I cannot answer better than by giving Humboldt’s account of the Cave of Caripe, on the Spanish main hard by, where he discovered them, or rather described them to civilised Europe, for the first time:—

‘The Cueva del Guacharo is pierced in the vertical profile of a rock. The entrance is towards the south, and forms a vault eighty feet broad and seventy-two feet high. This elevation is but a fifth less than the colonnade of the Louvre. The rock that surmounts the grotto is covered with trees of gigantic height. The Mammee-tree and the Genipa, with large and shining leaves, raise their branches vertically towards the sky; while those of the Courbaril and the Erythrina form, as they extend themselves, a thick vault of verdure. Plants of the family of Pothos with succulent stems, Oxalises, and Orchideæ of a singular construction, rise in the driest clefts of the rocks; while creeping plants waving in the winds are interwoven in festoons before the opening of the cavern. We distinguished in these festoons a Bignonia of a violet blue, the purple Dolichos, and, for the first time, that magnificent Solandra, the orange flower of which has a fleshy tube more than four inches long. The entrances of grottoes, like the view of cascades, derive their principal charm from the situation, more or less majestic, in which they are placed, and which in some sort determines the character of the landscape. What a contrast between the Cueva of Caripe and those caverns of the north crowned with oaks and gloomy larch-trees!

‘But this luxury of vegetation embellishes not only the outside of the vault, it appears even in the vestibule of the grotto. We saw with astonishment plantain-leaved Heliconias, eighteen feet high, the Praga palm-trees, and arborescent Arums follow the banks of the river, even to those subterranean places. The vegetation continues in the Cave of Caripe, as in the deep crevices of the Andes, half excluded from the light of day; and does not disappear till, advancing in the interior, we reach thirty or forty paces from the entrance. . . .

‘The Guacharo quits the cavern at nightfall, especially when the moon shines. It is almost the only frugivorous nocturnal bird that is yet known; the conformation of its feet sufficiently shows that it does not hunt like our owls. It feeds on very hard fruits, as the Nutcracker and the Pyrrhocorax. The latter nestles also in clefts of rocks, and is known under the name of night-crow. The Indians assured us that the Guacharo does not pursue either the lamellicorn insects, or those phalænæ which serve as food to the goat-suckers. It is sufficient to compare the beaks of the Guacharo and goat-sucker to conjecture how much their manners must differ. It is difficult to form an idea of the horrible noise occasioned by thousands of these birds in the dark part of the cavern, and which can only be compared to the croaking of our crows, which in the pine forests of the north live in society, and construct their nests upon trees the tops of which touch each other. The shrill and piercing cries of the Guacharos strike upon the vaults of the rocks, and are repeated by the echo in the depth of the cavern. The Indians showed us the nests of these birds by fixing torches to the end of a long pole. These nests were fifty or sixty feet high above our heads, in holes in the shape of funnels, with which the roof of the grotto is pierced like a sieve. The noise increased as we advanced, and the birds were affrighted by the light of the torches of copal. When this noise ceased a few minutes around us we heard at a distance the plaintive cries of the birds roosting in other ramifications of the cavern. It seemed as if these bands answered each other alternately.

‘The Indians enter into the Cueva del Guacharo once a year, near midsummer, armed with poles, by means of which they destroy the greater part of the nests. At this season several thousands of birds are killed; and the old ones, as if to defend their brood, hover over the heads of the Indians, uttering terrible cries. The young, which fall to the ground, are opened on the spot. Their peritoneum is extremely loaded with fat, and a layer of fat reaches from the abdomen to the anus, forming a kind of cushion between the legs of the bird. This quantity of fat in frugivorous animals, not exposed to the light, and exerting very little muscular motion, reminds us of what has been long since observed in the fattening of geese and oxen. It is well known how favourable darkness and repose are to this process. The nocturnal birds of Europe are lean, because, instead of feeding on fruits, like the Guacharo, they live on the scanty produce of their prey. At the period which is commonly called at Caripe the “oil harvest,” the Indians build huts with palm-leaves near the entrance, and even in the porch of the cavern. Of these we still saw some remains. There, with a fire of brushwood, they melt in pots of clay the fat of the young birds just killed. This fat is known by the name of butter or oil (manteca or aceite) of the Guacharo. It is half liquid, transparent without smell, and so pure that it may be kept above a year without becoming rancid. At the convent of Caripe no other oil is used in the kitchen of the monks but that of the cavern; and we never observed that it gave the aliments a disagreeable taste or smell.

