34 



HOMING AND RELATED ACTIVITIES OF BIRDS. 



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

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

 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 Tortugas, Note the absence of land between 

 Tortugas and Galveston 



