Production of Mimetic BesemUanccs among Butterflies. 851 



33. Falco tinnunculus, L. (Kestrel), {a) This bird was 

 seen (near Swanage, Dorset) to capture numerous 

 butterflies {Argynnis aglaia and Mclanargia galatea) 

 by pouncing on them when settled on the ground. 

 The observer " found by counting that the bird caught 

 about thirty-six specimens in an hour, and it was hard 

 at it for at least five hours " : W. Parkinson Curtis, 

 "Entomol.,'' 1903, p. C8.— (&) "I would say that my 

 note on the Kestrel in the ' Entomologist ' in 1903 

 has been confirmed by repeated observations at the 

 same place, and presumably on the same pair of 

 birds every year since. In July 1904 I was a month 

 at Swanage and was at least a dozen times on the 

 Down in daylight, when the Kestrel was at its old 

 game of slaughtering Argynnis aglaia and M. galatea. 

 Last season (July 1905) aglaia was scarce and the 

 attacks were confined almost wholly to semele and 

 galatea; at least, the wings I saw mostly belonged to 

 those species": W. Parkinson Curtis (letter to Prof. 

 Poulton, 22, iv, '05). — (c) I have recently received 

 several further communications from Mr. Parkinson 

 Curtis with regard to his extremely interesting and 

 valuable observations on the feeding habits of the 

 Kestrel. On Aug. 8, 1907, he wrote : " On August 3 

 I had to go near the Ballard Down, so walked to the 

 place where I had generally seen the Kestrel ; it was 

 doing precisely the same thing as I have previously 

 recorded and at about the same average rate." On 

 Sept. 2 he Avrote : " On Sept. 1st I was collecting on 

 Studland Hill and Nine Barrow Down, that is about 

 2i miles from the Kestrels I have sent you a note 

 about. I saw three Kestrels catching butterflies; 

 they were at it, off and on, from 11.30 a.m. to 3.45 

 p.m., but I could not get near enough to see what 

 they were catching. That they were catching butter- 

 flies, all three, I am certain from the manner of 

 hawking, and their movements on the ground ; but 

 there was no cover for me to approach them, so I 

 cannot give you any precise details, except one female 

 semele which I put up and which flew in the direction 

 of one Kestrel and was promptly captured." In reply 

 to inquiries, Mr. Curtis informed me that Pierines 

 of all kinds were very scarce on the Downs frequented 

 by the Kestrel, and he had not actually seen any 



