244 BRITISH BIRDS. [vol. xv. 



OYSTERCATCHERS OPENING OYSTERS. 



To the Editors of British Birds. 



Sirs,— You may be interested to know that Oystercatchers {HcBtna- 

 topits ostralegiis) at present in the Scottish Zoological Park, have been, 

 almost certainly, opening oysters put out for them. Unfortunately 

 no one, so far, has witnessed the act, as the birds are intolerably shy 

 in the presence of humans. But no other bird in the waders' aviary 

 is likely to have tackled such a stiff problem as an oyster, so that it is, 

 as I have said, almost certain that the Oystercatchers have done so. 

 I tried the experiment last winter without any success. This winter 

 I had two more birds to work with, and these were fresh from the sea- 

 beach. After a fortnight's work on mussels (Mytilus) the birds 

 apparently tackled the oysters at once. Out of the first six bivalves 

 put out five were opened and cleaned in not more than five days. Of 

 two in my possession one has evidently been dealt with like a limpet, 

 while the other shows signs of long-continued chipping or gouging 

 along the edge of one valve. These two shells are 4.5 and 5 cm. in 

 length respectively. I am continuing the experiment, and hope that 

 some one may be fortunate enough to witness the act of opening an 

 oyster before all the shells I have are used up. 

 Edinburgh, January 19th, 1922. J. M. DewaR. 



ALBINISTIC GULLS AND IVORY-GULLS. 



To the Editors of British Birds. 



Sirs, — Regarding the Rev. F. C. R. Jourdain's note {antea, p. 214), 

 I quite agree with him that my record of a probable Ivory-Gull at 

 Cardiff, April 3rd, 1921, cannot be accepted as indisputable, especially 

 in view of the fact that this bird, or a similar one, was seen again as 

 late as June 13th. On the other hand, Mr. Salmon and myself are 

 absolutely agreed that it was not an albinistic specimen of any of the 

 six species of Gulls that visit us during the winter, viz. : Black-headed, 

 Common, Herring, Lesser Black-backed, Great Black-backed and 

 Kittiwake. It was seen in the company of, and compared with, the 

 first three species mentioned, when its size immediately separated it 

 from the Black-headed and the Herring-Gulls, and although it agreed 

 with the Common Gull in this respect, looking if anything slightly 

 larger, its carriage, shape and flight were totally dissimilar. Confusion 

 with the Lesser and Great Black-backed Gulls and Kittiwake is 

 also impossible on account of size and shape. It is improbable that 

 an albino would differ from the normal in anything but colouring, but 

 it would be expected that the beak, eyes and legs would lack colour 

 as was the case in the two specimens mentioned as occurring off the 

 Essex Coast and in Bridlington Bay, Yorks. 



The suggestion that " April is a very unlikely time for an Ivory-Gull 

 to visit us "is not altogether supported by previous records. A specimen 

 was obtained in Yorkshire, April 5th, (Brit. Birds Vol. II., p. 329) another 

 in Orkney April ist {Brit. Birds Vol. IX., p. 28), and there are also 

 two records from Ireland March 25th and March 27th. If nothing 

 more had been seen of the bird after April 3rd, there Would have been 

 no doubt in my mind as to the species. Although it is extremely 

 improbable that an Ivory-Gull would remain in this country until 

 so late a date as June 13th, it is the only species that in any way 

 resembles the specimen observed. 

 Cardiff, Feb. loth, 1922. Geoffrey C. S. Ingram. 



