Expedition to the Eastern Canary Islands. 69 



morning. If, however^ tliey have been out to sea througli- 

 out the day, they return to land about an hour after dark- 

 ness has fallen (i. e. about 8 p.m.). As soon as they begin 

 to come in they commence calling — a long drawn-out wailing 

 note repeated several times, and often ansvrered fiom within 

 the ground by a peculiar purring sound, which I imagine is 

 made by their mate. The birds would fly round several 

 times in lessening circles close above the rocks, eventually 

 settling at the entrance to their particular hole. It is then 

 possible, by noiselessly creeping over the rocks and suddenly 

 switching a light into their eyes, to approach within striking 

 distance of the birds. Occasionally, while sitting amongst 

 the rocks with lights extinguished, it is possible to " hook " 

 a bird as it glides close overhead. The fishermen are remark- 

 ably adept at catching them in this way, although I should 

 imagine that the method is seldom employed. 



By June the 7th, the day on which we left Graciosa, 

 nesting had become general, and all the birds had eggs. On 

 Montana Clara even better opportunities for studying the 

 habits of these Shearwaters were afforded me, but for the 

 nesting-sites chosen by the birds on this island, I must refer 

 the reader to page 80. Although over a hundred birds 

 were caught (the majority being again liberated), I never 

 once found more than one bird in the hole at a time. Both 

 males and females were taken on the eggs, in about equal 

 numbers ; the sex of the sitting bird is easily distinguish- 

 able, as the male has a much more formidable bill than 

 the female. Only one egg, of course, is laid, and all varied 

 tremendously in shape and size. The measurements will be 

 found under this species in the annotated list (see Part II.). 

 In many cases a perfectly formed egg, completely shelled, 

 was taken from the oviduct of a dead bird. 



The Shearwaters called during all hours of the night, but 

 seemed particularly noisy at about 3 a.m., at which time I 

 believe many went out to sea. I think there is no doubt 

 that they take it in turns to sit on the egg, the male 

 feeding while the hen is sitting and vice versa. If pulled 

 out of their holes in the daytime they seemed completely 



