A Stone-built Nest 293 
pairs have taken to nesting in the weep-holes of the tunnels of the 
railway in the Ronda Mountains. From one of these weep-holes 
over 8 ft. from the ground I took a collection of stones, some 
being water-worn pebbles obviously brought from the bed of the 
gorge some 30 ft. below the railway line. The largest of these 
weighed 23 oz. 
