690 Mr. M. J. Nicoll on the Birds collected and 



— Sula pjscator (Linn.). 



Sula piscator Ridgway, Proc. U.S. Nat. Mus. xviii. p. 524 

 (Glorioso). 



Sula piscatrix, Grant, Cat. B. B. M. xxvi. p. 432. 



One adult male (brown phase), one immature female. 



Iris dark brown; bill lavender, base of both mandibles 

 red; round the eye bluish, sac jet-black; tarsi and toes 

 cherry-red. 



This Gannet offers one of the most complex problems that I 

 have ever met with in birds. In Little Cayman Island, W. I., 

 we find a Gannet which is doubtless Sula piscator, yet having 

 a stage in which the rump, tail, and vent are white, while 

 the rest of the plumage is brown. In that place, however, 

 examples are always to be found in transition from such 

 plumage to the white plumage of the really adult bird ; 

 although the brown birds with white tails, &c, breed in 

 that plumage and have black gular sacs, a sign of maturity 

 (cf. Ibis, 1904, pp. 588-589). 



On Glorioso we find a somewhat similar state of things, 

 though in this case nearly the whole of the Gannets on the 

 island are in the brown plumage, with white tails, vents, &c, 

 and, what is more remarkable still, they apparently, instead 

 of getting lighter brown and then white, as might be 

 expected, become darker greyish brown as they get older. 

 The first plumage is similar to, though slightly darker than, 

 that of the same aged Sula piscator from other parts of the 

 world; but when they assume the " white-tailed plumage," 

 the rest of the body, &c, is quite a shade darker. To the 

 best of my belief, I did not see a single speckled Gannet on 

 the island of Glorioso, though on the neighbouring islands, 

 Assumption and Aldabra, speckled birds, i. e. birds moulting 

 straight from the brown-tailed plumage into white plumage, 

 are the rule. On Glorioso at least ninety per cent, of the 

 Gannets are brown-plumaged birds with white tails, and this, 

 coupled with the fact that they are darker in colour, almost 

 decided me to describe them as of a distinct species. But 

 knowing, as I did from experience, that the Cayman Gannets 

 have a similar plumage, although they moult from that into 



