Visit to Babel Island. 511 



fact later on to our boatman, an old birding-liand and an 

 intelligent half-caste aboriginal, by name Thomas, he in- 

 formed me that the female comes in during the early part 

 of the night to deposit her egg, and that the male bird, 

 coming in later and towards dayhght, takes the place of the 

 female upon the egg during the day, and that the outward 

 flight of birds witnessed on the morning of November 24 

 were females leaving the rookery, having deposited their 

 eggs the night previous. 



This bears out my own observations. He, Thomas, also 

 informed me thnt the male bird did not sit upon the C""- 

 during the daytime when incubation started. 



Having dissected at different times birds taken from the 

 burrows between the latter end of Noveml)er and the first 

 week in the new year, I found all birds to be females, again 

 bearing out Thomas's observations. 



Upon asking him whether the female bird sat right 

 through during the period of incubation, or if tlie male 

 bird relieved her during the night, he could not say, but 

 felt certain that the male bird came in during the night and 

 fed the female. 



Asking Thomas how he knew the male from the female 

 bird, he quickly drew forth a bird from its burrow, turned 

 the bird over, and at once diagnosed the bird as a male. 

 The morning following the depositing of an egg overnight, 

 if the bird is a female, the cloaca or entrance to the oviduct 

 is swollen and moist. If the bird is a male the vent is dry 

 and normal. If a female and carrying the egg in the 

 oviduct the sex can be detected by feeling with the fingers. 

 By dissection I proved him to be correct. 



Upon returning to camp I examined the female birds 

 placed in the barrel overnight, expecting to find the egg- 

 deposited, but the result was negative — the egg still being 

 in the same position in the oviduct. But the cloaca was not 

 so swollen as when examined the evening previous. 



In our hurry to get away from the island owing to heavy 

 weather approaching, these birds were forgotten and left in 

 the barrel. But I am thankful to say that they were not 

 left to starve, several other members of the R. A. 0. U. 



