Designing a rangeland to preserve Africa’s most endangered mainland bird and a people’s way of life

Mahamued, Bruktawit Abdu (2016) Designing a rangeland to preserve Africa’s most endangered mainland bird and a people’s way of life. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

The Borana rangelands once had the highest grazing potential in East Africa and productive breed of cattle. Currently, the rangelands are severely degraded due to increase in human and cattle population, overgrazing, climate change and agricultural expansion. The Liben Plains, located 10 to 40 km from Negelle, is an area of rangeland known to be one of the last remaining stronghold of the Liben Lark (Heteromirafra archeri). The species is currently listed as Critically Endangered, mainly due to habitat degradation, and with a tiny and rapidly declining global population. Research examining the abundance and habitat preferences of the species have been ongoing since 2007. Here I present an analysis of these and additional survey data from 2007 to 2013 regarding the species population size, density and habitat associations, and track changes in the patterns of land-use, habitat loss and degradation over the last 20 years. Distance sampling line-transect surveys were used to assess the density and distribution of the species. Measurements of structural habitat characteristics were also recorded using a standardised habitat recording method in use since 2007. Spatial data analysis revealed that the Liben Plains are experiencing significant and ongoing levels of habitat loss, primarily through the conversion of grassland habitat to cereal crops farming has been evident since 1994, but has accelerated since 2000, and alarmingly, has spread to include areas of red soil grasslands that were previously believed to be unsuitable for agriculture. Density estimates from 2007 to 2013 revealed that the Liben Lark population has declined dramatically across the Plains. The species is now extremely rare, numbering no more than 1 individual per km2, and confined to just three tiny areas of ‘density hotspots’ covering an area of degraded grassland between 10km2 and 26km2 in size. Liben Larks were found to avoid areas of severe habitat degradation i.e. areas of the plains with high bare ground cover, short heavily disturbed grass, high cover of trees and invasive fennel, but preferred areas with medium to tall dense grass (least grazed areas), but patterns of habitat associations varied between differed survey seasons. Nest concealment is a large contributing factor for the survival of artificial lark nests containing artificial lark eggs, which experimental trials in this study reveal suffer extremely high nest failure rates due to predation by birds and mammals, and trampling by livestock. These factors may be restricting the Liben Lark population from breeding effectively. An integrated management system involving state, traditional and non-governmental bodies is crucial to balance grazing land for livestock and suitable habitat for the survival of the Liben Lark.