THE COLORAUON PROBLEM. 125 



The Coloration Problem. 



By W. PARKINSON CURTIS, F.E.S. 

 (Contimied from page lO'J.) 



Although it is not easy to say what is the object of attack, the 

 action of attacking an insect is unmistakable, because of the sudden 

 alteration of tactics on the part of the bird, the sudden pull up and 

 then the quick twists and turns. It is a matter of surprise to us to 

 find what an immense number of birds like insect diet. Besides the 

 regular insectivores, ciz., the Sijb-iidae (Warblers), Cypselidae (Swifts), 

 Capriiiudijidae (Night-jars) and Swallows and Martins {Hiriindinidae), 

 we have now noticed the major portion of the rasseriforuies, the Gulls 

 Larus canus and L. ridibiindus, the Stru/idae (Owls) and the common 

 Heron {Ardea cincrea). This last, unlikely bird, we noticed catch an 

 insect on the wing in July, 1912, in the Cam Valley. Reputedly 

 graminivorous birds dearly love insect food, and we notice that 

 Sturna vuhjaris (the Starling) and Frim/illa coelebs (the Chaffinch) 

 make a practice of frequenting tree tops in the late afternoon in order 

 to catch those insects which bask in the last rays of the dropping sun. 

 It may be noted in this connection that Pierids, Lycaenids, Satyrids 

 and Nymphalids in the late afternoon seek the upper parts of 

 trees to sun themselves. What is the logical conclusions to draw 

 from these observations? To my mind one only, viz., that insects, 

 including Lepidoptera, form a staple article of diet and are procured in 

 the manner one would expect from the habits of the bird. It is of 

 little use quoting the ornithologists on this subject, Mr. Marshall has 

 already pointed that out. Lieut. -Col. Manders has (1911 Trans. 

 Znol. Sac. Lond., page 696 et seij.), quoted their opinions on this point, 

 and they are, like their works, so vague as to be almost useless. 



I venture to suggest to Lieut. -Col. Manders, that his remarks 

 {loc. cit., page 711), with regard to Mr. Marshall's quotations, might pass 

 muster as a piece of smart pleading in a defence, where counsel had a 

 bad case to support, but that it leads nowhere in a matter of this 

 nature. None of the disputants have a case to make good, it is only 

 a question what is really the truth in the matter. Mr. Marshall was 

 quoting from ornithological works, and not giving his own observa- 

 tions, nor observations directed to this particular end, and an 

 admission on the part of an ornithologist was valuable, since it meant 

 that the attacks were sufficient to force themselves upon the notice of 

 an ornithologist. To argue, therefore, that he himself is entitled to 

 assume that the mere fact, that an ornithologist omits mention of 

 feeding upon lepidopterous imagines and only refers to Grasshoppers 

 and various other kind of coleopterous insects ! (the Italics this time are 

 mine), means that no lepidopterous imagines are attacked, is an 

 entirely unwarranted assumption. The fact is that the ornithologists 

 usually note that a bird will or will not eat an insect (usually 

 according to my experience when they say not they are wrong). But 

 if any insects be eaten they do not remark whether the food be a 

 Chalcid fly or Attaciis atlas, because, more often than not, they cannot 

 tell one from the other. The ornithologist who laboriously mounts 

 the contents of his birds' stomachs and then as laboriously identifies 

 the mounts is still a rarity. 



May 15th, 1913. 



