THE FERN-OWL. 261 



With all these united powers, swift and silent too in flight 

 as it is, no wonder that this bird makes such havoc amongst 

 the, to us nearly invisible, multitudes that people the silent 

 air on a summer's night. At twilight, it may sometimes be 

 seen at work, flitting about, hovering now over one spot, 

 then over another, occasionally dropping or tumbling over, 

 as if shot ; this is the moment, when having seized a moth, 

 the bird reaches it to its mouth, and loses its balance, when 

 again rising, it glides away like a ghost, till lost in shade. 

 We have but one species visiting England, but in foreign 

 countries there are many. In South America, particularly, 

 they abound : the curious retreats of one species of these 

 birds are thus described by the celebrated traveller, M. de 

 Humboldt, who visited a dark chasm in the rocks called the 

 cavern of Guacharo, frequented by a species (Caprimulgus 

 steatornis) whose young were caught to furnish oil : 



"A frightful noise, made by these birds, issued from the dark 

 recesses of the cavern ; their shrill and piercing tones rever- 

 berated from the arched roofs, and re-echoed from the depths of 

 the cave. The Indians, by fixing torches to the end of a long 

 pole, pointed out their nests, arranged in funnel-shaped holes, 

 with which the whole roof of the grotto was riddled. As the 

 travellers advanced, the noise increased, the flare of the torches 

 alarmingthe birds still more. When it ceased for afew minutes , 

 distinct moans were heard from other remote branches of the 

 cavern, the alternate responses of other flocks of these birds. The 

 Indians, every year about Midsummer, descend into the cave, 

 furnished with poles, for the purpose of destroying the nests. 

 At this time many thousands of birds are killed, and the old 

 ones, as if to protect their broods, hover over the heads of the 

 Indians, uttering the most dreadful shrieks. The young that 

 fall to the ground are immediately ripped open, to procure a 

 sort of unctuous or fatty substance with which they are then 

 loaded. At this period, which is commonly termed the oil- 

 harvest, the Indians construct little habitations of palm- 

 leaves, close to the opening, and even in the mouth of the 

 cavern. Here the grease of the young birds just killed 

 is melted over a fire of dry sticks, and run into pots of white, 

 clay. This grease, known by the name of Guacharo butter 



