44 The Wilson JJulletix — No. 55. 



cult to find, and the finer spotting of the eggs renders them less 

 conspicuous in the shade of the grasses. 



Onlv two nests were studied to the completion of the incu- 

 bation period, but these had an incubation period of 21 days. 

 In general the habits do not difi:'er from those of the Common 

 Tern. Their instincts inclined them to be more wary, but 

 they were more courageous when their nests or young seemed 

 in danger. yVn outraged pair would even follow the intruder 

 from one of the Woepecket islands to the other, fighting all 

 the way. 



THE PLUMAGE OF S. HIRUXDO AND DOUGALLL 



Anv such study would lack completeness that did not men- 

 tion the plumages of the downy young and the young birds 

 in their first definitive feathers. 



The downy young of hirundo is mottled wdth tawny and 

 black or dusky, the mottling varying within small limits with 

 the individual. The wdiole throat is dusky, but the rest of the 

 under-parts are pure white. The expanded, flufify down 

 leathers form a complete covering for the body, but they grow 

 only in the feather tracts which are characteristic of the terns. 

 Figure 4 illustrates the pattern of mottling. This pattern 

 seems particularly well adapted for the concealment of the 

 chick among the rubble of the beach or upon the drift seaweed. 

 On the gray sand or among the yellowish grass, however, the 

 young is readily detected because its colors are here contrasty. 

 While the }'oung remain in the nest they seldom show fear, 

 but raise their heads and open their mouths for food. 



The downy young of dougaUi are tawny streaked with 

 dusky. One could not confuse this pattern with that of the 

 downy young of Junindo. The legs of the young hirundo are 

 coral red or lighter, while the legs of the downy young dougaUi 

 are invariably almost black. The streaked pattern of the 

 dougaUi chick renders the bird almost invisible in the grass 

 covered nest. The young of doitgalli flatten themselves down 

 into the nest in apparent fear upon the approach of an intruder. 

 \^^hen they leave the nest they hide away under the grass. 

 Their difference in color pattern seems to go with a difference 

 in disposition. 



