SULE SKERRY, ORKNEY, AND ITS BIRD LIFE 25 



sound they were making I don't think they were more than 

 200 yards distant. I never saw or heard them during the 

 day-time in September. 



The Oyster-catcher is a very regular visitor, making its 

 appearance every year about the end of February. From 

 30 to 40 pairs annually rear their young, laying 3 eggs 

 in 1902 I found 6 nests with 4 eggs in each in June. 

 When the young are able for the journey they all disappear, 

 generally about the end of September. 



A very interesting visitor is the Stormy Petrel (Pro- 

 cellaria pelagica). It is not an easy matter to fix the exact 

 date of their arrival, for they are never seen during the day, 

 and it is only by going out amongst the rocks at night that 

 one can both see and hear them. On a clear night in June, 

 between 1 1 P.M. and midnight, I have often sat amongst 

 the rocks watching them flitting around in hundreds, very 

 like Swallows in their movements. They lay in holes in 

 the ground and under stones, and about the only way to 

 find their nest is by listening for their peculiar cry, which 

 they keep up the whole night that is to say all the time 

 darkness lasts, for at that time the night is of short duration. 

 They lay about the ist of July, but I have got an egg 

 quite fresh on the ist August. However, the former day 

 is the general time, for about the 1st August, by listening 

 at night near their haunts, one can hear the young birds in 

 all directions making a cry very similar in sound to the 

 plaintive call of the progeny of the domestic fowl when 

 they have lost sight of their mother. Like their arrival, it 

 is difficult to fix the date of their departure. I have got 

 young birds on the lantern in November. It is a common 

 belief that these birds feed entirely on an oily substance 

 skimmed off the surface of the sea. I can testify that they 

 believe in something more substantial. It is quite common 

 on dark nights in November to see 5 and 6 on the lantern, 

 and almost without exception the first thing they do after 

 alighting they rarely dash against the windows, just rest 

 carefully on the trimming pathways is to vomit everything 

 in their stomach. I have, scores of times, sat inside the 

 lantern room, with a 90,000 candle power light shining 

 on the bird, and seen it disgorge pieces of half-digested 



