PKIBILOF SANDPIPEK 157 



between these feathers, the latest being of an almost even shade of pale 

 plurnbean with darker centers and generally with a narrow white margin. 

 There are no specimens to show the complete change, but it is probable that 

 these young birds remain on the islands until it is completed. By the middle 

 of June the adults have fully changed to the breeding plumage, but on some 

 specimens a few feathers of the previous winter's plumage persist much later. 

 Thus on many specimens some alternate feathers of the scapulars and tertials 

 are of the previous winter's well-worn plumage. In fact, few specimens are 

 free from these old feathers. Soon after the middle of July the new plumage 

 of the next winter begins to appear. At first a few feathers show about the 

 breast, then on the scapulars, thence up the neck and over the head, so that 

 by the 10th of August they have changed one-half. It would thus appear that 

 before this species leaves the islands they assume entirely their new dress. 

 And at this season, August 10, old and young flock together for the first time, 

 and confine themselves to the sand beaches and surf margins about the islands 

 for a few weeks, when they take flight by the 1st or 5th of September, and 

 disappear until the opening of the new season. 



The Pribilof sandpiper is much paler in the ju venal plumage and 

 grayer in the winter plumage than the Aleutian. 



Food. — Preble and McAtee (1923) report on the contents of 192 

 stomachs, as follows : 



The articles of food composing more than 1 per cent of the total were: 

 Mollusks, 32.63 per cent; crustaceans, 29.15 per cent; flies (Diptera), 23.49 

 per cent; beetles, 10.29 per cent; marine worms, 1.27 per cent; and vegetable 

 matter, cbiefly algae, 1.21 per cent. The vegetable matter, besides algae, in- 

 cluded bits of moss and a few seeds of grass, lupine, violet, crowberry, and 

 bottle brush. 



Behavior. — Referring to the habits of Pribilof sandpipers, Mr. 

 Palmer (1899) says: 



They appear stupid when solitary and without a family, and will stand per- 

 fectly still, eying one from a little eminence. Occasionally we are startled 

 by a loud druuett from the side of a sand dune, and I was at a loss for some 

 time to discover the owner of this most unmusical sound, which finally turned 

 out to be an individual of this species standing motionless and watching us. 

 It would seem impossible for this sound to have issued from this bird if I had 

 not seen it in the act. These sandpipers have the habit in common with others 

 of their kind of suddenly elevating the wing directly over the back. Often 

 when alighting on the tundra, as soon as they stopped up went one wing, fol- 

 lowed soon after, perhaps, by the other. Often while watching a flock on 

 the lagoon beach first one would elevate a wing, then another; it was always 

 the near wing which went up first. I never saw a bird elevate the off wing 

 first. I know of no reason for their doing so. They are tame. I have walked 

 up to a flock of about 50, and with care could drive them before me for some 

 distance before they took flight, being but a few feet away. They are often 

 seen feeding in the water up to their breasts, and seem to take delight in it. 

 They swim readily, but not often. On June 30 1 saw one fly out to a stone 

 in a pool, and after gathering all the food possible it deliberately swam to 

 another, and having visited each stone in the same way flew back to the shore 

 and then bathed itself, occasionally taking a swim. 



