3o8 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



Shearwaters in the autumn of 1896, particularly September 

 26 and October 2 and 6, apparently shows that they were 

 guided in their course by the shore-line. 



If birds are endowed with a superhuman faculty for de- 

 termining direction, why were the Shearwaters bewildered 

 when the land was hidden by fog ? Why did they imme- 

 diately resume their way when the fog was dispelled suffi- 

 ciently to reveal the landmarks ? If they had possessed 

 any directing faculty other than the ordinary faculty of 

 locating position by observing physical phenomena, it would 

 not have failed them in these instances, whether they were 

 migrating or not. The Cormorants had no difficulty in 

 finding their way in the fog to their fishing grounds in the 

 Bay and back to their rookery below Point Pinos,^ nor did 

 we experience any difficulty in finding our way without a 

 compass through the fog back to the Laboratory. The 

 Cormorants knew this bit of coast well, and so did we, and 

 we kept our bearings in the fog; but not so the Shearwaters 

 that pass hundreds or even thousands of miles of coast-line, 

 and not so the unfortunate captain who headed his ship on 

 a still foggy night the summer before directly into the land 

 two miles south of Point Pinos, supposing that he was enter- 

 ing Monterey Bay. 



The sudden coming of fog on the evening of September 

 30 may explain in part why the Shearwaters sometimes pass 

 near the south shore of the Bay when it is clear. However, 

 this short stretch of shore-line disappears with distance as 

 well as with fog. Seen from Santa Cruz on a clear day, 

 the background of mountains at Point Pinos, cut off by the 

 Salinas Valley, appears like an island rising out of the sea. 



It is significant that only species which migrate near the 

 surface of the water were observed when the land was 

 hidden from view. Perhaps those moving at considerable 

 elevation are guided by the mountain tops, which rise above 

 the low vapors, appearing from the overlooking heights as 

 islands in a sea of fog. 



iThe Murres at South Farallon, when fishing offshore, also seemed to know their 

 bearings in foggy weather. See Calif. W. B. No. Ill, p. 354. 



