Ecological and geographical marginality in rear edge populations of Palaearctic forest birds

Aim The centre–periphery hypothesis predicts that habitat suitability will decrease at the edge of a species’ range, pattern often questioned by empirical data. Here we explore if decreases southwards and shapes abundance distribution rear populations forest birds within restricted geographical setting south-western Palaearctic. We also test endemic to area fit more poorly latitudinal in due putative effect adaptations regional conditions. Location North-western Africa (Morocco). Taxon Passerines (11 species). Methods Bird occurrences were used model species line transects estimate bird abundance. Occurrence probabilities provided models display spatial patterning suitability. Habitat was employed predict after controlling for distance some source areas (tree covered large areas). classified as North African according an updated review their taxonomic status. Results decreased southwards, supporting predicted relationship between ecological marginality most species. Abundance positively correlated with negatively areas. status did not affect patterns. Main conclusions southward As these are endemic, results suggest they track gradients isolation north-western Africa. These support vulnerability isolated, peripheral large-scale environmental changes region under increasing drought temperature.