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. The factors responsible for this decline may originate from the breeding grounds, migration stopovers and/or overwintering quarters. Very little is known about conditions on the species' wintering 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 world's Ortolan Bunting population. Using radiotracking and line transect surveys, this study aimed to provide fine‐grained information about species–habitat relationships in the Ortolan Bunting 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 large areas of post‐harvesting stubble represented key habitat features. Stubbles provide an essential food resource and 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.

A roadmap integrating research, policy, and actions to conserve Afro‐Palearctic migratory landbirds at a flyway scale

“…However, current studies are heavily biased toward the breeding grounds and knowledge of what is happening on the nonbreeding grounds is largely missing (Marra et al, 2015). Even studies that assessed the causes of decline of Afro-Palearctic migrants in their wintering grounds focused primarily on remote sensing techniques (Beresford et al, 2019) despite that habitat preferences of landbirds are often only detectable by quantifying finescaled habitat characteristics necessitating ground-based fieldwork in Africa (Marcacci et al, 2020(Marcacci et al, , 2022Gremion et al, 2022; see step 3 in Box 1). We therefore strongly encourage more ground-based studies in the identified geographic regions at the relevant stages of the targeted species' annual cycles in order to determine the potential threats and drivers of population declines and how to mitigate them.…”

“…The recent tracking data demonstrating that the majority of the world population overwinters in the Ethiopian Highlands calls for concerted research activities in this seemingly important habitat. Gremion et al (2022) conducted a field study in Ethiopia to investigate the habitat preferences of the overwintering Ortolan Buntings. They demonstrated the importance of small-scale agriculture with traditionally managed cereal-grain fields interspersed with seminatural habitats for the conservation of the species.…”

“…In Europe, the hunting ban on the Ortolan Bunting, following the recommendations of Jiguet et al (2019), is expected to lessen anthropogenic pressures on the western population. On the nonbreeding grounds, projects such as the Great Green Wall for the Sahara and Sahel Initiative as well as other conservation initiatives (e.g., Brown et al, 2011) are in line with the habitat requirements of the Ortolan Bunting (Gremion et al, 2022) and should result in multifunctional landscapes benefitting both the avifauna and the local communities.…”

“…Yet, the conservation potential of these tracking data is not fully exploited: we know where specific species are spending most of their annual cycle, but we still often ignore their ecological needs on their nonbreeding grounds when devising conservation measures. Indeed, only a few studies have assessed the ecological and environmental drivers responsible for the observed decline of Afro‐Palearctic migrants in their nonbreeding habitats (Beresford et al., 2019; Gremion et al., 2022). This represents a major knowledge gap and needs to be tackled urgently if we want the conservation efforts made in migratory landbirds’ breeding grounds to play a significant role in protecting Europe's most rapidly declining bird species.…”

The importance of landscape heterogeneity and vegetation structure for the conservation of the Ortolan Bunting Emberiza hortulana

“…Moreover, long-distant migrants among farmland birds are particularly threatened as they are also subject to further threats outside their breeding ranges (e.g. Bairlein 2016, Gremion et al 2022).…”