20 THE BIEDS OF HELIGOLAND 



reliable weapons and good powder, may in the course of a 

 morning manage to bag as many as twenty-five or even thirty 

 birds. For this, however, it is necessary that one's boatman should 

 have some acquaintance with sport, and know the way to approach 

 the game. 



However, for the development of this scene of northern bird- 

 life in its utmost grandeur, a very severe frost and an easterly 

 wind, lasting for some weeks, are necessary conditions. Huge 

 masses of ice will then form during the ebb on the shallows along 

 the coast of Holstein, from the mouth of the Elbe here miles in 

 breadth westwards as far as the Weser. Covered by falling snow, 

 and flooded by the waves which wash over them, these masses very 

 soon attain a thickness of from three to six feet ; the next flood- 

 tides set the icefield afloat, and the east wind drives it out to 

 sea. This process is repeated with each succeeding ebb and flood, 

 so that the whole bay, from the coast of Jutland down to the Jahde 

 Basin becomes covered by a sheet of closely compressed and super- 

 imposed masses of ice and snow. With every ebb current this 

 icefield is driven nearer and nearer towards Heligoland, and finally 

 touches the island. Indeed, the process has occasionally assumed 

 such vast dimensions that the whole sea, even far out to the west, 

 has become covered with ice, so that, as happened in the years. 

 1845 and 1855, not the smallest surface of open water could be seen 

 even from the eminence of the lighthouse. 



The northern species of diving Ducks at the beginning of the 

 winter congregate along the strip of coast mentioned above, 1 where 

 they find shelter from the east wind and quiet feeding -places. 

 These are now driven by the ice into deeper water. At first, indeed, 

 the belt of ice is only a mile wide, and after being raised by the 

 flood-tide is pushed out to sea by the east wind, so that an open 

 surface of water is again formed between it and the shore, to which 

 the ducks will then also fly back. In the course of a few days, 

 however, the mass of ice increases to such an extent that the birds 

 are shut out from this means of escape and, being henceforth 

 compelled to travel out to sea in advance of the icefields, are very 

 soon brought up close to the shores of Heligoland. 



In the meantime the Baltic too has become covered with ice,, 

 and the numberless swarms of Ducks and Mergansers which had 

 intended to pass the winter there now fly in a westerly direction across 

 Holstein and join the already enormous swarms from the North. 



The sea in the neighbourhood of Heligoland is comparatively 

 shallow, a fact which considerably facilitates, for the birds frequent- 

 ing it, the task of diving for their food ; while of the food itself* 



1 i.e. the coast of Holstein, etc. (Tn.). 



