460 STERCORARIIDAL 
ARCTIC SKUA. Stercorarius crepidatus (J. F. Gmelin). 
Coloured Figures.—Gould, ‘ Birds of Great Britain,’ vol. v, pl. 80; 
Dresser, ‘ Birds of Europe,’ vol. viii, pls. 611, 612, fig. 2; 
Lilford, ‘ Coloured Figures,’ vol. vi, pl. 34; Booth, ‘Rough 
Notes,’ vol. iii, pls. 43-46. 
Of the four species of Skuas which migrate during the 
colder months! to British waters, this species, also called 
Richardson’s Skua, is by far the most plentiful. It visits 
the east side of England in larger numbers and with much 
greater regularity than the west, while all round the Scot- 
tish coast it is by no means scarce. Moreover, a goodly 
number remain to breed in Sutherland and Caithness, and 
there are colonies on the Shetlands,” Orkneys, and Hebridean 
Islands. 
It has been more often recorded from the waters which 
surround the Irish coast than any of its three congeners. 
Still it can be regarded only as a periodical, not an annual 
visitant. On its northern passage 1n spring, it is less often 
seen; Mr. Warren has observed it in the month of May, 
chasing Terns at the estuary of the Moy, on the Mayo 
coast. Here the birds have been noticed to tarry for some 
days en route for their breeding-haunts. Several were seen 
on Donegal Bay, and one secured there on May 18th, 1881, 
by Mr. E. W. Holt. Mr. Ussher, in his ‘ Birds of Ireland’ 
mentions instances of the occurrence of this bird in June. 
Like the Pomatorhine Skua, it has made exceptionally 
large visitations from time to time to our coasts. In- 
teresting accounts have been cited by Mr. Warren, among 
which may be mentioned a large migration witnessed in 
October, 1851, at Killala Bay. Small flocks were seen pass- 
ing in succession in a south-westerly direction until the 
total number amounted to about a hundred birds. 
Flight. — This Skua, when pursuing Gulls and Terns, 
displays the same adroitness in turning and swooping which 
so well characterises the whole group. At all times the 
flight is exceedingly buoyant and well-sustained. A Gull is 
‘ After October this Skua becomes rarer on our coasts. Mr. Saxby 
mentions seeing one on November 28rd, 1902, while several more were 
ohserved on the east side of the Shetlands up till December 6th, 
(‘ Zoologist,’ 1903, p. 157). 
2 Mr. Eagle Clarke states that on Fair Isle, one of the Shetland 
Group, this bird, which formerly bred in some numbers, is now reduced 
to a single pair (Ann. Scot. Nat. Hist., 1906, p. 79). 