‘Young Guacharos have been sent to the port or Cumana, and lived there several days without taking any nourishment, the seeds offered to them not suiting their taste. When the crops and gizzards of the young birds are opened in the cavern, they are found to contain all sorts of hard and dry fruits, which furnish, under the singular name of Guacharo seed (semilla del Guacharo), a very celebrated remedy against intermittent fevers. The old birds carry these seeds to their young. They are carefully collected and sent to the sick at Cariaco, and other places of the low regions, where fevers are prevalent. . . .

‘The natives connect mystic ideas with this cave, inhabited by nocturnal birds; they believe that the souls of their ancestors sojourn in the deep recesses of the cavern. “Man,” say they, “should avoid places which are enlightened neither by the sun” (Zis) “nor by the moon” (Nuna). To go and join the Guacharos is to rejoin their fathers, is to die. The magicians (piaches) and the poisoners (imorons) perform their nocturnal tricks at the entrance of the cavern, to conjure the chief of the evil spirits (ivorokiamo). Thus in every climate the first fictions of nations resemble each other, those especially which relate to two principles governing the world, the abode of souls after death, the happiness of the virtuous, and the punishment of the guilty. The most different and barbarous languages present a certain number of images which are the same, because they have their source in the nature of our intellect and our sensations. Darkness is everywhere connected with the idea of death. The Grotto of Caripe is the Tartarus of the Greeks; and the Guacharos, which hover over the rivulet, uttering plaintive cries, remind us of the Stygian birds. . . .

‘The missionaries, with all their authority, could not prevail on the Indians to penetrate farther into the cavern. As the vault grew lower, the cries of the Guacharos became more shrill. We were obliged to yield to the pusillanimity of our guides, and trace back our steps. The appearance of the cavern was indeed very uniform. We find that a bishop of St. Thomas of Guiana had gone farther than ourselves. He had measured nearly two thousand five hundred feet from the mouth to the spot where he stopped, though the cavern reached farther. The remembrance or this fact was preserved in the convent of Caripe, without the exact period being noted. The bishop had provided himself with great torches of white wax of Castille. We had torches composed only of the bark of trees and native resin. The thick smoke which issues from these torches, in a narrow subterranean passage, hurts the eyes and obstructs the respiration.

‘We followed the course of the torrent to go out of the cavern. Before our eyes were dazzled by the light of day, we saw, without the grotto, the water of the river sparkling amid the foliage of the trees that concealed it. It was like a picture placed in the distance, and to which the mouth of the cavern served as a frame. Having at length reached the entrance, and seated ourselves on the banks of the rivulet, we rested after our fatigue. We were glad to be beyond the hoarse cries of the birds, and to leave a place where darkness does not offer even the charm of silence and tranquillity. We could scarcely persuade ourselves that the name of the Grotto of Caripe had hitherto remained unknown in Europe. The Guacharos alone would have been sufficient to render it celebrated. These nocturnal birds have been nowhere yet discovered except in the mountains of Caripe and Cumanacoa.’

So much from the great master, who was not aware (never having visited Trinidad) that the Guacharo was well known there under the name of Diablotin. But his account of Caripe was fully corroborated by my host, who had gone there last year, and, by the help of the magnesium light, had penetrated farther into the cave than either the bishop or Humboldt. He had brought home also several Guacharos from the Trinidad caves, all of which died on the passage, for want, seemingly, of the oily nuts on which they feed. A live Guacharo has, as yet, never been seen in Europe; and to get one safe to the Zoological Gardens, as well as to get one or two corpses for the Cambridge Museum, was our hope—a hope still, alas! unfulfilled. A nest, however, of the Guacharo has been brought to England by my host since my departure; a round lump of mud, of the size and shape of a large cheese, with a shallow depression on the top, in which the eggs are laid. A list of the seeds found in the stomachs of Guacharos by my friend Mr. Prestoe of the Botanical Gardens, Port of Spain, will be found in an Appendix.