322 BULLETIN 146, UITITED STATES NATIONAL MUSEUM 



In Juvenal plumage the young bird is much like the adult, but the 

 feathers of the wing coverts, scapulars, tertials, and back are tipped 

 with narrow terminal bars of " cinnamon buff " and subterminal 

 blackish bars ; those of the flanks, thighs, and under tail coverts are 

 tipped with the same color ; most of these buffy tips soon wear away, 

 and before the post Juvenal molt there? are only a few spots left on 

 the wing coverts, scapulars, and tertials, some of which are carried 

 through the winter as evidences of immaturity. I have not seen 

 enough material collected at the proper seasons to trace the molts 

 of adults. 



Food.— Mr. Dawson (1909) writes: 



Even when visiting the mainland shore, which is not often, the bird confines 

 its attention to the barnacle-covered rocko and high-lying mussel beds. Its food 

 consists of marine worms and crustaceans of various sorts, barnacles, limpets, 

 and especially mussels. Its stout, chisel-shaped beak enables it to force an, 

 entrance into the most refractory mussel shell and to sever as by a knife the 

 strong adductor muscles, which hold the valves together. Its feet also are 

 large and strong, and the toes are provided with an elaborate set of pectina- 

 tions which enable the bird to maintain a footing upon the most slippery rocks. 

 If the foothold on a sloping rock is anywise precarious, the bird retreats 

 backward and uphill by means of these convenient calks. 



A. B.Howell (1917) says: 



Certain rocky points are selected by the birds, and to these are often brought 

 the barnacles which they pry off the rocks. These are worked over at leisure, 

 and at one such depot on the Coronados, which I examined there was fully a 

 bushel of shells. 



Behavior. — The flight of the black oyster catcher is strong and 

 direct, but it seemed to me to be rather slow and heavy. Lucien M. 

 Turner (1886) says: 



The flight consists of a few rapid strokes of the wing, followed by a sail 

 for a few yards. It is sluggish when on the wing, and flies with difiiculty, 

 and rarely long continued. When alarmed it flies over the water within a 

 few yards of the shore, and in going from one point of rocks to another it either 

 makes the trip in easy stages from one large rock to another, or else follows 

 the indentations of the shore line. The bird is always on the alert, and not at 

 all shy. It generally sees the hunter long before he suspects the presence of 

 the bird. The bird either squats in a depression of the rocks, or stealthily 

 creeps to the top of some huge bowlder, where it utters a piercing, whistling 

 chatter like that of a policeman's rattle. It causes the intruder long search to 

 discover the presence of the bird, for its color is so near that of the rocks it 

 frequents that it is not easily detected. The note is then answered by another 

 bird, so that in a few minutes a dozen may be chattering hideously, making the 

 liunter wonder where all the birds came from so suddenly, as all the birds within 

 hearing assemble on the first note of alarm. 



Carl Lien says in his notes : 



If occasion requires these birds are good swimmers and, if pursued when 

 crippled, will dive deep and long. A very alert bird and always first to give 

 alarm. 



