IN THE SHETLANDS 125 
these birds are concerned, there ceases to be a reason 
for thus, in idea, separating them. Let us see, now, 
how far this is the case. To begin with these kitti- 
wakes, in their courting, or rather connubial actions 
on the ledges-—_as may be seen now, but much more 
earlier in the year—both sexes open their bills widely, 
and crane about, with their heads turned toward each 
other, whilst at the same time uttering their shrieking, 
clamorous cry. The motion, however, is often con- 
tinued after the cry has ceased, and this we might 
expect if the birds took any pleasure in the brilliant 
gleam of colour which each presents to, and, as it 
were, flashes about in front of the other. The effect 
of this it is not easy to exaggerate, and if it is 
extremely noticeable to an onlooker at some little 
distance, what must it be to the bird itself, who looks 
right into the almost scarlet cavity ? We have only to 
think of the inside of some shells, or of a large, highly- 
coloured flower-cup, to understand the kind of 
esthetic pleasure that may be derived from such a 
sight. 
Similar, but much more striking, is the nuptial 
behaviour of the fulmar petrel. A pair of these 
birds lying near together, on some ledge or cranny of 
the rock, will, every few minutes, open their bills to 
the very widest extent, at the same time blowing and 
swelling out the skin of the throat, including that 
which lies between the two sides of the lower man- 
dible, until it has a very inflated appearance. In this 
state they stretch their heads towards each other, and 
