Conceptualisation was jointly developed by C.B., U.L., K.R. and S.W. Initial draft was written jointly by U.L., K.R. and S.W.. V.W. provided support for the preparation of data collection and data analysis. O.W. and R.F. did the first revision. U.L., K.R., S.W., V.W., S.B. and A.W. did the second revision. R.F., C.B., A.C., A.J., O.W., V.W., A.W. and S.B. did further revisions.  U.L., K.R. and S.W. did field work, C.B., R.F, A.C. and O.W. supported field work and data collection on La Palma with advises. K.R. and S.W. were responsible for data curation; U.L. and S.W. prepared maps. All authors revised the final manuscript. Photos were taken by S.W. and K.R.