Elevation, climate and bird abundance distribution along the latitudinal gradient defined by the sampling localities in Fig 1B.

A) Elevation, B) temperature, C) precipitation seasonality, D) precipitation. Climate variables are averages provided by the WorldClim-Global Climate Data facility (http://www.worldclim.org) for the 1950–2000 and 2050–2070 periods (see text). The abundances along the gradient of the meadow pipit (E) and the chiffchaff (F) are also reported.