No nests were found in crevices deemed to be favourable spots, though the predilection of the genus for gloom was appreciated, but upon the exploration of a confined cave the excited flutterings of invisible birds betrayed a hitherto well-kept secret. When my eyes became accustomed to the dimness I saw that the roof of the cave (which is fairly smooth and regular with an inclination of about thirty degrees) was studded with nests. Fifty-three were placed irregularly about the middle of the roof, some in pairs, none on the walls. Some were not quite finished; twenty contained a single white egg each; none contained young. All were adherent to the stone by a semi-transparent white substance resembling isinglass, with which also the fine grass, moss, and fibre composing the nests were consolidated. The vegetable material of the first fragmentary nest (found September 17, 1908) was quite green and the gluten moist and sticky. Those now described (two months later) were dry and tough, the dimensions being 2 to 2½ inches across and about ¾ inch deep. The cave is only about 30 feet above high-water mark and the entrance the birds favour is, strange to say, averse from the sea and much obscured by leafage.
After the first fright the birds became quiet and confident. A young one flew into my half-closed hand, and I detained it for a while and it never struggled. Another tried to snoodle into the shirt-pocket of the black boy who accompanied me. Several brushed against our faces. Clouds partially obscured the sun and what with the screen of foliage and the prevailing gloom of the cave we could not always distinguish the nests. When the sun shone brightly all were plainly discernible, those with the single pearly egg being quaintly pretty. As they flitted in and out of the cave, the birds were as noiseless as butterflies save when they wheeled to avoid each other. Those which were brooding, as they flitted over the nests or clung to the edges, uttering a peculiar note hard to vocalise. To my cars it sounded as a blending of cheeping, clinking, and chattering, yet metallic, and not very unlike the hasty winding up of a clock.
One bird flew to her nest a foot or so from my face and clung to it. To test its timidity or otherwise I approached my face to within two inches, but she continued to scrutinise me even at such close quarters with charming assurance. Then I gently placed my hand over her. She struggled. but not wildly, for a few seconds and then remained passive with bright eyes glinting in the gloom. She was a dusky little creature, the primaries, the back of the head, neck, the shoulders, and tail being black, but when the wings were extended the grey fluff of the base of the tail was conspicuous. After a few minutes I put her back on the nest, and she clung, to it having no shyness or fear. I noticed that the beak was very short, the gape very large, the legs dwarfed, and the toes slender.