Justification of Red List Category
This newly-lumped species is listed as Critically Endangered because it has an extremely small range, it is only confirmed to occur at two locations and its range size is decreasing. Remaining habitat is rapidly being degraded by agricultural cultivation and grazing, and the number of mature individuals is decreasing (the total population is now believed to number fewer than 250 mature individuals). A potentially skewed sex ratio may mean the effective population size is even smaller, and the species is projected to undergo a reduction of more than 80% in just three generations. The species has apparently been lost from its type locality in Somalia owing to intense land-use change.
The total population is now likely to number fewer than 250 individuals, with fewer than 50 individuals in each of the two subpopulations.
Both the populations on the Liben Plain and at Jijiga are thought to be declining. On the Liben Plain the population is suspected to be declining because the species is restricted to grassland in the calcareous plateau east and south of Negele (L. Borghesio in litt. 2005) which decreased in area by about 30% between 1973 and 2002, and is being rapidly encroached by shrubs, agriculture and homesteads. The remaining area is being rapidly degraded due to overgrazing by livestock. Over 15% of remaining habitat on the Liben plain was lost in a single year, suggesting that the rate of decline may now be higher (P. F. Donald in litt. 2012). Habitat loss is expected to take place at a similar rate at Jijiga given that cultivation in the area is apparently ongoing (Spottiswoode et al. 2013). The total population can therefore be projected to undergo a reduction of greater than 80% over the period of three generations and greater than 25% in one generation.
The species occupies mid-altitude grassland in Ethiopia and Somalia. However severe land-use change at its Somalian type locality means that it probably no longer occurs there (Spottiswoode et al. 2013). The species was for some time known only from two specimens collected at adjacent sites near Negele in the former Sidamo province (now Guji Zone), southern Ethiopia, in May 1968 and April 1974. Since 1994 there have been subsequent sightings of small numbers (<10 on each occasion) in the Negele area. Analysis of these locations on satellite images and recent fieldwork suggests that the species is restricted to a very specific habitat (tall-grass prairie) in the calcareous plateau east and south of Negele (L. Borghesio in litt. 2005, Donald et al. 2010). Between 1973 and 2002 the area of tall-grass prairie decreased by about 30%, and in 2003 much of it was being rapidly encroached by agriculture and shrubs (Acacia drepanolobiumand others) that are probably favoured by excessive grazing pressure and the suppression of seasonal fires (L. Borghesio in litt. 2005). Remaining grassland is being heavily degraded by overgrazing (Spottiswoode et al. 2009). By 2007-2008 it appeared to be restricted to a single grassland patch 30-36 km2 in area, and the global population was estimated at just 90-256 mature individuals, with the effective population size perhaps even smaller owing to a potentially skewed sex ratio caused by predation of females on the nest (Spottiswoode et al.2009). Results of survey work to date indicate that the species has fewer than 100 territories (the number of pairs is unknown: females seem to be much scarcer than males, so many territories may be held by bachelors) (Donald et al. 2010, N. Collar in litt. 2011). Compared with a survey in June 2007, fieldwork in May 2009 recorded a decline of 40% in the number of birds present along repeated transects and a contraction of 38% in the area of the Liben Plain occupied by the species (Donald et al. 2010), with a further decrease to c.25% km2 in 2011, a 44% reduction on that recorded in 2007 (Abdu 2012).
