’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 phalaenae 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.