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

The centre–periphery hypothesis predicts that habitat suitability will decrease at the edge of a species' range, a pattern often questioned by empirical data. Here we explore if habitat suitability decreases southwards and shapes the abundance distribution of rear edge populations of forest birds within the restricted geographical setting of the south-western Palaearctic. We also test if birds endemic to the area fit more poorly to the latitudinal decrease of habitat suitability due to the putative effect of adaptations to regional conditions. Location: North-western Africa (Morocco) Time period: Present day Major taxa studied: Passerines (11 species) Methods: Bird occurrences were used to model species distribution and line transects were used to estimate bird abundance. Occurrence probabilities provided by species distribution models were used to display the spatial patterning of habitat suitability. Habitat suitability was employed to predict abundance after controlling for the effec...