810 MR. R. I. POCOCK ON THE 



collection. In the second place, those that were in the Zoological 

 Gardens at the time were, in most cases, kept in a very large 

 flight aviary with plenty of cover in the way of shrnbs, repre- 

 senting their natuial environment as nearly as possible. Never 

 having been tamed by confinement in small cages, they were too 

 shy to come to the bars to take insects from my hand and too 

 scai'ed to notice them if I entei'ed the aviary. Once or twice 

 I tried the expeiiment of libei'ating butterflies in this aviary ; 

 but the frequency with which they escaped through the wire 

 mesh and were wasted for the purpose in hand, induced me to 

 abandon further experiments of that kind. 



This reference to the shyness of birds in captivity brings me 

 to another of the limitations under which I was working. I 

 was forced to restrict my attention to particular birds, tame 

 enough either to take insects directly from me or sufficiently 

 accustomed to the presence of human beings in the aviary to 

 capture liberated insects in spite of my close proximity. If I 

 put the insects through the bars, myself standing outside, they 

 were either seized one after anothei- by the boldest bird in the 

 place, or were carried by a timid bird to the back of the com- 

 partment, where I could not watch what befell them. I was 

 compelled, therefore, to be inside the bars. Since, moreover, 

 it was practically impossible to watch more than one bird at a 

 time, I was precluded from the method of experimenting with 

 the shyer specimens by giving insects to the bolder ones to 

 distract and monopolize their attention. Thus it comes about that 

 the same species appear over and over again in the experiments 

 below recorded, while many insectivorous birds, that might have 

 been tried but for their shyness, are omitted. 



Two facts struck me very forcibly at an early stage of the 

 experiments. The first was the exceeding keenness of the birds 

 for the insects brought to them. This was no doubt due in a 

 measure to our inability in the Gardens to feed the birds on 

 living insects other than mealworms. The living prey was 

 evidently a great treat to them ; and over and over again I was 

 impressed with the persistence shown by birds in persevering 

 with insects that were obvipusly not to their liking, returning to 

 the morsels repeatedly as if food of such a nature was too good to 

 be wasted. From this I think it may be inferred that in a state 

 of nature hungry birds will eat nauseous insects which in times 

 of plenty they will reject after tasting, or will not take the 

 troiible to catch them if they have previously learnt their distaste- 

 fulness by experience. Furthermore, it is quite clear that the 

 plain record of an insect being eaten is no proof of its palatabilitj''. 

 Better evidence on this head is supplied by the behaviour of 

 the bird towards it. After a little experience in this matter, I 

 was able to satisfy myself at all events as to the ajaproximate 

 correctness of my inter j)retation of the bird's actions, and to 

 judge thereby of the comparative palatability of the insects they 

 tasted. 



