402 



TEE POPULAR SCIENCE MONTHLY 



Fig. 



Noddy Gulls nesting on Bibd Key., Tortcgas. 



so doing is quite shy, but if an egg be placed in the nest the mere sight 

 of it causes the bird to lose all shyness, and it sits upon the egg as if it 

 were its own. Both male and female cooperate to build the nest, but the 

 male alone procures food for both during this period, the female con- 

 stantly guarding the nest. After the egg is laid, both male and female 

 fly away to fish and take their turns in brooding the egg at intervals of 

 about two hours. The egg hatches after 32 to 35 days. But the noddy 

 gull does not recognize its own egg, but will readily incubate the egg of 

 the sooty tern or any object colored or uncolored bearing more or less re- 

 semblance to an egg. It recognizes the locality of its nest however, and 

 returns to the old locality if the nest be moved, but it will accept an 

 artificial nest placed in the old nest locality without hesitation. Dyeing 

 one of the mates in strange colors causes the undyed bird to attack it, 

 and indeed all other birds upon the island displayed excitement at the 

 appearance of a dyed bird. 



The sooty tern nests upon the ground, and recognizes the exact lo- 



