NOCTURNAL MIGRATION 71 



sage which it carried to his family on Fanning, out of 

 sight below the horizon. 



Certain experiments in the homing instinct made 

 by Dr. J. B. Watson on noddy and sooty terns at 

 the Dry Tortugas Islands, off the southwest coast of 

 Florida, are highly pertinent in this connection. It 

 may be noted by way of introduction that these two 

 terns are tropical species that here occupy their 

 most northern breeding point in these seas. They 

 come to these islands from the south, and are not 

 known to wander any appreciable distance beyond 

 them to the north. 



In one case twelve sooty and twelve noddy terns 

 captured on the Tortugas, and marked to enable 

 subsequent identification, were conveyed on a ship 

 en route to Galveston, and released at distances 

 varying from 400 to 800 miles from their nesting 

 colony. Thirteen of these birds returned to their 

 nests on the Tortugas, three of them from the great- 

 est distance mentioned. These experiments differ 

 from the observations given for homing pigeons, and 

 it is concluded that these two species of terns may 

 return from a distance of 1,000 miles to their nesting 

 site, over an open sea that is supposed to be wholly 

 unfamiliar to them. Watson is unwilling to hazard 

 a statement as to the actual cause of this homing 

 ability, but it may appear that it comes from what 

 may be termed a sense of direction. It is significant 



