44 HOMING AND RELATED ACTIVITIES OF BIRDS. 



18 days: 



Noddy No. 16. Released at 9 h 30 m a. m., 18 days in captivity. Refused at first to 

 leave dock. When driven away started north after bathing. Was not observed 

 at nest until 6 days later. He was then sitting on the rim (at 5 a. m.). Mate was 

 near. Nesting activities not resumed. Probably on Bird Key on night of day 

 released, but left for feeding-grounds every morning before observations could be 

 made. 



Noddy No. 19. Released same hour as No. 16. On release joined No. 16 in 

 flight. Seen near nest on following morning. Nest not resumed. Mate had 

 completely deserted. 

 20 days: 



Sooty No. 7. Released 8 h 50 m a. m. after 20 days. Bird very weak. Would not leave 

 Loggerhead and finally died there. 



Sooty No. 8. Released as above. Flew off and headed north. Never appeared 

 at nest. 

 23 days: 



Noddy No. 20. Released 3 h 31 m p. m. after 22 days. Flew north. O had taken 

 another mate. R was not observed until 3 days later (probably was driven off 

 byO). When observed R was not sitting egg. Nest was finally abandoned. 

 %5 days: 



Noddy No. 13. Released 8 a. m. after 25 days. Not observed at nest until 3 days 

 later. Made no effort to sit egg. O not near nest. 



Noddy No. 14. Released with No. 13. Spent 5 minutes in water, then flew 

 west. In good condition. Not observed until 3 days later. Mate not near. Made 

 no effort to sit egg. 

 26 days: 



Noddy No. 15. Released 11 a. m. after 26 days. Spent 5 minutes in water, then flew 

 west, appearing at nest at 12 h 30 m p. m. Was not sitting on egg. Two days 

 later was observed sitting on limb above mate. Mate was on the egg. Later 

 observations showed that O had accepted another mate. R often appeared and 

 hung around, but never forced out the intruder. 



A summary of these field notes is given in table 6 : 



TABLE 6. 



No. 11 at end of 11 days returned to nest. 

 17 at end of 15 days returned to nest. 

 16 at end of 18 days returned to nest. 



19 at end of 18 days returned to nest. 



20 at end of 22 days returned to nest. 



No. 13 at end of 25 days returned to nest. 



14 at end of 25 days returned to nest. 



15 at end of 26 days returned to nest. 

 18 did not return to nest after absence 



of 16 days. 



None of the 4 sooties living through the experiment returned to the nest. 

 Except No. 11, the relations with mate were not resumed. 



From this series of notes we see either that the conditions were not favorable 

 to the sooties or else that locality and nesting habits are not retained by them 

 for as long a time as by the noddies. From data offered below it would seem 

 that the unnatural conditions offered by captivity at Loggerhead produced 

 a waning of the nesting impulses, if not loss of retention of nest locality, and 

 furthermore, that habits of responding to a given mate are lost before the habits 

 of responding to a given nest (place) . The system of observation at the nest, 

 however, had not been perfected. When hundreds of nests were under obser- 

 vation by one investigator, it might easily have been possible for him to have 

 timed his observations in such an unfortunate way as to have missed the ap- 

 pearance of the Rs at the nests. A reference to page 42 shows that the sooty 

 when not brooding the egg disappears for 24 hours and sometimes 48. Fur- 

 thermore, these birds usually leave their nests at daybreak, before there is 

 sufficient light for identification. 



