572 THE BIRDS OF HELIGOLAND 



Diver Colymbus. This genus only contains four species, three 

 of which are residents of the north of Europe; the fourth, C. 

 Adamsi, is an American species, but is said to have occurred once 

 or twice on the coast of England. The first three species occur 

 more or less numerously on the sea in the neighbourhood of 

 Heligoland. 



381. Great Northern Diver [GROSSER SEETAUCHER]. 

 COLYMBUS GLACIALIS, Linn. 



Heligolandish : Groot Skwarwer. Skwarwer name for Diver. 



Eudytes glacialis. Naumann, xii. 397. 



Great Northern Diver. Dresser, viii. 609. 



Plongeon imbrin. Temminck, Manuel, ii. 910, iv. 571. 



In its beautiful breeding plumage this handsome bird is but of 

 rare occurrence off the island ; it may be seen at odd times during 

 May near the long reef to the north of the island, but it is very 

 rarely shot ; in fact, I can only remember three instances. In late 

 autumn and during the winter months, when wearing the obscure 

 grey plumage, it may be seen oftener near the island ; but being 

 a very wary bird, which generally knows how to escape from 

 danger at the right moment, cases of its being shot are none too 

 frequent. 



All diving birds when hotly pursued are endowed with the 

 capacity of immersing their body to such a depth that their back 

 is under water. Of this art the present species is a perfect 

 master, and, moreover, has at its command other contrivances by 

 which it is frequently able to trick its pursuer. As soon as the 

 bird's suspicions are aroused it immerses its body almost com- 

 pletely, and in this manner swims off with astounding rapidity. 

 If, however, it finds that it is being seriously pursued, it allows 

 only its neck to project above the surface, and will next take to 

 diving completely under. Instead, however, of making straight for 

 the sea-bottom in a more or less vertical direction, as it does when 

 diving after food, it sinks without further movement, leaving 

 hardly a trace of its presence on the water, and swims off hori- 

 zontally beneath the surface at such a rate that two expert oars- 

 men in a light boat, and rowing their hardest, will scarcely be 

 able to overtake it; the creature, well aware of this, only for a 

 moment projects its head above water in order to breathe, but at 

 once disappears again. By this time, however, it has already 

 become so exhausted that it is obliged to gasp for air with widely 

 extended beak. Seeing the uselessness of attempting to escape in 



