300 THE ZOOLOGIST. 



weigh four or five pounds, and this weight striking a, man on the 

 head, and coming at such a velocity, would certainly kill him. 



In every case in which a pair of Great Skuas were seen 

 together, as if nesting, one bird was dark and the other light 

 coloured, and the inference was that the colours might be sexual. 

 For three days I was frequently among them, and having con- 

 sulted the few books at hand, and finding no mention of this 

 easily-observed difference in colouring, a dark bird was shot on a 

 portion of Foula remote from the breeding grounds, and next day 

 a light one was procured in another part of the island also at a 

 distance from the breeding grounds. The dark bird turned out 

 to be a male and the light one a female. The dark one was 

 rather smaller, with bill and claws not so stout as in the light 

 bird. Whether the colouring is associated with age or sex, or 

 merely a phase which both sexes may present, as in Kichardson's 

 Skua, I cannot say. The fact that the dark bird is smaller may 

 have been accidental, for the difference in size was not detected 

 when the birds were sitting or flying past ; but if not accidental, 

 and constant, the stouter and older-looking bill and claws in the 

 light Skua is in favour of the age theory. Then the fact that a 

 dark bird seemed always paired with a light one, and that they 

 were about equally numerous, is in favour of the sex theory ; and 

 lastly, the fact that in one or two cases the distinction in colour 

 was not so decided is in favour of the phase theory. When the 

 Skuas were sitting on the ground, side by side, the difference in 

 coloration was in every instance noticed. 



When on the steamer going to Shetland, a gentleman, who 

 said he knew it well, told us that there were only two pairs of 

 Skuas now left on Foula. We heard later, however, that eighty- 

 four pairs bred there last year, and this year we ourselves saw 

 between seventy and eighty pairs. By three different old men on 

 the island I was informed that when they were boys the "bonxies" 

 were not nearly so numerous as at present ; that the proprietor, 

 Mr. Scott, of Melby, protected them, and they increased greatly, 

 but that for the last four years they have been diminishing in 

 numbers. This is no doubt due to the fact that the Foula men 

 themselves have become egg-dealers, and have been supplied with 

 egg- drills, &c, for blowing, and that they take all the first batch of 

 eggs laid and most of the second. Last year the " bonxies " did 

 not get away with their young until August, and then only a few. 

 Besides this persecution, I was informed that an excursion 



