FEEDING-HABITS OF THE DUNLIN. 



7 



in the wash of the sea and in streams, for small insects and 

 spiders* crawling on the land, but the common form of surface- 

 feeding is the capture of small univalves. When the acorn- 

 shells that encrust the rocks in many places die they leave 

 behind them rings of lime, each narrowing towards the top and 

 adherent to the rock at the base. In these asylums small Peri- 

 winkles dwell in comparative safety, and wherever they are 

 numerous they become objects of interest to the Dunlin. At 

 certain times molluscs are seen in large numbers on expanses of 

 sand after the tide has ebbed, and in myriads on the ooze of 

 some land-locked bay or harbour. The Dunlin, attentive to the 

 signs, runs swiftly over the sand, turning at the end of its beat 

 to cross the area in a fresh direction. When a considerable 

 number are present the general effect of the crossing and re- 

 crossing is of a game of inviting and avoiding collisions which 

 may go on ceaselessly for an hour at a time, and it is only 

 at long intervals that a Dunlin is seen to bend down and seize 

 hold of a small univalve. At any time it may turn aside from 

 its course with the utmost rapidity to take a mollusc which has 

 caught its eye in passing. The same thing occurs on the mud 

 and on the rocks, only the speed is limited by the nature of the 

 ground. They run shorter distances at a time, and incline to 

 move in one general direction, though they run this way and 

 that as the signs dictate. Here again they pick up shells at long 

 intervals of time and space. 



From a study of the birds' habits alone it is difficult to under- 

 stand this boundless display of energy, and if the gizzards were 

 not packed with shells! the actions of the Dunlins might be 

 taken to prove that something else was the object of pursuit. On 

 the sand and rock the shells are present in hundreds, on the 

 mud they are crowded together so closely that scarcely an inch 

 of ground separates one from another, yet the Dunlins select a 

 shell here and a shell there for some reason or other. True the 

 shells on the sand vary in size, and many of them are too large 

 for the Dunlins' throats to pass, while in the case of the shells 

 on the rocks a limit is imposed by the relative size of the Peri- 

 winkles to that of the surrounding rings. But these restrictions 



* Alston, « Zoologist,' 1866, p. 513. 

 f Swinhoe, 4 Ibis,' 1863, p. 412. 