H. a. archeri was historically known from a very restricted area, the Wajale plain, from Jifa Medir to Ban Wujaleh, west of Hargeisa in north-west Somalia, along the Ethiopian frontier (Spottiswoode et al. 2013). Between 1970 and 2008 fifteen visits to the Somalian type locality or areas adjacent to it failed to find the species. In 2010, a search for the species in the Wajale Plains and surrounding area in Somalia was unsuccessful and the habitat there was found to have changed dramatically due to grazing and mechanised agriculture, with no natural grassland thought to remain (A. Jama in litt. 2010, Spottiswoode et al. 2013, Mills et al. 2015). Predictive modelling based on the characteristics of the Liben Plain suggested that apart from a smaller and highly politically unstable area c.500 km to the north-east near the Somalian border there is no other suitable habitat for the species within the Horn of Africa (Donald et al. 2010). In 2011 a survey in grassland east of Jijiga in north-east Ethiopia (close to the area that the predictive model suggested [Donald et al, 2010]) found more than 10 individuals in heavily degraded grassland (Spottiswoode et al. 2013). The area of suitable grassland at Jijiga is apparently very limited (maximum estimated extent of 20 x 12 km), with >80% grass cover under 5 cm in height (Spottiswoode et al. 2013). Niche modelling suggests that apart from a few small scattered sites in central Ethiopia, the Liben Plain and Jijiga are the only occupied sites for the species (Spottiswoode et al. 2013).
In Ethiopia all reliable records appear to fall within or near grassland areas (L. Borghesio in litt. 2005). A possible sighting in 1971 in dense Acacia woodland seems doubtful (L. Borghesio in litt. 2005). It has been found to avoid woody vegetation, very short grass and bare ground (all symptomatic of degraded rangelands), and to favour a grass sward of intermediate height (5-15 cm) (Spottiswoode et al. 2009). It has never been recorded from croplands (Spottiswoode et al. 2009). The nest is a grass bowl on the ground (Collar et al. 2008). In its Somalian range the species is known from an area with 300-400 mm rainfall per year. Habitat at its two known sites varies: one is open grassland and the other fairly open, rocky country with scattered and sparse bush and limited grass cover (Ash and Miskell 1998). It avoids open spaces, creeping through grass cover, and flies reluctantly (Ash and Miskell 1998). Its diet is unknown. Nests have been observed in June, and clutch-size is three (Ash and Miskell 1998).
The Negele plateau is being degraded by human activities, leading to loss of grassland habitat and encroachment of bush, mainly Acacia drepanolobium (Coppock 1994, M. Wondafrash in litt. 2005). Shrub encroachment has probably been exacerbated by the fire suppression that has been enforced in the area since the 1980s (L. Borghesio in litt. 2007). Refugees from drought-stricken and tribal conflict areas are augmenting the dense local human population, and nomadic pastoralism is giving way to permanent cultivation, which is the principal threat to the species (M. Wondafrash in litt. 2005). A watering point has been developed in the core of the species's range, leading to concentrations of livestock and consequent disturbance, overgrazing and trampling (M. Wondafrash in litt. 2005). Remaining grassland had become even more degraded between the 2007 and 2008 surveys, leaving no real cover for the species, and potentially leading to high predation of females on the nest, reducing breeding success to zero and further lowering the effective population size (N. J. Collar in litt. 2009). Further fieldwork in 2009 confirmed that habitat degradation was continuing, probably due to overgrazing, and that grassland was still being lost to cultivation (Donald et al. 2010). Between 2010 and 2011, around a third of the grassland on the northern side of the Liben Plain was lost to agriculture (P. F. Donald in litt. 2012). The operation of a military training area (near the Bogol Manya crossroads) was previously listed as a potential threat (I. Sinclair in litt. 1999), but this had been abandoned by July 2005 (L. Fishpool in litt. 2006). Drought may compound these threats, and rising temperatures may pose a longer-term threat to the survival of the species.
The original grassland site in Somalia was settled and cultivated by refugees (J. S. Ash in litt. 1999), resulting in the disappearance of the tussocky perennial grasses described as the species's habitat in 1922 (J. Miskell in litt. 2004). The refugees left over two decades ago, but the area is now more intensively farmed and grazed than ever before (J. Miskell in litt. 2007, 2008, A. Jama in litt. 2010). People have staked out land claims on the plain, and these plots are being surveyed and registered, and the owners issued with title deeds (J. Miskell in litt. 2007, 2008). Habitat has also been lost and degraded through the establishment of settlements, fires and invasion of alien shrubs and herbs (A. Jama in litt. 2010, Mills et al. 2015).
