order to establish whether a similar decline has occurred. The following research questions are posed:
* What is the breeding success and survival rate in rural areas, the stronghold of the species?
* What is the distribution and density of the species within the two populations?