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The poorly known Black-rumped Buttonquail Turnix nanus has a small and fragmented regional population, estimated to be less than1 000 mature individuals, with no sub-populations likely to exceed 250 mature individuals, satisfying criterion B2. It is dependent on grasslands that have been much reduced and are under severe threat, qualifying it as regionally Endangered.
A secretive and easily overlooked species that is widespread but generally sparse in moist woodland belts, savannah and grassland in sub-Saharan Africa. Occurs from Senegal and Gambia eastwards to Uganda and western Kenya, and south through much of central Africa to northern Angola, Zambia and Malawi (Urban et al. 1986). In Zimbabwe, recorded from the south-eastern Lowveld, and also from across the Mashonaland Plateau between Harare and Marondera, where it is an itinerant and nomadic visitor, mostly in the rainy season (Irwin 1981, Allan and Colahan 1997). Status uncertain in Mozambique, and probably widely overlooked; north of the Save River considered an uncommon breeding summer migrant to moist grasslands, and fairly numerous on low-lying plains from Beira northwards (Parker 2005); in southern Mozambique recorded from a few scattered localities in summer (Parker 1999).
Within the region, the Black-rumped Buttonquail's occurrence is generally patchy and erratic, but its secretive behaviour, cryptic plumage and imperfectly known movement patterns ensure that it is widely under-recorded, or misidentified (Christian 2004). Based on limited atlas and specimen data, there appears to be two apparently isolated centres of distribution: south-eastern Mpumalanga, Swaziland and northern KwaZulu-Natal (contiguous with populations in southern Mozambique); and southern KwaZulu-Natal and the adjacent Eastern Cape, where it is probably more widespread than current records indicate, especially in the former Transkei (Quickelberge 1989). It is considered a rare, but probably breeding resident in Swaziland (Parker 1994). The Black-rumped Buttonquail was not listed for Lesotho by Bonde (1993), but may occasionally occur in small numbers, especially in the western lowlands.
The relatively large EoO but small AoO reflects the localised and fragmented range of this species, which was estimated at less than 1 750 km2 by Taylor (2000). Recent SABAP2 data suggest an AoO of c. 5 200 km2, although only a small percentage of this area constitutes suitable habitat and the estimate provided by Taylor (2000) is more likely. The overall distribution is reminiscent of that of the Short-tailed Pipit Anthus brachyurus, and the two species ostensibly have similar ecological requirements and movement patterns, and often occur in close proximity. Bearing this in mind, searches should be made for Black-rumped Buttonquails in areas where the pipit occurs, including newly discovered locations in Eastern Cape and on the outskirts of Gauteng. Indeed, both species were recently discovered in large numbers near Verena, western Mpumalanga (well outside of their known ranges), where they were suspected to be breeding.
The global population size is unknown (BirdLife International 2014). Brooke (1984) classified this species as one of the five most threatened birds in South Africa, and speculated that it may now be mostly a vagrant that no longer breeds in the region. Based on estimates in Barnes (1998), a total of 212-584 birds possibly occurred in 13 IBAs in eastern South Africa, while Parker (1994) estimated a population of 70 birds in Swaziland. It may be locally common in optimal breeding habitat, and Christian (2004) reported that between November and February the hooting of female Black-rumped Buttonquails was heard almost continually at a breeding site near Cato Ridge, KwaZulu-Natal, with at least five hooting females (plus an unknown number of males) present in the small study area, and probably many more in the extensive surrounding habitat. Likewise, at least four birds were found in 8 ha at Vernon Crookes Nature Reserve in southern KwaZulu-Natal (Christian 2004). Taylor (2000) suggested the total regional population may be in the order of 1 000 birds, but confidence in this estimate is low given that this species is so easily overlooked. No up to date population estimates are available although the regional population is almost certainly less than 1 000 mature individuals.
Globally, the species is suspected to be in decline owing to on-going habitat destruction and unsustainable levels of exploitation (BirdLife International 2014). The regional population is likewise thought to have undergone a severe and continuing decline owing to deterioration and destruction of its grassland habitat (Taylor 2000). Evidence suggests that the species was formerly much more widespread, although the high potential for confusion with the numerous Common Buttonquail, or any of the Coturnix quails makes the authenticity of some older records questionable. Brooke (1984) mentioned that this species was probably formerly a breeding summer visitor to plateaus of Free State province, and plotted a record from near Excelsior. Its occurrence in that province was not confirmed by subsequent atlas fieldwork (Earlé and Grobler 1987, Allan and Colahan 1997), but there is a recent SABAP2 record from the Golden Gate Highlands National Park area; further fieldwork is likely to reveal this buttonquail's presence in other parts of the eastern Free State. Likewise, its range in the former Transvaal appears to have contracted significantly. Tarboton et al. (1987) mention a specimen record as far north as Giyani, Limpopo and cite post-1979 sight records from Tzaneen and Serala (Wolkberg) in Limpopo, and Kangwane, Sabie, Malelane and Lower Sabie in Mpumalanga, all areas where this species has not been recorded recently. In KwaZulu-Natal there are historical breeding records from areas where suitable habitat no longer exists, e.g. Hillcrest (Tarboton 2001) and Pinetown (Clancey 1964); such records, together with the range outlined by Brooke (1984) suggest that the currently separated northern and southern populations were previously linked, and that the species also occurred further south in Eastern Cape. The regional population is thought to be in decline although the rate of decline is unknown. Confidence in this trend estimate is low.
