CALIFORNIA WATER BIRDS. 1 3 



the nesting- homes when summer has made them habitable.* 

 How oceanic birds rind their way to isolated islands 

 should at least receive passing notice. My observations 

 on the early southward movements ('No. I,' p. 183 et 

 seq.) show that the Dark-bodied Shearwater and other 

 highly pelagic species followed the coast-line in migrating 

 in the same manner as the Northern Phalarope. While 

 this circumstance does not prove that landmarks enable 

 the Yellow-billed Tropic Bird to reach the Bermudas 

 (Reid, Bull. U. S. Nat. Mus. No. 25, p. 263) or the two 

 migratory Cuckoos of New Zealand (Newton, Diet, of 

 Birds, p. 567; Buller, 1. c, vol. i, pp. xli, 129, 133) to 

 find their way to their winter quarters, it does prove 

 that pelagic birds are not guided by a mysterious sense of 

 direction, but by natural phenomena. To what extent 

 ocean currents and winds direct is not known, for no one 

 has studied the subject. As birds are highly sensitive to 

 changes of temperature, t the warm waters of the Gulf 

 Stream, may guide the Yellow-billed Tropic Birds until 

 the Bermudas may be sighted from a considerable eleva- 

 tion. The East Australian Current may direct the New 

 Zealand Cuckoos in their aerial voyage. 



In the report on the Procellariidae collected during the 

 'Challenger' expedition (Voy. Chal., Zool., vol. ii, p. 

 147) it is stated of the Short-tailed Albatrosses that " they 

 followed the ship every day in numbers till we got into 

 the trade-winds, when no more were observed." Per- 



* Possibly there may be a deeper insight — an intelligent appreciation of 

 the necessity of migration. The psychological aspects of migration are 

 presented at greater length in my paper in the ' Auk,' vol. xi, pp. 112-117. 



t Often in my experience in upper South Carolina has the end of a cold 

 spell been foretold by the birds when there was no apparent indication of 

 milder weather. Suddenly Carolina Wrens and other choristers of winter 

 would break the stillness with their hearty songs, proclaiming the change 

 that was soon to follow. 



