The opposite side of the pass is dominated by the picturesque pile called the Picacho del Aljibe, a conical peak that towers in tiers of crags above the adjoining sierras not unlike a gigantic Arthur's Seat over the Salisbury Crags. Our own side was rather a chaotic jumble of detached monoliths than cliffs proper, and by clambering over these we reached in one morning sixteen vultures' nests, the easiest of access we ever struck. They were mostly very slight affairs, bare rock often protruding through the scanty structure; though, where necessary, a broad platform of sticks was provided--as sketched. The poults (only one in each nest) were now as big as guinea-fowls, with brown feathers sprouting through the white down. These eyries, albeit slightly malodorous, are always strictly clean, since vultures feed their young by disgorging half-digested food from their own crops, and we watched this not-pleasing operation being performed within some eighty yards' distance; hence there is no carrion or putrefying matter lying about, as is the case with the neophron and lammergeyer. [Illustration: GRIFFON VULTURE FEEDING YOUNG--PUERTA DE PALOMAS, APRIL 10, 1910.] These eyries were situate on three great outstanding stacks of rock, and during the scramble we came face to face with a pair of eagle-owls solemnly dreaming away the hours in the recesses of a cavern, though no sign of a nest was discovered. The caves were shared by crag-martins, whose swallow-like nests were fixed under the roof, usually just beyond reach. Their eggs are white, flecked with grey. On May 18 we obtained here a nest of the rock-thrush with five beautiful greenish-blue eggs. It was built in a cranny of the crags.