Furrer, R., Schaub, M., Bossert, A., Isler, R., Jenny, H., Jonas, T., … Jenni, L. (2016). Variable decline of Alpine Rock Ptarmigan (Logopus muta helvetica) in Switzerland between regions and sites. Journal für Ornithologie, 157(3), 787-796. https://doi.org/10.1007/s10336-016-1324-8