Supplementary material for "Habitat preferences of the Ortolan bunting (Emberiza hortulana) in its prime wintering grounds, the cereal-dominated Ethiopian Highlands"

Abstract

Agricultural intensification and land-use changes are major factors impacting farmland biodiversity. The Ortolan Bunting Emberiza hortulana is the long-distance trans-Saharan migratory passerine that has undergone the most dramatic decline among all European farmland birds. Factors responsible for this decline may originate from the breeding grounds, migration stopovers and/or overwintering quarters. Very little is known about conditions on winter grounds, but a recent study has highlighted the utmost importance of the traditionally-managed agroecosystems in the Ethiopian Highlands as a key wintering area, apparently harbouring as much as 90% of the Ortolan Bunting’s world population. Using radiotracking and line transect surveys, this study aimed to provide fine-grained information about species-habitat relationships in the Ortolan Bunting’s overwintering quarters. Our results showed the importance, at the landscape scale, of small-scale agriculture, notably of traditionally-managed, cereal-dominated fields interspersed with semi-natural structures. At a foraging-site scale, on the other hand, patches of bare ground in combination with high amounts of post-harvesting stubble represented key habitat features. Stubbles provide an essential food resource, whereas bare ground promotes ground foraging by enhancing food accessibility. The maintenance of a traditional agricultural economy will be essential to maintain the habitat potential for the Ortolan Buntings overwintering in the Ethiopian Highlands, and will be instrumental in preserving its world population from further decline.