NOTE ON THE OYSTERCATCHER. Ill 



it is a semilune, the circumference of the circle of which it forms 

 part intersecting that of the first opening. The edge is either 

 straight or bevelled inwards. This second and larger portion is 

 found rarely in one piece. The greater part of the contents is 

 now accessible. The mollusc is removed piecemeal, each part 

 being seized and shaken from the shell in three or four mouth- 

 fuls. Just as the Oystercatcher may fail at the first stage, so 

 it may be unequal to the second. In this event it removes 

 through the first opening as much of the soft parts as are within 

 reach. 



On sand the shell sinks under the force applied to it with an 

 inclination towards that side on which the force is greater, and 

 one can learn indirectly by which method the force was applied. 

 During the second stage a column of sand rises through the 

 aperture to the first opening, and, adhering to the flesh, obscures 

 much of it, or renders it distasteful. On the other hand, one 

 may suppose that the yielding sand diminishes the shock which 

 the bill has to sustain. 



So far I have sketched what appears to be the general mode 

 of attack, and what is certainly its common result when the 

 attack is successful. The ideal result seems to be the extrusion 

 of a piece of shell, equal in area to that of the two discs, at the 

 first stage, so that the Oystercatcher can clear out the contents 

 of the shell with the minimum of trouble. The extruded por- 

 tion may be in one piece, or broken up into two or more 

 fragments. The gap formed in the shell is irregularly pear- 

 shaped or elliptical in outline, and does not show the symmetrical 

 dentation characteristic of the type. Sometimes the Oyster- 

 catcher, falling short of its ideal as it were, is content to make 

 the first small opening, and, without reversing the position of the 

 shell, to remove a portion of the soft parts by poking its bill in 

 from below. 



As to the frequency with which the Oystercatcher attacks 

 the Purple-Shell, my own experience indicates that the act 

 occurs locally and very irregularly. Days pass, and no opened 

 shell is seen on the feeding-grounds ; on single days I have 

 gathered eight or nine. A habit may be developed on parts of 

 the extended coast-line of this and other countries, but there are 

 reasons why it should not be. I happened to witness an Oyster- 

 catcher attack seven shells in succession. It failed to gain 



