404 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



groove along each side of culmen, nostrils completely closed in 

 adults. Lores, chin and upper part of throat more or less bare. 

 Wings very long and pointed, 1st primary longest, tail long, wedge- 

 shaped, 12 to 18 rectrices. Top of toes and tarsus reticulated, but in 

 Sula bassana one row on top of toes and continuation in three rows 

 up tarsus with transverse scutes. All four toes connected by webs. 

 Body -plumage fairly hard and close. Tarsus shorter than foot. 

 Claw of middle toe wide and pectinated on inner edge. Sexes 

 alike. Rock-inhabiting sea-birds, plunging divers, food fish. 

 Tropical and temperate seas, S. bassana north to Iceland. One 

 genus of about a dozen species and subspecies, unnecessarily 

 divided into several genera or subgenera, according to number of 

 rectrices and covering of toes. 



Genus SULA Briss. 



Sula Brisson, On., i, p. 60 (1760 — Type according to vi, p. 464, Sula 

 Brisson =#. leucogaster, by tautonymy). 



Characters, etc., see under family Sulidaz. One British species. 



SULA BASSANA 



331. Sula bassana (L.)— THE GANNET. 



Pelecantts Bassantjs Linnseus, Syst. Nat., ed. x, i, p. 133 (1758 — 



Scotland, America). 



Sula bassana (Linnseus), Yarrell, iv, p. 155 ; Saunders, p. 365. 



Description. — Adult male and female. Summer. — Crown, sides of 

 head and neck yellowish-cream ; whole of rest of body-plumage, 

 tail-feathers, secondaries, and lesser, median and greater wing- 

 coverts pure white (shaft of tail-feathers pale straw-colour) ; prim- 

 aries black-brown, paler on inner webs and shafts whitish at base ; 

 primary-coverts and bastard-wing black-brown ; lesser primary- 

 coverts along edge of wing sometimes pure white and sometimes 

 with black feathers intermixed. This plumage is acquired by a 

 moult in spring, but whether this is complete or confined to the 

 head only I am unable to say as I have had no material collected 

 in March and April for examination. Winter. — A complete moult 

 takes place July-Dec. and even sometimes as late as Jan. and Feb.* 

 Plumage as summer, but whole crown, sides of head and neck not so 



* Over twenty collected in Sept. were all moulting primaries and this moult 

 appears to be rapid as in all cases two primaries separated by full-grown ones 

 were growing in each wing (often at slightly different stages of growth in 

 ■each wing). The fact that all these birds in Sept. were in moult makes it 

 surprising that the period (July to Feb.) is so long in which adults may be 

 found moulting their wings. The Dec, Jan., and Feb. birds were all adults 

 and had all nearly completed the moult and the feathers of their heads were 

 newly-grown winter ones and not the yellowish feathers of the summer 

 plumage. Mr. Gurney informs me (in litt., Sept. 2, 1921) that his two adult 

 captive birds shed a few of their wing-feathers in May and June but he states 

 that the birds were never in a very healthy condition. — H.F.W. 



