Habitat modelling reveals extreme habitat fragmentation in the endangered and declining Asir Magpie, Pica asirensis, Saudi Arabia’s only endemic bird (Aves: Passeriformes)

Abstract

The endangered Asir Magpie Pica asirensis formerly occurred in alpine habitat across Saudi Arabia’s Asir Mountains but is now restricted to small patches of remnant forest within a 37-km strip of highlands. Perhaps only 100 pairs remain and this tiny population appears to be declining, though the causes of its decline are unknown. We mined published presence/absence data to develop a fuzzy logic habitat model. The model considered six variables that correlate with Asir Magpie presence: elevation, aspect, forested areas, drainage systems, and major urban areas. Our model reveals that only 80 km2 of prime quality habitat remains across 11 fragmented patches. We tested the model using 38 GPS locations of Asir Magpies from independent birdwatchers. In total, 35/38 magpies were located within the modelled habitat. We suggest that the Asir Magpie may be suffering from limited dispersal between isolated high quality habitat fragments, which could be leading to genetically depauperate subpopulations, thereby enabling an extinction vortex. It may also be suffering from habitat loss through development and construction, habitat degradation through climate change, unregulated grazing, overharvesting of wood, and over-consumption of food scraps. Corrective actions are urgently needed to save this rare and nationally endemic species.