BOOBY AND MAN-O'-WAR BIRD 



215 



A Booby Family 



that either there was a marked difference in the develop- 

 ment of the embryos or that one or both eggs were infertile. 

 For example, of thirteen nests containing two eggs, in three 

 nests both were bad, in ten both were good but with every 

 good pair there was about a week's difference in the age of 

 the embryo. In six nests each containing one young and one 

 egg, five of the eggs were decomposed. 



With those Boobies which lay two eggs, apparently a 

 week intervenes between the deposition of the first and sec- 

 ond egg, and to this unusual irregularity in connection with 

 the high percentage of infertility, we attribute the discrep- 

 ancy between the number of eggs laid and the number of 

 young reared. 



Our studies were not sufficiently prolonged to enable us 

 to determine whether, when both eggs were fertile, the 

 young first hatched survived or whether, through continued 

 incubation of the remaining egg it starved and the young 



