Stomach-contents of Birds. 637 



even where butterflies had preponderated, there was often 

 quite a difficulty in detecting their presence in the ensuing 

 pellets, yet no difficulty whatsoever occurred over the hard- 

 chitined beetles and grasshoppers eaten along with them. 

 Tliere was an indication in one case that such tough, pliable 

 wings as those of the Danaida may form a partial exception 

 to the rule. 



These considerations should, of course, be quite as 

 applicable to other comparatively fragile-bodied insects, 

 arachnids, &c., as to butterflies ; and it seems to me some- 

 what unlikely that many insects of this kind will continue 

 to be readily recognisable for long after having been 

 swallowed; in other words, that the majority of those we do 

 readily recognise are probably recent captures. Even the 

 occasional abilitj'^ to recognise large numbers of Diptera — as 

 such — in a single stomach does not necessarily tell against 

 this view, when we remember the enormous numbers in which 

 these insects are often present and the rapidity witb which, 

 therefore, the stomach may have been filled with them 

 after the ejection of a pellet. 



How comes it then, if butterflies are not, as a class, 

 disliked, that they appear to have been less frequently found 

 in birds' stomachs than equally (or more) weak-chitined 

 insects of certain other Orders or than spiders ? 



Possible Reason 4. My observations and experiments 

 support the view that certain species of birds have become 

 specialized to prey on certain abundant orders, particularly at 

 Chirinda on Diptera, and probably, in the case of Sunbirds, 

 on spiders. 



In such cases it seems not unlikely that, so long as tli3 

 object of their special affections is present continuously and 

 in great abundance (and only so long), the particular birds in 

 question will seldom quite find " room inside '' for even tlie 

 pleasanter species, not only of butterflies, but, equally, of 

 the other Orders outside their favourite domain ; and that, 

 if shot at such times, members of these Orders will rarely be 

 found in their stomachs. 



Nevertheless, and this should be particularly noted, I have 



SEIl. IX. VOL. A I. .2 Y 



