98 HISTOilY OF 



and dilatation of the pupil. In these birds the pupil is capable 

 of opening very wide, or shutting very close : by contracting the 

 pupil, the brighter light of the day, which would act too power- 

 fully 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. Besides this, there is an irradiation on the 

 back of the eye, and the very iris itself has a faculty of reflecting 

 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 usually attended with great success : it is then 

 that they find all other birds asleep, or preparing 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 chase; and if 

 they come out at the approach of dusk in the evening, they re- 

 turn before it is totally dark, and then rise by twilight the next 

 morning to pursue their game, and to return in like manner, be- 

 fore 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 the day, is not alike in every species of these noctur- 

 nal 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 in- 

 stance, sees with such exquisite acuteness in the dark, that 

 though the bam 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 Horned Owl is oftefi seen to 



capable of being tamed like the little homed or scops eared owl. It some, 

 times preys by day, and, from having been seen to pursue swallows, must 

 be strong and rapid on the wing. Its prey consists of mice, small birds, aud 

 insects— S"*e Selby'a Ornithology. 



