SPECIES

Short-clawed Lark Certhilauda chuana Scientific name definitions

G. Derek Engelbrecht
Version: 2.0 — Published February 23, 2023

Demography and Populations

Introduction

Short-clawed Lark breeding success is poor to moderate, but the losses are offset by the species being multi-brooded. Replacement broods are common, with up to seven nesting attempts/pair recorded in one season, while up to three repeat-brooding attempts/pair have also been recorded. Little is known about the longevity of Short-clawed Lark, but one individual occupied the same territory for just short of 16 years, the oldest known lark on record. Males defend territories ranging in size between c 4 and 10 ha, with territories generally being smaller in optimal habitat. The population status of Short-clawed Lark appears to be stable, perhaps even increasing, but research has shown that its preferred habitat can become unsuitable within a short period if the drivers that create and maintain its habitat structure, i.e., heavy grazing, wood harvesting, and fire, are withheld, leading to bush encroachment.

Measures of Breeding Activity

Age at First Breeding

Not known, but females likely start breeding in the season following their natal year. It may be later for males as they first have to establish and maintain a territory.

Intervals Between Breeding

Adults on the Polokwane Plateau breed annually, but in Botswana, some pairs do not nest every year (6, 5).

Clutch Size and Number of Clutches per Season

Botswana: in one study, clutch size before or at hatching was either two eggs (n = 1) or three eggs (n = 4). The estimated clutch sizes of nests found with nestlings followed a similar trend with two 2-egg clutches and five 3-egg clutches (6).

Polokwane Plateau: Of 54 clutches where the clutch size was reliably determined, two clutches were of single eggs (both followed a recent failed attempt), 36 were 2-egg clutches, and 17 were 3-egg clutches (DE, unpublished data). There is seasonal clutch-size variation on the Polokwane Plateau, with larger clutch sizes during the peak breeding season and smaller clutches at the beginning and end of the breeding season. See Eggs.

Annual and Lifetime Reproductive Success

Hatching Success

Hatching success, defined as the percentage of the total number of eggs laid that hatched, was 45.5% in one sample (n = 40 nests; DE, unpublished data). The hatching rate, i.e., the percentage of nests in a sample in which at least one egg hatched, was 63.0% (n = 55 nests; DE, unpublished data).

Reproductive Success

In Botswana (6), at least six of ten nests monitored were depredated, suggesting breeding success is low.

On the Polokwane Plateau (DE, unpublished data), at least one nestling fledged from 23 (42%) of 55 nests under observation (DE, unpublished data). Of 43 eggs present at hatching, 40 hatched (93%) and 28 (70%) young fledged (n = 21 nests). Daily nest survival rates were slightly higher during the nestling period (0.96) than during incubation (0.94), with an overall Mayfield nest survival of 24.5% (DE, unpublished data). Pairs fledged an average of 0.93 ± 1.6 SD young per nest (n = 55 nests), and 1.55 ± 1.15 SD young per successful nest (i.e., nests that fledged at least one young) (n = 23 nests).

There is no information on the lifetime reproductive success of the species.

Number of Broods per Season

The limited data available for the western population suggest this population is single-brooded, but replacement clutches are common (6). The relatively poor breeding success of the eastern population on the Polokwane Plateau means replacement broods are common. Pairs on the Polokwane Plateau have up to five breeding attempts within a season, with up to three being successful, fledging up to seven nestlings (5). Multiple repeat-brooding attempts such as these are rare among larks (5).

Life Span and Survivorship

On the Polokwane Plateau, one banded female was recaptured 3 years, 5 months, 28 d later (45). A banded territorial male on the Polokwane Plateau lived at least 15 years, 8 months, 1 d, making it the oldest known lark in the world at the time (43).

Disease and Body Parasites

Body Parasites

Ticks are frequently found on the head and neck region, with as many as 13 counted on one individual (DE, unpublished data). Although three individuals in the Polokwane Game Reserve were checked for ectoparasites, such as mites, lice, and louse-flies, none were found (52, 53).

