328 STRIGIN^. 



only in the twilight. The eye being extremely large, 

 and the iris extremely sensible, and contractile or ex- 

 pansile in a greater degree than that of any other birds, 

 they are enabled to adapt the size of the pupil to the 

 degree of light. But although by far the greater num- 

 ber prey in the twilight, by moonlight, or in the shade 

 of woods, some fly in open day. Their sense of hear- 

 ing must be more acute than that of other birds, if one 

 may judge by the size of the auditory apparatus. 



Their flight is extremely light and buoyant, gliding, 

 protracted when necessary, performed by rather slow, 

 regular flaps of the extended wings, and so noiseless 

 that even in a room one scarcely hears it. They fly 

 in an apparently hesitating unsteady manner, searching 

 the fields as they proceed, sometimes hovering, then 

 sailing or skimming along, and again rowing them- 

 selves gently forward. 



They perch on trees, rocks, or other elevated objects, 

 and rest chiefly by day, but probably also at night in 

 cloudy weather. They are incapacitated from walking 

 in an eff^ective manner by the structure of their feet, 

 but grasp their perch with great security. When 

 standing on a flat surface, they incline the body for- 

 wards, and keep only the first toe behind, the fourth 

 being stretched outwards or forwards ; but when on a 

 narrow surface, such as that of a branch, they bring the 

 fourth toe backwards, placing it and the first in opposi- 

 tion to the rest, and securing their hold by means of 

 the tips of their claws, which are much bent for the 

 purpose. 



They are solitary, or live in pairs, and none of our 

 species are in any degree gregarious. When they 