The threats faced by this species are shared with many other grassland specialists, and all threats contribute to deterioration and destruction of its grassland habitat: commercial afforestation, crop agriculture, stock farming and expanding rural and urban settlements (Allan and Colahan 1997), and on a local scale, mining operations and infrastructure development. Overly frequent burning is also considered a threat, but fires are probably an essential element to maintaining this species' preferred short and open-structured grassland habitat, and preventing development of a dense moribund layer at ground-level; biennial burning cycles may be most beneficial, but further research is needed.
The extent and quality of suitable habitat is likely to be reduced by infestation of forbs and exotic pioneer plants, trampling by livestock, grazing practices, agricultural activities, soil erosion and edge effects of increasing habitat fragmentation; the latter may influence local dispersal ability as well. The potential effects of drought and climate change should also be investigated. At sites near human settlements, localised threats may include disturbance from pedestrians, dogs, and ‘quad' bikes (Christian 2004), collisions with illuminated windows when flying at night, and predation by domestic and feral cats. It is unknown whether wing-shooting poses a significant threat, but there is a strong possibility that this species may be shot inadvertently while hunting the superficially similar Common Quail Coturnix coturnix, a highly prized quarry for both social and commercial wing-shooters in summer (Little 2012). The very similar Common Buttonquail may also be hunted occasionally.
In the globally Near Threatened Black-breasted Buttonquail T. melanogaster of eastern Australia, females are outnumbered by males and extirpation of even a small proportion of the population may thus lead to disproportionately skewed sex ratios and make populations vulnerable to genetic bottlenecks (Mathieson and Smith 2009); sex ratios have not been researched in the Black-rumped Buttonquail but may likewise be favoured to males given the presumed polyandrous breeding system (Urban et al. 1986, Tarboton 2001). In captivity the related Common Buttonquail exhibits remarkably high reproductive potential, with wild populations presumed to be curtailed by high mortality rate, lack of suitable climatic conditions for breeding, and shortage of potential mates of one sex (Urban et al. 1986). If similar factors counterbalance Black-rumped Buttonquail fecundity, significant population crashes may occur if total regional populations fall below critical levels.
No species-specific conservation measures focusing on the Black-rumped Buttonquail are currently underway.
Brooke (1984), echoed by Allan and Colahan (1997) and Taylor (2000), urged that a survey is required to establish the status, distribution and habitat preferences before an adequate conservation programme can be planned and implemented (2013), and this is still the case. A national species recovery plan should be drawn up (see e.g. Mathieson and Smith 2009), with the involvement of conservation authorities, public-interest groups and land-owners, to: 1) investigate biological, ecological and demographic questions, 2) map and survey the historic, current and potential range, 3) develop an effective land-management strategy, 4) protect, expand and rehabilitate suitable habitat, 5) reduce or eliminate threats to the species and its habitat, and 6) establish a long-term monitoring programme.
Conserving a nomadic, erratic and wide-ranging species such as the Black-rumped Buttonquail appears to be, is challenging, and will require protection and effective management of large tracts of wilderness and smaller sites where breeding occurs, both in reserves and on private land. Two major key sites are probably uKhahlamba-Drakensberg Park (SA IBA064) and iSimangaliso Wetland Park (SA IBA058), with the latter considered very important for the conservation of the species (Combrink and Kyle 2006). Taylor (2000) estimated that 20-56% of the regional population may occur in fully or partially protected IBAs. A re-assessment of the management practices and status of these IBAs should be executed.
Although this poses a considerable challenge, population surveys and habitat analyses should be prioritised, in order to re-assess the conservation status, prioritise sites for conservation, and identify suitable research locations. Furthermore, birdwatchers and land-owners should be encouraged to report any ad hoc sightings with supporting details to BirdLife South Africa and SABAP2.
In addition to conservation and recovery efforts of existing populations, a re-introduction programme is a viable option, as has been proposed for the Common Buttonquail in southern Europe (Pertoldi et al. 2006), which has been virtually extirpated from the Mediterranean region (Expósito et al. 2011). The reproductive potential of Common Buttonquails is high in captivity (Flieg 1973, Wintle 1975) and there are established husbandry practices (Spenkelink-Van Schaik 1984); captive-breeding potential is probably good for the Black-rumped Buttonquail as well (Brooke 1984).
* Collate in a database all known historical and contemporary occurrence and breeding records, based on atlasing data, sight records, published literature and museum specimens; critically assess and verify the authenticity of all records.
* Using this database, map the historic and current range of the species and identify ecological requirements and factors limiting the distribution.
* Develop a predictive model of the species' distribution, incorporating a variety of environmental variables and current land-use data, in order to identify key zones for conservation and areas which potentially hold suitable habitat to support the species.
* Develop an effective methodology for surveying and monitoring buttonquails, and survey potential sites where the species is known to occur, occurred historically, or potentially occurs but has not yet been recorded.
* Evaluate threats to the species and its habitat, and develop and implement an effective management plan.