488 



A HISTORY OF 



CHAPTER LXXXVII. 



OF RAPACIOUS BIRDS OF THE OWL KIND, THAT PREY BY NIGHT. 



HITHERTO we have been describing a 

 tribe of animals who, though plunderers 

 among their fellows of the air, yet wage war 

 boldly in the face of day. We now come to 

 a race equally cruel and rapacious ; but who 

 add to their savage disposition, the further 

 reproach of treachery, and carry on all their 

 depredations by night. 



All birds of the owl kind may be consider- 

 ed as nocturnal robbers, who, unfitted for 

 taking their prey while it is light, surprise it 

 at those hours of rest, when the tribes of na- 

 ture are in the least expectation of an ene- 

 my. Thus there seems no link in nature's 

 chain broken: no where a dead inactive re- 

 pose ; but every place, every season, every 

 hour of the day and night, is bustlifig with 

 life, and furnishing instances of industry, self- 

 defence, and invasion. 



All birds of the owl kind have one com- 

 mon mark, by which they are distinguished 

 from others; their eyes are formed for seeing 

 better in the dusk than in the broad glare 

 of sun- shine. As in the eyes of tigers and 

 and cats, that are formed for a life of noctur- 

 nal depredation, there is a quality in the re- 

 tina that takes in the rays of light so copious- 

 ly as to permit their seeing in places almost 

 quite dark ; so in these birds there is the 

 same conformation of that organ, and though, 

 like us, they cannot see in a total exclusion 

 of light, yet they are sufficiently quick-sighted, 

 at times when we remain in total obscurity. 

 In the eyes of all animals, nature hath made 

 a complete provision, either to shut out too 

 much light, or to admit a sufficiency, by the 

 contraction and dilatation of the pupil. In 

 these birds the pupil is capable of opening 

 very wide, or shutting very close: by con- 

 tracting the pupil, the brighter light of the 

 day, which would act too powerfully upon 

 the sensibility of the retina, is excluded; by 

 dilating the pupil, the animal takes in the 

 more faint rays of the night, and thereby is 



enabled to spy its prey, and catch it with 

 greater facility in the dark. Beside this, 

 there is an irradiation on the back of the eye, 

 and the very iris itself has a faculty of reflect- 

 ing the rays of light, so as to assist vision in 

 the gloomy places where these birds are 

 found to frequent. 



But though owls are dazzled by too bright 

 a day-light, yet they do not see best in the 

 darkest nights, as some have been apt to 

 imagine. It is in the dusk of the evening, or 

 the gray of the morning, that they are best 

 fitted for seeing, at those seasons when there 

 is neither too much light, nor too little. It 

 is then that they issue from their retreats, to 

 hunt or to surprise their prey, which is usu- 

 ally attended with great success: it is then 

 that they find all other birds asleep, or pre- 

 paring for repose, and they have only to seize 

 the most unguarded. 



The nights when the moon shines are the 

 times of their most successful plunder; for 

 when it is wholly dark, they are less qualified 

 for seeing and pursuing their prey : except, 

 therefore, by moonlight, they contract the 

 hours of their chace; and if they come out 

 at the approach of dusk in the evening, they 

 return before it is totally dark, and then rise 

 by twilight the next morning to pursue their 

 game, and to return in like manner, before 

 the broad day-light begins to dazzle them 

 with its splendour. 



Yet the faculty of seeing in the night, or of 

 being entirely dazzled by day, is not alike in 

 every species of these nocturnal birds: some 

 see by night better than others; and some 

 are so little dazzled by day-light, that they 

 perceive their enemies, and avoid them. The 

 common White or Barn Owl, for instance, 

 sees with such exquisite acuteness in the 

 dark, that though the barn has been shut at 

 night, and the light thus totally excluded, yet 

 it perceives the smallest mouse that peeps 

 from its hole: on the contrary, the Brown 



