SIGHT FIELDVVORK AND EXPERIMENTS 6l 



eye structure of our owls will vary according to the habit of 

 the species in question. 



As far as field observations are concerned, these are not 

 so difficult to undertake as when observing smaller birds. 

 A visit to good Short-eared Owl country will seldom go un- 

 rewarded ; for the owls will usually be in evidence, and they 

 are easy to watch as they go up and down their feeding terri- 

 tory. Voles are their most usual prey, and the number of 

 kills they are seen to make in a given time will, to some 

 extent, give an indication of the numbers of voles present. 

 The only difficulty that will be encountered is in deciding 

 whether a particular owl under observation is making cap- 

 tures by means of its eyes or its ears. 



Should the type of country being covered by the owl be 

 rough ground with short grass, or a freshly mown meadow, 

 it may be reasonably deduced that kills are the result of 

 what has been seen. If, however, the country is a large area 

 of rough tussocky grass (which is particularly good for Short- 

 eared Owls) their sight will not play the main part in hunting 

 behaviour ; the hearing of these remarkable and beautiful 

 birds will be the sense used. It may be appropriate here to 

 mention that the ear-tufts of the Long and Short-eared Owls 

 have nothing to do with their hearing. They are probably 

 used in display. 



Little Owls may frequently be seen perched on fences, 

 posts and the branches of trees, where they are keeping a 

 constant look-out for their varied prey. Attention will be 

 drawn to them on account of their habit of bobbing their 

 heads if they see that they themselves are under observation. 



I have spent much profitable time watching Little Owls 

 in daylight, and have seen them swoop down on voles, lizards 

 and newly fledged birds, and twice I have seen one fly after 

 and catch an Emperor Moth as it flew over the heather — 

 probably a male moth on the trail of a waiting female. 



Such incidents as I have just described will give plenty of 

 evidence of the sharpness of vision in daylight. All the same 

 it must never be forgotten that not only does the prey of 

 owls vary according to the season of the year, it also varies 

 with the time of day. Owls in general, but the Little Owl in 

 particular, are fond of beetles. Some beetles are about in the 



