PURPLE SANDPIPER 149 



Adults have a complete postnuptial molt between August and 

 November and a partial prenuptial molt from January to May; 

 this latter involves most of the body plumage, but not all of the 

 scapulars, back, rump, or upper tail coverts. 



Food. — The favorite feeding places of purple sandpipers are the 

 wave-washed rocky shores of islands or promontories along the 

 seashore, with a decided preference for islands. Here, where the rocks 

 are fringed with rockweed, waving in the restless waves, or covered 

 with barnacles and various slimy products of the sea, these sure-footed 

 little birds are quite at home on the slippery rocks, as they glean 

 abundant food at the water's edge and skillfully avoid being washed 

 away. Yarrell (1871) says that — 



it may be seen busily employed turning over stones and searching among 

 seaweed for the smaller shrimps and sanilhoppers which are to be found there, 

 and it also feeds on young crabs, marine insects, and the soft bodies of animals 

 inhabiting small shells. 



Witherby's Handbook (1920) gives its food as — 



varied, including insects: coleoptera (Otiorhynchus) , diptera (larvae of 

 Chironomus) , also spiders, Thysanura (or Collembola) , annelida and Crustacea 

 (Amphipoda, Isopoda, Orchestia, Idotea, Gammarus, and Podocerus) as well 

 as mollusca (MytUus, Littorina, Purpura, etc.)- Vegetable matter is also eaten 

 including algae, grasses, moss, buds, and leaves of phanerogams and remains 

 of cryptogams. Seeds of Cochlearia have been identified and small fish (Gobbus) 

 nearly 1 inch long, as well as ova of lumpsucker. 



Behavior. — The flight of the purple sandpiper suggests at times 

 that of the spotted sandpiper, for when disturbed singly along the 

 shore it is apt to fly out over the water with rapid downward wing 

 strokes and, describing a large semicircle, return to the shore some 

 distance ahead. When flying in a flock the birds are often closely 

 bunched, the whole flock wheeling and turning in unison, showing 

 alternately their dark bodies and their white bellies, in true sand- 

 piper fashion. As a rule they do not make very long flights or fly 

 very high. Their migrations are short and deliberate. They arc 

 rather sedentary birds and can generally be found in certain favorite 

 localities all winter and year after year. But, as they show a de- 

 cided preference for the outer sides of surf-swept ledges, they are not 

 often seen from the land. They can swim almost as well as phala- 

 ropes and in calm weather they will often alight on half sub- 

 merged seaweed or on the surface of the water. Dr. Charles TV. 

 Townsend (1905), who watched a flock on an island off Cape Ann, 

 describes their actions as follows: 



They finally alighted on a steeply sloping rock close to the water's edge on 



the northeastern point of the island so that they could be watched with 



binoculars and telescope from the shore. Fifty-eight birds were in sight 



and there were fully half as many more on the other side of the rock, hidden 



54267—27 11 



