34 



HOMING AND RELATED ACTIVITIES OF BIRDS. 



may say with Exner that nothing which is done in the way of controHing the 

 behavior of a bird (or its temporary physiological condition) on the forward 

 journey affects its ability to return to its cote. 



Our own work in Tortugas has been confined largely to defining the ])roblena 

 of homing. We have had there an unrivaled opportunity to test the aljility 

 of untrained birds to home in a territory through which they have never passed, 

 and over open-water stretches many hundreds of miles in length which appar- 

 ently can offer no "landmarks." A brief account of the instinctive life of the 

 noddy and sooty tern precedes the description of our own experimental work 

 upon homing. 



Fig. 1. — Geographical situation of Tortut;as. Note the absence of land between 

 Tortugas and Galveston 



