33G Mr. G. A. K. Marshall on Birds as a Factor- in the 



years in Burma, where these birds are not uncommon, only 

 once observed a butterfly to be seized by one of them. It 

 might be argued that if so admirable and skilled an 

 observer, in the course of a long experience, saw this 

 happen only on a single occasion, the pursuit of butterflies 

 must be an unusual habit with these birds. But for- 

 tunately, we have some indirect evidence on this point 

 which aptly illustrates how extremely misleading such an 

 argument may be. These hawks nest in holes in trees, the 

 bottom of the hole being lined with a thick pad composed 

 chiefly of insect remains mixed with rotten wood. Now 

 three different observers have found nests iu which this pad 

 consisted largely, or even principally, of butterflies' wings, 

 thus rendering it extremely probable that the Falconets do 

 prey upon these insects to a very considerable extent. 



But if records of birds taking butterflies are scarce, it 

 must be borne in mind that the same thing applies to 

 almost all orders of insects. For example, although 

 Coleoptera are very largely eaten by birds, yet it must be 

 admitted that our knowledge of that fact is not really based 

 on direct observation of capture, but is derived from an 

 examination of the contents of birds' stomachs ; and it is 

 probable that the number of authentic records of capture 

 would be even less in the case of beetles than in butterflies. 

 If it be urged that the small size of most Coleoptera renders 

 their recognition difficult under such conditions, let us turn 

 to the dragonflies, which afl'ord a very fair parallel to butter- 

 flies, so far as size and habits are concerned. Here again 

 my examination of the literature of the subject shows that 

 the observed cases of capture, or even pursuit, are ex- 

 tremely few ; and personally, during fifteen years of field 

 experience in South Africa I cannot recollect to have ever 

 seen a bird pursue a dragonfly. But I am by no means 

 prepared to assume from these facts that birds never, or 

 very rarely, attack dragonflies ; rather do I believe that 

 this dearth of evidence is simply due, as it certainly is in 

 my case, to the fact that no attention has been ])aid to this 

 line of inquiry. This belief is borne out by the know- 

 ledge that where birds' stomachs have been critically 

 examined the occurrence of dragonflies has been noted in 

 quite a number of cases. An exhaustive examination of the 

 insect remains found in the stomachs of wild birds, must, 

 in most cases, aff^ord the only satisfactory testimony as 

 to what constitutes their normal food ; but no such in- 



