TERNS. 81 



breeds on the islands of that yet untrodden region, inhabited by several other species 

 of birds, the breeding grounds of which have not been reached by the explorer and 

 collector. In winter it probably follows the edge of the ice, thus avoiding the shores 

 and the vicinity of man. 



The gulls having already occupied more space than was originally allotted them, 

 we will have only to mention the kittiwakes (Hissa tridactyla and brevirostris) popu- 

 lating the Arctic bird-rookeries, the dazzling white ivory-gull ( Gavia alba) from the 

 icy circumpolar regions, and the fork-tailed gulls, constituting the genus JCema, one 

 of which, X. sabimi, inhabits the high north, while the other, X. furcata, a bird ex- 

 tremely rare in collections, is a resident of a probably very restricted area in the 

 tropics, possibly of the Galapagos Islands alone. 



Of those just mentioned., the kittiwake is perhaps most interesting, because of 

 the immense number of birds composing their breeding colonies, an account of which 

 will be of great interest, and we therefore take pleasure in introducing the following 

 sketch, by Henry Seebohm, of one of those rookeries. 



" The largest colony of birds which I have ever seen is that at Svaerholt, not far 

 from the North Cape, in Norway, on the cliffs which form the promontory between 

 the Porsanger and the Lakse Fjords. It is a stupendous range of cliffs, nearly a thou- 

 sand feet high, and so crowded with nests that it might easily be supposed that all the 

 kittiwakes in the world had assembled there to breed. The number of birds has, 

 however, been grossly exaggerated. If we estimate the surface of the cliff covered 

 by the nests at about 640,000 square feet, and allow for each nest a foot in width and 

 two feet and a half in height, we obtain a total of (say) a quarter of a million breed- 

 ing birds. Supposing the non-breeding birds to be ten to one, surely a very high esti- 

 mate, we only reach live and a half million birds. When a recent writer says that 

 ' the number of individuals must amount to milliards,' or thousands of millions, he is 

 simply talking unmitigated nonsense, and obviously has no conception of what a mil- 

 liard is. One milliard kittiwakes laid in a row, and touching one another 1 , would reach 

 twenty times round the world. But in spite of all this tall talk, the number is in- 

 credible. It is the custom to fire off a cannon opposite the colony ; peal after peal 

 echoes and re-echoes from the cliffs, every ledge appears to pour forth an endless 

 stream of birds, and long before the last echo has died away, it is overpowered by the 

 cries of the birds, whilst the air in every direction exactly resembles a snowstorm, but 

 a snowstorm in a whirlwind. The birds fly in cohorts ; those nearest the ship are all 

 flying in one direction, beyond them other cohorts are flying in a different direction, 

 and so on, until the extreme distance is a confused mass of snowflakes. It looks as if 

 the fjord was a large chaldron of air, in which the birds were floating, and as if the 

 floating mass was being stirred by an invisible rod. The seething mass of birds made 

 an indelible impression on my memory; it photographed itself on my mind's eye, 

 as such scenes often do." 



The chief characteristic of the terns, as distinguished from the gulls, have already 

 been given on a previous page. In their habits they resemble the gulls, especially the 

 smaller species, but in the same way as their appearance and structure is, so to 

 speak, a kind of intensification of the gull type ; so are also their habits and peculi- 

 arities, like those of the gulls, in a maximized and intensified degi-ee. Let us, for 

 instance, mention only their curiosity. Thus writes J. F. Naumann, the famous 

 German ornithologist, of Sterna paradiscea, the arctic tern : "When something new 

 happens, such a bird soon arrives, inspects it closely, and, fluttering over it, gives out a 



VOL. IV. 6 



