206 LONG-WINGED SWIMMERS — LONGIPENNES. 



close examination shoAved that two parallel strata of sandstone projected irregularly 

 from the face of the cliff for a distance of from one to four inches, and that the nests 

 were built where these broken ledges afforded a partial support, although the shelf 

 thus originated was seldom more than half as wide as the nest. The line of nests 

 followed the winding projections of these ledges, the material used being dry grasses 

 agglutinated together, and also secured in the same way to the rock. Each nest had 

 a very shallow depression at the top, in which were two eggs. The Avhole had an 

 intolerable odor, and the nests were very filthy. The birds hardly moved at the 

 approach of an intruder ; only those within a distance of a few yards left their posts. 

 Mr. Dall took away a nest containing two young ones, and the parent bird, coming 

 back soon after, was astonished at their mysterious disappearance, and evidently sus- 

 pecting foul play on the part of her nearest neighbor, began a furious assault upon 

 the latter. A few eggs were obtained in a moderately fresh condition, but most of 

 those seen were far advanced toward hatching. 



Mr. Dall adds that the Kittiwake manifests great curiosity, sending out scouts 

 whenever any unusual object approaches. If not molested, these scouts soon return 

 to the flock, and tlie whole then proceed to investigate the phenomenon. This bird 

 is described as having a shrill, harsh cry as well as a low whistle, the former being 

 the one generally uttered when it is alarmed, and the latter being addressed to their 

 young, or used in communication with each other. After the young are fully fledged 

 the parent birds leave the harbors, and are found during winter off shore, except in 

 heavy storms. 



At Delaroff Harbor Mr. Dall found the nests attached to the sides of the bare 

 rocks and pinnacles of scoriaceous lava near the entrance. The slight ledges and 

 projections being so small as to be invisible at a short distance, the nests ai)peared to 

 be fastened, like those of the Swallow, to the perpendicular faces of the rocks ; and 

 the appearance they presented was very remarkable. 



In building its nest — as Mr. Elliott states — this species uses more grass and less 

 mud than the hrevirostris, and its eggs are more pointed at the small end than those 

 of the last-named bird, the ground-color being also lighter, with numerous spots and 

 blotches of dark brown. The chicks cannot with certainty be distinguished from 

 those of the hrevirostris until two or three weeks have elapsed after they have been 

 hatched. 



The eggs of the Pacific variety — collected from Round Island, Alaska, by Mr. 

 Dall, and from the Prybilof Islands by Mr. Elliott —vary in length from 2.20 to 2.3;') 

 inches, and in breadth from 1.60 to 1.65. The ground-color of some is a pale brownish 

 gray, that of others is a pale greenish gray. The markings are more or less scattered, 

 are rather faint, slightly longitudinal and zigzag in their shape, of lilac-gray, mingled 

 with other markings of a dilute umber. The eggs are somewhat uniform in their 

 appearance, and do not exactly correspond Avith any of the common R. tridactyla 

 which I have ever met with. But this variation, although thus constant, is not 

 greater than that which has been found to occur in other instances in eggs of the 

 same species taken at different localities which were at some distance from each 

 other. 