Causes of Mortality

Predation is the leading cause of nest failure, followed by flooding and trampling by livestock and game (6, 5). Known nest predators include banded mongoose (Mungos mungo). A Pallid Harrier (Circus macrourus) once captured an adult, but the lark escaped apparently unharmed (DE, unpublished data). Other known causes of mortality include subsistence hunting of adults and routine road verge maintenance activities, e.g., mowing that destroys nests.

Population Spatial Metrics

Territory Size

Males defend territories of 6–10 ha, but there is a degree of overlap between neighboring territories (5, 32). In optimal habitat at Kgoro Pan, southeastern Botswana, the density is much higher, with 1.3 territorial birds/ha reported by Herremans (31). Field observations in optimal habitat in rural areas of the Polokwane Plateau suggest territories may be smaller (3–4 ha) in high-density areas (DE, unpublished data).

On the Polokwane Plateau, males occupy and defend multi-purpose territories for feeding and breeding throughout the year and over successive years (5, 43). One male occupied the same territory on the Polokwane Plateau for 15 consecutive years (43). Although females typically occupy a territory for only a single season, they also actively participate in activities associated with territorial defense. Territoriality seems more fluid in the western population in Botswana, as color-banded males could not be relocated later in the same season (31). Territorial defense is most intense during the breeding season (46). There are subtle shifts in territorial boundaries across years as neighboring males may need to adjust their favored calling sites, e.g., trees dying or suitable nesting micro-habitats may fluctuate inter-annually, resulting in a shift in activity levels to different areas of the territory.

Population Status

Numbers

Conservative estimates for the global population suggest 20,000–25,000 individuals, but confidence in these estimates is low (32, 33). The western population is the largest, with the most recent estimates ranging from 20,000 to 43,000 individuals (32). The smaller eastern population was estimated at 760 individuals (23). This estimate is likely to be a gross underestimation, as subsequent surveys have shown the species is very common in rural farmland, a habitat type not included in that study.

Trends

The present global population trend for the species is unknown but appears to be stable, possibly even increasing (32, 33). In Botswana, a survey conducted in 2007/2008 showed a slight increase in numbers compared to a 1992/1993 survey using the same protocol (32). SABAP2 data (commenced 1 July 2007; last accessed 24 January 2023) also showed a greater reporting rate for both populations over most of the species range compared to SABAP1 data (1987–1992) (see Southern African Bird Atlas Project 2). However, despite a greater reporting rate for the western population in South Africa during SABAP2 compared to SABAP1, the western population in South Africa appears to have experienced a 73% reduction in the species' extent of occurrence (39), mainly due to the absence of records in the Free State during SABAP2 (see Historical Changes to the Distribution). SABAP2 data for the population on the Polokwane Plateau showed an increase in both the reporting rate and the range of the eastern population. However, the species is sensitive to changes in habitat structure, and numbers can decline rapidly if the habitat becomes unsuitable (41). In the Polokwane Game Reserve, a former stronghold of this population, numbers declined from an estimated 120 mature individuals in 2005 (23) to less than 30 in 2021 (DE, unpublished data).

Population Regulation

Short-clawed Lark is sensitive to soil-type, habitat structure associated with bush encroachment, the presence and density of tall trees and grasses, and an increase in basal cover such as when fire, grazing, and browsing are withheld (31, 41, 43). Within its distribution, it is often associated with subsistence agricultural areas and the edges of rural villages where wood harvesting, overgrazing, and livestock browsing effectively create and maintain their preferred habitat (32). The species generally avoids commercial agricultural farms where grazing is managed, and natural habitat is cleared for crop farming or grass pastures (39). The interplay of the level of grazing pressure and climatological cycles such as droughts or years of above-average rainfall may influence habitat availability on a local scale, expanding in years of drought and decreasing in wet years. Predation and other causes of nest failure, e.g., trampling and flooding, also influence reproductive success but are likely to be less important than the factors discussed above (see Measures of Breeding Activity).

Recommended Citation

Engelbrecht, G. D. (2023). Short-clawed Lark (Certhilauda chuana), version 2.0. In Birds of the World (D. G. Allan, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.shclar1.02