338 Mr. G. A. K. Marshall on Birds as a Factor in the 



were thus picked out. I noticed, however, that other 

 genera of their family (Pieridae) were much persecuted " 

 (Trans. Linn. Soc, xxiii, 1862, p. 511). And in the same 

 region Paul Hahnel noted that Pierines were more 

 attacked by birds than any other butterflies ("Iris," 1890, 

 p, 193). These facts render it difficult to accept the view, 

 advocated by Dr. Dixey and Professor Poulton, that the 

 Pierinae probably constitute a generally unpalatable 

 group. 



As might have been expected, the number of instances 

 in which birds have been observed to eat butterflies of 

 the dominant distasteful groups, such as Danainae or 

 Acraeinae, is comparatively small. Were these insects 

 as liable to be consumed as the Nymphalinae and Pierinae, 

 it seems likely, owing to their conspicuous appearance and 

 avoidance of concealment, that far more such cases would 

 have been forced upon the attention of casual observers. 



Again, it may be noted that many observers have 

 testified to the fact that it is by no means an easy task 

 for a bird to capture a butterfly in full flight, this being 

 true even of such adepts as the Bee-Eaters. My own 

 experience is entirely in accord with this opinion ; and we 

 may perhaps find here an explanation why a bird may 

 often be seen sitting apparently impassive and uninterested 

 in the butterflies which are flying in the vicinity ; the lack 

 of interest being due to the knowledge that open pursuit 

 is of little avail. It seems likely that attacks will in 

 general be made only under specially favourable con- 

 ditions, such as, when the butterfly passes very close to 

 the bird's perch, or when the attention of the insect is 

 distracted during feeding, courting, ovipositing, etc. We 

 are, therefore, probably justified in supposing that flight 

 does really afford an important protection to butterflies 

 against the attacks of birds. On the other hand, it has 

 been suggested that flight is probably of minor importance 

 in this connection, and that birds do not commonly pursue 

 butterflies simply because the vast majority of these 

 insects possess distasteful qualities to a greater or less 

 extent. This view I am quite unable to accept, for 

 various reasons which need not be discussed here ; nor 

 can it be said to find support in the following records, 

 which indeed furnish strong evidence against it. For 

 several observers, including Prof. Weismann, have testified 

 that butterflies bred in confinement and then released 



