SIGHT — FIELDWORK AND EXPERIMENTS 63 



or Barn Owls are the most profitable to watch — has been 

 located, all that has to be done is to take up position at the 

 most favourable vantage point and be ready to devote some 

 hours to your vigil. A good pair of night glasses is a help, but 

 not absolutely necessary; but a position should be selected 

 so that as much light as possible is available to make your 

 task easier. Nearly any entrance hole, be it in a tree, barn 

 or other building, will have some angle from which it can be 

 viewed better on any night save a pitch dark one. 



The object of watching owls at their breeding time is to 

 be able to gain some idea of the numbers of "kills" brought 

 in and then to relate them to the conditions of light at the 

 time and also to the question of wind and rain. I have already 

 referred to the difficulty of dealing with one sense without 

 some other sense being also taken into consideration ; and it 

 is in connection with weather and light conditions that one 

 must remember that owls have to adapt their feeding 

 methods to quite a considerable extent. 



On moonlight nights or on reasonably light nights, without 

 appreciable wind, owls will hunt mainly by sight ; but if the 

 night is very dark indeed, or if there is much rain, or it is 

 very windy, owls will rely much on their ears to aid them in 

 hunting. On the whole a fair number of kills will be made 

 even when light conditions are bad so long as there is no 

 strong wind or heavy rain ; but on really unfavourable nights 

 the number of kills will fall off quite noticeably. 



The watching of owls is perhaps one of the most promising 

 activities from the point of view of the student of animal 

 senses, since by careful notes of what is observed over a 

 period of some weeks and by paying equal attention to the 

 weather, information about the seeing abilities of owls and 

 about their hearing abilities may be acquired at one and the 

 same time. 



While the period during which owls are feeding young is 

 certainly the most easy for watching, it is quite feasible to 

 watch owls at other times of the year, though this is never 

 so easy. First, one must have definite knowledge of the 

 presence of owls in some particular area or suitable habitat; 

 and then, having located them, much time and patience 

 must be devoted to watching for signs of hunting. With luck 



