( 232 ) 

 ON THE NESTING OF THE STORM-PETREL. 



BY 



AUDREY GORDON. 



On July 2nd, 1919, after waiting many days for the weather 

 to moderate sufficiently, a companion and I sailed out to one 

 of the smaller islands of the Inner Hebrides group and 

 remained there till July 15th. This particular island is about 

 one and a half miles long and half a mile broad, and rises to a 

 height of 300 feet. It is composed of terraced basalt, and the 

 coast-line is much indented with not too precipitous cliffs, 

 forming an ideal nesting haunt for all kinds of sea birds. 



On July 2nd, about half the Storm-Petrels {Hydrobates 

 pelagicus) had laid, but all the eggs I found were evidently 

 quite fresh. A great many pairs seemed to be still mating. 

 They were present in aU suitable situations all over the island — 

 old broken walls, among big boulders and under heaps of round 

 sea-worn stones, in some places a few feet above high tide 

 mark, and in others as much as 100 feet above the sea. The 

 easiest way to find the birds is by their strong peculiar smell, 

 quite different from the smell of Puffins {Fratercnla a. grabce), 

 which are occasionally found nesting among the Petrels. 



On bright, sunny days the birds rarely make any noise in 

 the nesting holes, but on dark, cloudy or misty days one can 

 often locate them by their purring note, " Purr-r-r-r-r- 

 chee-ka " repeated incessantly ; I heard this note kept up 

 without a break one night for over an hour. I think there 

 is no doubt this is the mating song, although it is apparently 

 made by both cock and hen. During the first week of July I 

 frequently found both birds together in the nesting crevices, 

 and often both " purred." 



Our tent was pitched close beside a long beach of piled up 

 round stones, under which some twenty pairs of Petrels were 

 nesting, or about to nest, so we had a good opportunity to 

 observe their nocturnal habits. They usually appeared first 

 about 10.30 p.m. G.M.T., having gradually become more 

 noisy from sunset onwards. On calm nights they did not caU 

 at all while flying, but on dark and stormy nights, or if misty, 

 the noise of their calls was most weird. This flighting note 

 is entirely different from the " purring " note — it is very loud 

 for the size of the bird, and is quite unlike the sound produced 

 by any other bird, as far as I am aware. The nearest rendering 

 I can give in words is — " Cuch'-ah, cuch'-ah, cuch'-ah, coo'-ah," 

 the accent being on the first syllable. It is very husky, and 

 sometimes ends in a sort of shriek on a high note. As far as 



