This paper studies the factors affecting passerine (Order Passeriformes) species richness in the Western Maghreb, a region at the southwestern border of the Palearctic reputed as a primary wintering ground for many common European birds. The effect of productivity, temperature, landscape structure and geographical location on bird richness was explored at 220 localities across Morocco. The models resulting from multivariate analyses supported the effects of productivity, temperature and landscape cover on bird richness, with higher numbers of species occurring in warm farmlands of the northwest. The most suitable areas for birds avoided the cold and arid expanses of the Atlas Mountains and the Sahara and overlapped with the most human-impacted sectors. Within these areas, we detected an interspersed distribution of sectors of high bird richness and low human incidence. These sectors can be used as priority targets for conservation programmes of common birds during the winter.