Conservation and Research Actions Underway
A three-year Darwin project commenced in 2015 (Anon. 2015). The project aims to create approximately 1,000 ha of grazing reserves on the Liben plain, managed by the pastoralist community and capable of supporting 10,000 pastoralists during the dry season (Ward-Francis 2015). Grassland will be restored in these reserves which is expected to increase the area of suitable habitat for the species. Through this project, awareness of the importance of protecting and restoring grassland resources for the lark as well as for pastoralist livelihoods has been increased both within the local Government and communities on the plain (A. Ward-Francis in litt. 2016). As a result, there is increasing support for these activities, and over the last few years conversion to cultivation has decreased with no new cultivation on the plains in 2016 (A. Ward-Francis in litt. 2016).
Fieldwork has been taking place since 2007 to investigate the species's status (M. Wondafrash in litt. 2007, Donald et al. 2010). A workshop in 2009 involving key stakeholders resulted in the creation of an intersectoral committee to manage the restoration of the Liben Plain, an agreement to oppose any further agricultural expansion and a willingness to work with conservation organisations to preserve pastoralism (N. J. Collar in litt. 2009), and further stakeholder meetings have taken place since. Work to clear scrub, establish non-grazing areas and prevent of further conversion of grassland on the plain is imminent, and capacity-building work training young Ethiopian nationals is ongoing (N. J. Collar in litt. 2011). The type locality for the species in Somalia was visited briefly in May 2008 but no birds were located (J. Miskell in litt. 2007, 2008). If the bird is found again in Somalia, then some land could be legally purchased and protected (J. Miskell in litt. 2007, 2008).
Conservation and Research Actions Proposed
Conduct further surveys (during the breeding season, when birds are likely to be singing and hence most conspicuous) throughout the Negele Plateau and along the Ethiopian-Somali border to establish its range and population, and determine whether there is a significantly biased sex ratio. Assess range, population size, trend and threats at Jijiga. Investigate the causes of bush encroachment at the Liben Plain population (L. Borghesio in litt. 2007). Undertake detailed socioeconomic research to identify the drivers of grassland conversion. Urgently determine the most appropriate means to safeguard areas of suitable habitat from further degradation and disturbance. Identify key areas where livestock and disturbance can be kept to a minimum and the natural fire regime is maintained. Raise awareness of the local communities and authorities of this important endemic taxon. Investigate the use of exclosures to eliminate grazing from some areas of the Liben Plain, and the possible need to employ ploughing and re-sowing of local grass species to restore suitable habitat (Donald et al. 2010). Clear encroaching Acacia thorn scrub from parts of the Liben Plain (Donald et al. 2010). Assess the possibility of using hyena dung to create small ungrazed areas with suitable nesting cover.
14 cm. Small, large-headed, short-tailed lark. Pale buff stripe down centre of crown. Upperparts look scaled. Short and thin tail. Similar spp. Singing Lark Mirafra cantillans is longer-tailed, with rusty wing-patches in flight. Voice Song is short: 3-5 melodious, clipped whistles, given in high display-flight. Hints Runs very rapidly on ground to avoid danger.
Text account compilers
Bird, J., Butchart, S., Calvert, R., Ekstrom, J., Shutes, S., Starkey, M., Symes, A., Taylor, J., Ashpole, J, Wheatley, H., Mahood, S., Harding, M., Wright, L & Westrip, J.
Borghesio, L., Collar, N., Fishpool, L., Mwangi, K., Ndang'ang'a, P., Sinclair, I., Spottiswoode, C., Wondafrash, M., Donald, P., Shirihai, H., Mulholland, G., Jama, A., Ash, J., Miskell, J. & Robertson, P.
BirdLife International (2018) Species factsheet: Heteromirafra archeri. Downloaded from http://www.birdlife.org on 19/09/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/09/2018.