HEARING — FIELDWORK AND EXPERIMENTS 87 



ventilated from the top, but have a glass front and a door 

 at the side for the introduction of food. 



The next thing to do is to catch some large moths (or 

 cockchafers in the right season) . Enter the room where your 

 cage is situated without switching on the light, guiding your 

 own way to the cage with a very dim torch. Having got to 

 the cage, have your tin or jar containing your flying insects 

 ready, and hold this with the lid only just in place. Put out 

 your torch as soon as you have your other hand on the 

 cage-door fastening. Wait for some moments, and while 

 you are waiting, dispose of the torch where you can regain 

 it quickly. Take up the jar with your now free hand and 

 with the other quietly open the cage door sufficiently for you 

 to insert the jar (with the lid loose). Slide the lid to one side 

 and shake the jar inside the cage. Your insects will then be 

 freed. Shut the door and listen. You may be able to hear 

 your moths or beetles fluttering around, and you will without 

 doubt soon hear the plopping noise made by the bush-baby 

 as it leaps to and fro. Wait for some ten minutes, and then 

 either switch on the main room light, or take up your own 

 torch again. 



Inspection will usually show you that most, if not all your 

 insects, have now vanished. If you feel that further evidence 

 of their capture is necessary, you will probably have this 

 provided for you by the bush-baby itself, which may not 

 have finished its meal and will still be crunching away with 

 occasional licking of the lips. Not too many insects should 

 be given at one time — four or five will do. If this precaution 

 is not taken, you may find that some — moths in particular — 

 have settled soon after release, and these, of course, will be 

 caught by visual means as soon as the light comes on again. 



Another experiment on exactly the same lines as that 

 which I recounted in connection with my tame cuckoo, may 

 also be carried out. A bush-baby will hear mealworms 

 crawling about in a tin or paper bag and will at once pay 

 attention to the receptacle. This test can, of course, be car- 

 ried out in a lighted room so long as it is not too brilliant, 

 and so long as you take care not to let the bush-baby see 

 what you are preparing. Your subject may have nocturnal 

 sight, but it can see quite well in fighter conditions once it 



