Habitat selection in the last Swiss Ortolan Bunting population: final lessons before extinction

The Ortolan Bunting Emberiza hortulana has suffered a general decline across much of Western Europe in recent decades. In Switzerland, only one population remains in sub-Mediterranean shrub-steppe on the south-facing slopes of the Rhone Valley (Valais). We aimed to collect data on foraging ecology of the last Swiss Ortolan Buntings during reproduction. All males showed a disproportionate use of conventional maize fields that had been treated with herbicides, while also exhibiting an avoidance of meadows and riparian vegatation. The observed patterns of habitat use may be driven by unavailability of optimal foraging habitat, with birds being forced to use the best of a poor set of options. Structurally, it was shown that birds foraged in areas with a high proportion of bare ground, as well as moderately dense overhead vegatation. These areas did not support higher arthropod abundance, suggesting that food accessibility rather than food abundance dictated habitat selection.

Authors: Menz MHM et al. (2009) Ardea 97(3): 323-333
http://infonet.vogelwarte.ch/upload/93378383.pdf