THE BIRDS' COMPASS 



islet in the Dry Tortugas. In order that he 

 might study their habits Professor Watson lived 

 alone on the Key with them for three months. 



Birds which know nothing of man generally 

 have little or no fear of him, so Professor Wat- 

 son was soon on friendly terms with the Terns 

 of this remote island. He could go among them 

 and cause no more alarm than one would in 

 walking through a poultry yard. This tameness 

 permitted him to learn many interesting things 

 about their home lives. He also made a number 

 of tests to see whether birds which were taken 

 some distance from the Key and released would 

 return to it. 



He caught several birds and with aniline dyes 

 stained their feathers various colors in order that 

 he might recognize them. First he took three 

 Noddies. Some were set free only twenty miles, 

 others sixty miles, from the Key. All returned 

 within from one and three-quarters to about 

 three and a half hours after being given their 

 freedom. 



Then two Noddies and two Sooties, after 



