ARGENTINE COURLAN 173 



of the beak ; at the end it is of a horny toughness, 

 and frayed or split into filaments. This beak is a most 

 effective instrument in opening shells ; for where 

 molluscs abound the Courlan subsists exclusively 

 on them, so that the margins of the streams which 

 this bird frequents are strewn with innumerable 

 shells lying open and emptied of their contents. 



Every shell has an angular piece, half an inch long, 

 broken from the edge of one valve. Mussels and 

 clams close their shells so tightly that it would perhaps 

 be impossible for a bird to insert his beak, however 

 knife-like in shape and hardness, between the valves 

 in order to force them open j therefore I believe 

 the Courlan first feels the shell with his foot whilst 

 wading, then with quick dexterity strikes his beak 

 into it before it closes, and so conveys it to the shore. 

 Otherwise it would be most difficult for the bird to 

 lift the closed shell from the water and to carry it to 

 land J but supposing it could do this, and afterwards 

 succeed in drilling a hole through it with its beak, 

 the hole thus made would have jagged edges and be 

 irregular in shape. But the hole is, as I have said, 

 angular and with a clean edge, showing that the bird 

 had just thrust his beak half an inch or an inch 

 between the valves, then forced them open, breaking 

 the piece out during the process, and probably 

 keeping the shell steady by pressing on it with its 

 feet. 



By day the Courlan is a dull bird, concealing 

 itself in dense reed-beds in streams and marshes. 

 When driven up he rises laboriously, the legs dangling 



