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VARIETIES OF THE COMMON GANNET. 



BY 



HENRY BALFOUR, m.a., f.z.s., f.r.g.s. 



The Gannet {Sula bassana) in the adult state appears to be 

 but little subject to variation, and one very rarely sees note- 

 worthy instances of a departure from the normal. Hence, 

 plumage or other variations, when they occur, are worth 

 placing upon record. The adult bird with dark buff head 

 and neck and with the back mottled all over with the same 

 colour, which was reported by Mr. J. Atkinson and Mr. Riley 

 Fortune as having been seen by them on the Bass Rock in 

 July 1910, excited a good deal of interest, but, at the same 

 time, provoked controversy, as doubts were expressed as 

 to this being a natural "sport." Not having seen this bird, 

 I can offer no comments upon it, and can merely say that, 

 while recognizing the high value of an opinion expressed by 

 these two distinguished ornithologists, one cannot but admit 

 the force of Mr. Gurney's argument against their view {The 

 Gannet, p. 488). If the variety can be proved to have been 

 valid, it would be a most interesting, if, physiologically, 

 disconcerting sport. 



Two interesting abnormal Gannets have recently come 

 under my personal notice, and about the validity of these 

 there can be no question. In July of the present year my 

 son and I spent three weeks on the Bass Rock, living in 

 the lighthouse. On the first day, July 5th, while standing 

 on the top of the north cliff watching the Gannets flying 

 past in hundreds, one of them caught my eye while it was 

 still a good way off. As it circled round and, meeting the 

 wind, sailed slowly past the cliff edge, very close to where 

 I was standing, I saw that it was a pure white example, 

 fully adult, the white extending to the tips of the primaries, 

 which normally are black, or, rather, very dark brown. 

 Not a single dark feather was to be seen, though the buff 

 coloration of the head and nape was normal, though very 

 pale. I pointed this bird out to my son and Mr. Muir (the 

 principal lighthouse-keeper), who were with me at the time. 

 We saw this bird again on subsequent occasions, but, unluckily, 

 my son was not able to secure a photograph of it. Un- 

 doubtedly a case of albinism, and, therefore, merely exhibiting 

 a variation from the normal which is by no means uncommon 

 in many species of birds. At the same time, it is the first 

 instance of the kind among Gannets of which I have seen 

 any record, and I have seen many thousands of these birds. 



