Production of Mimetic Eesemhlances among Bittterjlies. 335 



may be easily overlooked, I may refer to the case of the 

 kestrel in England. I have searched in vain through 

 many books on British Ornithology for any record that 

 this bird eats butterflies; nor is it even mentioned in 

 Naumann's " Vogel Deutschlands " (1822), which contains 

 much more information of this kind than most modern 

 works. Yet in the "Entomologist" for 1903 (p. 68) 

 there is a most interesting account by Mr. Parkinson 

 Curtis of the behaviour of a kestrel which he observed 

 for some hours on the Ballard Down, near Swanage. 

 The bird was seen to stoop on several occasions at 

 something on the ground, but always rose again without 

 carrying off anything. Most entomologists would have 

 troubled themselves no further about the matter, but, 

 fortunately, Mr. Curtis was prompted to make a closer 

 investigation, and by carefully stalking the bird he found 

 that it was pouncing upon butterflies which it tore to 

 pieces on the ground. In the course of an hour he 

 counted about thirty-six specimens which were captured in 

 this manner, and the bird was observed to continue the 

 pursuit for at least five hours. Nor is this merely an 

 isolated case, for Mr. Curtis has confirmed his observation 

 in every succeeding summer; moreover we have the 

 evidence of Mr. Colthrup that he has seen the kestrel 

 feeding on Folyommatus corydon (see p. 352) in 1906 and 

 1907 on Beachy Head. It is therefore probable that 

 further enquiry will show this to be quite a usual habit 

 of the kestrel which has hitherto been overlooked ; and 

 it seems quite conceivable that dozens of entomologists 

 may have collected on Beachy Head and Ballard Down 

 and have remained in ignorance of the destruction of 

 butterfly life which may have been going on in their very 

 presence. Again I can find no record of butterflies being 

 eaten by the Garden Warbler {Sylvia hortensis), with the 

 exception of the one published by Professor Kennel (see 

 p. 344), who observed a pair which fed their young almost 

 exclusively on butterflies all day long. It would be 

 unreasonable to suppose that this must be an abnormal 

 case ; it seems far more likely that this Warbler does 

 often capture butterflies, but that naturalists have failed to 

 observe the fact, or else failed to record their observa- 

 tions. A final instance may be referred to, namely, the 

 Pigmy Falcons {Mio^ohierax) of the East. My lamented 

 friend, the late Col. C. T. Bingham, who lived for many 



