36 WATER-BIRDS IN THEIR HOMES. 



The petrel lays but one large white egg, and the parents, as 

 we have said, share the work of hatching it. Rarely both 

 parents are found in the burrow, and more rarely still the egg 

 is found alone, yet it is still unknown which parent takes the 

 responsibility. With most birds it is the mother that cares 

 for the eggs and nestlings; but there are cases known, as 

 among the phalaropes, where the female leaves .all the work to 

 her mate. With the petrels no one knows certainly Avhat hap- 

 pens. Some naturalists report that nearly all the birds found 

 with eggs were females and others that the majority of those 

 they saw on the nest were males. 



Out of eighteen old birds that I examined one season twelve 

 were males, and there was a curious indication that the male 

 did a large share of the work. Among sea-birds it is custom- 

 ary for the female to tear off a patch of feathers from her body 

 just the size of the egg, so that the warmth of the body may 

 heat the egg directly. Often the exact number of eggs can be 

 told by the number of these "brooding spots." It is usually 

 taken for granted that the bird with these incubating spots is 

 the female ; but in every Leach's petrel that I have examined 

 during the breeding season, the male had the " brooding spot " 

 and the female lacked it. However, we must know more about 

 their habits before we can say that all the housework is left 

 for the male to do. 



Often on a sea voyage, even a short one, if it take us outside 

 of harbors, one may see the petrels following the vessel or 

 dancing over the waves in little groups. Their flight, which 

 is graceful and easy, resembles that of a purple martin; and, 

 as the birds are about the size of swallows and dark colored, it 

 would be natural to mistake them for swallows unless we 

 knew the habits of both birds. 



When they find food the petrels gather around, raising their 



