692 ARCTIC OR RICHARDSON’S SKUA. 
being entirely sooty, while the other has light undeyr-parts ; but 
where they meet they mate indiscriminately. Both the extreme 
and intermediate forms are found nesting on our northern islands, 
the Feroes, Iceland, the coasts of Scandinavia, Russia, and probably 
Novaya Zemlya; but the sooty bird has seldom been observed in the 
Spitsbergen group, and most of the specimens from the far north of 
America are white-breasted. The dark form predominates towards 
the southern limit of the bird’s breeding-range, whereas the white- 
breasted race increases in numbers to the northward until it gains 
the ascendency. As a breeding-species this Skua may be described 
as circumpolar ; in the cold season it frequents the coasts of Europe 
down to the Mediterranean, West Africa as far as the Cape of Good 
Hope, the Persian Gulf and Mekran coast, the North Pacific to 
California, and the Atlantic to Barbados and even Rio de Janeiro, 
while it has occurred several times in Tasmania and New Zealand. 
Towards the end of May or early in June the eggs, 2 in number, 
are laid in a hollow of the moorland moss or grass; they are of a 
brownish-green colour, blotched with dark brown: measurements 2°4 
byr‘6in. The flight of this Skua is rapid, although somewhat devious; 
and any intrusion upon the breeding-ground is resented by swoops 
which are directed from behind or sideways; but although the bird 
will actually strike with its wing, I have never seen it make a front- 
attack. The cry is a plaintive mee, sometimes a sharp mee-dwh. 
This species feeds principally upon fish, obtained by robbing the 
smaller Gulls, but it also preys upon wounded or disabled birds, is 
said to plunder the eggs of other sea-fowl, and has been known to 
pick up worms and molluscs. It does not dive, but has frequently 
been observed to settle on the water. 
The lowest figure is that of an adult though, but not a very mature 
example of the intermediate form; in many, as already observed, 
the throat and breast are white, and not shaded with brown. The 
middle bird may be said to belong to the dark race, though more 
sooty individuals are to be met with. Between the above there is 
every gradation; but all the adults have a yellow tinge on the 
acuminate feathers of the cheeks and neck, and are umber-brown 
on the upper-parts. Length 20 in. (tail 5, and central pair of 
feathers often 3 in. longer), wing 13 in. The young bird (at the 
top) I consider to be the offspring of light-coloured parents; the 
progeny of a dark pair being much more sooty, with merely rufous 
edges to the upper feathers. 
