-176 THE ZOOLOGIST. 



A lofty arch runs right through the rock. Its direction in tne 

 Ordnance Sheet is due N. and S., and it is over this arch, at 

 both ends, that the Gannet breeds in greatest numbers. Over 

 the southern entrance they are most numerous, occupying every 

 shelf and ledge on the cliff, from the top of the arch to within 

 thirty feet of the top of the Bull. At least 150 feet of the cliff 

 is here literally white with Gannets. I estimate the number 

 breeding on this, the southern face, at 1200 to 1500. Some 

 two hundred feet over the northern entrance to the arch the 

 blasting operations are in progress, and far fewer Gannets breed. 

 Indications are not wanting, however, to show that here also 

 they must have had a large colony ; but the showers of stones 

 falling down the cliff from the top of the island have banished 

 all but a few courageous birds, which still cling to their nests, and 

 sit hatching as the rocks and debris fly past and even over them. 

 No Gannets breed on the east side, but on the western face there 

 are several nests. Altogether perhaps 2000 breed on the Bull. 



In ' The Zoologist ' for 1876, p. 5048, Mr. J. H. Gurney, jun., 

 put a query about the materials of Gannets' nests, quoting 

 from H. Boece (1526), Willughby (1678), and others. Mr. 

 Gurney found all the Gannets' nests he examined on the Bass 

 Eock to be composed of seaweed mixed with grass. At the Bull, 

 seaweed predominated, but a few nests had some grass mixed 

 with it. The island of Borrera (1072 feet), at St Kilda, has in 

 the breeding season a flock of Gannets frequently on its grassy 

 top, pulling materials for their nests. Martin, who visited 

 St. Kilda in 1697, in his ' Voyage' to that island, says (at page 8), 

 that two Gannets " confirmed the truth of what has been 

 frequently reported, of their stealing from one another grass 

 wherewith to make their nests, by affording us the following very 

 agreeable diversion, and it was thus : one of them finding his 

 neighbour's nest without the fowl, lays hold on the opportunity 

 and steals from it as much grass as he could conveniently carry 

 off, taking his flight towards the ocean ; from thence he pre- 

 sently returns as if he had made a foreign purchase, but it does 

 not pass for such, for the owner had discovered the fact before 

 the thief had got out of sight, and, too nimble for his cunning, 

 waits his return, all armed with fury, and engages him des- 

 perately; this bloody battle was fought above our heads, and 

 proved fatal to the thief, who fell dead so near our boat that our 



