40 Beebe, The Early Life of Loon Chicks. [f^ 



D. The arc of the swimming stroke, in the young chick, is 

 much more lateral than in the adult bird. This is difficult to explain 

 and hard to correlate with the idea that loons and Hesperornis 

 are descended from ambulatory species with more typically Avian 

 convergent hind limbs. 



E. Loon chicks can progress more easily and rapidly over the 

 ground than can the adults, in spite of the preceding conclusion. 

 Progression, however, is never by walking, but by frog-like leaps. 



F. Diving, catching fish and swallowing them head-first are 

 almost congenital instincts, much improved by practice within the 

 first week. 



G. There is no instinctive fear in these young birds. 



H. It is probable that the young loons instinctively recognize 

 the usual rolling, laughter-like call of the parents, judging from 

 their reaction to the notes of the Giant Kingfisher. 



It is interesting to compare these conclusions with several made 

 in connection with Common Terns, Sterna hirundo Linn., and 

 Black Skimmers, Rhynchops nigra Linn. These were hatched 

 from the egg and reared to maturity in July, 1903, and are now 

 living in the Zoological Park. 



A. The call, food and alarm notes of Common Terns, Black 

 Skimmers and Laughing Gulls are instinctive; not taught by 

 parents nor learned by imitation. The one positive proof of this 

 would warrant the assertion. 



B. The remarkable disparity in the length of the mandibles in 

 the adult Black Skimmer is foreshadowed even in the embryo and 

 in the newly hatched bird. 



C. My experience with a dozen terns and gulls showed that 

 these individuals prefer fresh water to salt. 



D. There is absolutely no instinctive fear of man or other 

 objects which enter quietly into the environment of the young 

 birds, but a sudden shadow or loud noise causes them to perform 

 certain acts — wholly instinctive — which have for their object an 

 escape from supposed danger. Under such conditions the terns 

 (which are not so protectively colored as the skimmers) take time 

 to run to the darkest corner or shadow before squatting, while the 

 skimmer crouches instantly, and with two or three instinctive 

 flicks of feet and legs, almost buries himself in the sand. 



