Detailed study predicts Africa’s first bird extinction looming

Sidamo lark, edging towards extinction. Photo credit Greg Davies.

March 2009. The Sidamo lark, confined to the Liben Plain grassland in southern Ethiopia, is critically endangered by bush encroachment, permanent settlement and agricultural conversion.

Its global range was previously estimated at 760 kms², but in 2007-2008 available habitat covered just 35 kms². Density estimates provided a global population estimate of 90-256 adults (possibly with a serious sex-ratio bias towards males).

The lark's habitat today consists of relativelyshort grassland, but evidence from earlier decades suggests that areas of longer grass may have been important. With its long legs, rather long thin neck and relatively feeble rectrices, the species is largely terrestrial and appears to be poorly adapted for long- distance aerial dispersal. The song, a jingling, chirping, continuous whistling, undulating in pitch, is delivered in a short, low hovering display- flight that may stimulate neighbours to do the same; a soft twi- twi- twi call (up to nine notes) may be an alarm.

In June 2007 three brownflecked whitish eggs were found in a feebly roofed grass-woven nest under a small Solanum tettense shrub, and an adult specimen was caught, sampled and released. In June 2008 overgrazing, scrub invasion and agricultural expansion were found to be threatening the Sidamo Lark with imminent extinction.

Population may be as low as 100
Prior to this study, the Sidamo lark's population size estimated by BirdLife International (2008) of 1600-2000 mature individuals represented an informed guess based on a breeding range estimate of 760 kms² and extrapolation from breeding densities of 0.6 pairs. In reality, the world range of the Sidamo lark appears to be a single grassland patch just 30-36 kms² in area, and its density to be an order of magnitude lower, with a total adult male population of only 63-179.

Sidamo lark, clining on in one tiny corner of Ethiopia. Photo credit Greg Davies.

Using the average sex ratio for Critically Endangered species suggests a total population size of 90-256. Unfortunately, even the lower value might be optimistic, given that grassland condition has further deteriorated subsequent to density estimation.

Borana pastoralists & Sidamo lark in same boat
The survival of both local Borana pastoralism and this species - mainland Africa's likeliest first avian extinction - depends on restoring seasonal patterns of grazing, resisting agricultural conversion of grasslands, reversing fire suppression policies and clearing bush.

Click here to see the full paper sidamo lark.pdf

The study was undertaken by Claire Spottiswoode of Department of Zoology, University of Cambridge, staff from the Ethiopian Wildlife and Natural History Society, BirdLife International and the University of East Anglia  and others.