216 BRITISH BIRDS. [vol. xiv. 



of opening up oysters, and his observations were also made in the 

 State of Carolina. Prof. Newton, however, regarded Catesby's 

 statement as untrustworthy ; and later writers, with some exceptions, 

 have also doubted or denied the possibility of the Oystercatcher 

 feeding upon oysters. That the British species does not, at the present 

 time, open oysters, will, I suppose, be generally admitted. The 

 activities of H. paJliahis, in this connection, are, therefore, a matter 

 of some interest. In response to a request for further information, 

 Mr. Fleisher very kindly sent mc details of his observations and gave 

 his permission to have them published on this side. The following 

 is a transcript of the relevant part of his letter : 



" On Smith's Island at the mouth of the Cape Fear River in 

 south-eastern North Carolina there are extensive mud-flats exposed 

 at low tide. These are dotted with small and large clumps of 

 oysters (Ostrea virginica), consisting of old and young and dead 

 oysters in a solid mass. As I remember most of the oysters jioint 

 upward. In almost every clump that I noticed particularly, there 

 were some large old oysters and some young ones, the latter generally 

 on the periphery of the clumps. 



" The Oystercatchers were common where the oysters were, 

 and in almost every clump the small molluscs were open and empty. 

 The first one I looked at had a trace of flesh clinging to the shell. 

 Another in the same clump was clear of flesh, .\bout most of the 

 clumps, where the nature of the ground permitted, there was a 

 lace-work of tracks, which, I thought, included those of the Oyster- 

 catcher. I paid little further attention to the oysters and did not 

 actually see any birds operating on them. The birds were rather 

 shy. I might add that, while I took no measurements, I am sure 

 that none of the open shells, that I saw, was as much as three inches 

 long. ... I felt convinced that the birds did open and eat the 

 small oysters. In my paper I said ' . . . . the small clumps of 

 oysters on the mud-flats showed evidence of their work. In most 

 cases, the smaller molluscs on the outside of the clumps were the 

 ones that were opened and the larger ones left alone.' I realize now 

 that the evidence was circumstantial and may not be considered 

 conclusive. I do not remember whether any of the valves were 

 fractured. ... I am still of the opinion that H. paUiatits fed 

 upon the oysters at Smith's Island." 



Although, as Mr. Fleisher states, his evidence is only circumstantial, 

 I do not think there can be any doubt that H. paUiatns can and does 

 feed upon the smaller individuals of the American oyster, and that 

 Catesby was perfectly correct in his surmise. While //. pal/iatns and 

 ostralegiis appear to be much alike in size and appearance and in 

 strength of bill, there are considerable differences between Ostrea 

 virginica and O. edulis. Both are thick-shelled. But the former 

 grows more in length than in breadth as compared with the latter, 

 being four or live times as long as broad, while O. edulis is not much 

 longer than broad. This difference should give the adductor muscle 

 which closes the valves more purchase in O. virginica than in O. edulis, 

 the more so as the muscle is inserted distally to the centre of the valve. 

 Hence it would appear that H. palliatus has a bigger job in opening the 

 shells of O. virginica than it would have if O. edulis were its food-supply. 

 In view of Mr. Fleisher's observations, there is now no a priori reason 

 why H. osiralegus should not be able to open oysters ; and, in my 

 belief, it would readily do so if intertidal oysters were available on 

 the shores of this country, J. M. Dewar. 



Edinburgh, Dec. 1920. 



