WHITE BELLIED STORM-PETREL. 151 



close-growing ice-plant. It was very unpleasant walking over 

 these breeding-grounds, which occupied considerable areas, for 

 the ground was honeycombed with burrows in every direction, 

 and gave way at each step, one's boots rapidly becoming full 

 of sand. By thrusting our arms into one hole after another, 

 we soon procured a fine series of specimens, accompanied in 

 most cases by an egg, for we had evidently hit off the breeding 

 season, and most of the birds, having laid their single egg, 

 were beginning to sit. Both sexes take part in incubation, for 

 out of twelve birds captured on the egg three were males. 

 While thus engaged we found quite a number of dead birds 

 and sucked eggs, evidently the work of the mice, as their 

 droppings were to be seen all about the burrows, and the 

 marks of their teeth upon the empty shells were unmis- 

 takable. The birds, some of which were quite freshly 

 killed and almost untouched, were invariably done to death by 

 being bitten at the nape of the neck, and in some cases part 

 of the brain had been eaten. It seemed curious that these 

 comparatively small mice should be able to kill a bird several 

 times larger than themselves, and provided with a fairly strong 

 hooked bill ; but no doubt the Petrels get caught in the end 

 of their burrow, and, being terrified, do not even try to defend 

 themselves. We obtained no young of this species, and the 

 most advanced eggs were but half incubated on the 27th of April. 

 We never heard the call of this bird ; those flying over the sea 

 during the daytime were always perfectly silent so far as we 

 heard, though they constantly passed close to our tug, and 

 there was no lack of them. When caught on their eggs they 

 uttered a short, grunting note, much like that given vent to by 

 the domestic Pigeon under similar circumstances. Our Lan- 

 zarote pilot informed us that numbers of these birds breed on 

 the Little Piton, where there are neither rats nor mice to inter 

 fere with them." 



Nest. — None. The egg being laid in a sandy burrow. 



Eggs. — One. White, with tiny reddish or purplish dots, 

 sprinkled all over the surface, or forming a zone round the 

 larger end. Axis, i 45 inch; diam., 105. 



