°' 1919 J Robbins, Cape Cod Piping Plover. 3o3 



extreme measures, collapsing utterly a short distance away as if 

 completely exhausted. 



They always make their nests on the dry upper beaches but, 

 like various other shore birds, feed commonly along the water's 

 edge where the moist sand teems with myriads of minute living 

 creatures. Here, as they run back and forth, the comparatively 

 dark background makes them conspicuous even from some little 

 distance and, as if sensing this, the first hint of approaching danger 

 sends them to the cover of the lighter colored beach above. 



Concealment is the best means of protection the little birds 

 possess. It is also largely depended upon by the adults during 

 the nesting season and until the young are able to use their wings. 

 A really remarkable correspondence has been developed between 

 their color and that of the upper beaches; so perfect is it that it 

 enables them to merge themselves into and become a practically 

 indistinguishable part of the surrounding waste of sand. Hence 

 birds to be kept under observation must be watched while they 

 are in motion until they come to rest. If the eyes are diverted 

 from one after it has settled much patience is apt to be required 

 to locate it again although its whereabouts may be almost exactly 

 known. 



Their disappearance is due to the beach appearing to be uni- 

 formly of one color while actually it is not. The irregularities 

 in its surface produce everywhere a multitude of shadow-points 

 and lines and besides these shaded spots countless particles of 

 dark colored material are mingled with the lighter sand. These 

 contrasting colors are lost in the impression of sameness which 

 the beach as a whole presents and thus, while the general tone of 

 the upper parts of the bird matches that of the dry sand on which 

 it crouches, the darker markings in its plumage fade into the back- 

 ground and become no more noticeable than the lines of shade 

 they simulate. The eyes, which in the hiding bird of all ages are 

 kept alertly open, are rendered inconspicuous not, perhaps, so 

 much because they simulate shadow-points as because of their 

 likeness to dark bits of beach content. 



It is difficult to see whether or not the presence of stones or 

 pebbles is an advantage to the bird. In all probability it is; yet 

 the disappearance, at least so far as human vision is concerned, 



