ENEMIES AND MIGRATIONS. 487 



During the sealing-season in the Spitzbergen sea I have inva- 

 riably taken out of their stomachs various species of Gam- 

 marus {G. sabini, Leach, G. loricatm, Sab., G. pinguis, Kr., G. 

 dentatus, Kn., G. mutatus, Lilljeb., etc.), collectively known to 

 the whalers under the name of ' Mountebank Shrimps,' deriv- 

 ing the name from their peculiar agility in the water. This 

 'seals' food' is found more plentiful in some latitudes than in 

 others, but in all parts of the Greenland sea, from Iceland to 

 Spitzbergen ; I have seen the sea at some places literally swarm- 

 ing with them. Again, in the summer in Davis's Strait I have 

 found in their stomach remains of whatever species of small 

 Fish happened to be just then abundant on the coast, such as 

 the Mallotus arcticus, Salmo (various species), etc. I have even 

 known them to draw down small birds swimming on the sur- 

 face ; but their chief food is Crustacea and Fish. They also feed 

 on Medusae and Cuttlefish (Squids)." * That Seals vary their fare 

 with an occasional gull or duck is attested by numerous observ- 

 ers ; but birds form, of course, but an insignificant portion of 

 their diet. MalmgTcn also refers especially to the occurrence 

 in the stomachs of Erignatlius harhatus and other Seals of va- 

 rious species of crustaceans and moUusks, and sometimes of 

 fishes, t 



ENEMIES. 



Man is undoubtedly the Seal's chief enemy, but many fall a 

 prey to the Polar Bear, and doubtless, also, particularly in the 

 case of the young to sharks, and to that carnivorous Cetacean, 

 the Orca. They are also greatly subject to the attacks of intes- 

 tinal parasites. Many are also destroyed by the elements, 

 thousands being sometimes ground to pieces by the ice. They 

 are said to avoid rough water, but when amidst the ice-floes 

 are frequently killed by the jamming together of the ice in a 

 heavy sea. " At times during the spring, if there is a heavy 

 sea, the Seals are sure to mount the ice, and whilst on it, pro- 

 vided it runs together, they are certain to be jammed", at which 

 times many old Seals, as well as young, are destroyed.^ 



MIGRATIONS OF SEALS. 



The periodical movements of Seals have long been noticed, 

 and it has been found that a proper semi-annual migration is 



* Proc. Zool. Soc. London, 1868, p. 411 ; Man. Nat. Hist. Greenland, etc., 

 Mammals, 1875, pp. 40, 41. 



t Arcli. fur Naturg., 1^64, pp. 75-84. 



t Carroll, Seal and Herring Fisheries of Newfoundland, pp. 19, 20. 



