IN THE SHETLANDS 303 
the fish, being alive, as it probably would be, had, by 
a remarkable conjunction of two lucky accidents, 
escaped. But, on the other hand, would the herring- 
gull have dared to interfere with the skua ?—which it 
would have been doing, were the latter in the habit of 
picking up the fish from the water. On other occa- 
sions I have seen the skua fly off as soon as he had 
missed his swoop, and I have once seen a herring-gull 
following the chase, with a view, as seemed obvious, 
to such a contingency. This happened on the island, 
so that I remember it quite plainly, though, what with 
one thing and another, it got crowded out of my 
notes. 1 was, however, much interested at the time, 
for it pointed to a possibility of a further and more 
complex development of these curious parasitic rela- 
tions ; for why should not gulls become, in time, the 
constant attendants of such chases as these, on the 
off-chance merely of the skua failing to get the fish 
that he had forced the bird he was chasing to drop? 
Here would be a secondary act of piracy grown out 
of the first and more direct one. 
Herring-gulls—they are much the commonest 
species here—seem now to feed a good deal on the 
floating carcases of young kittiwakes, so I think it 
likely that the bird I twice saw doing this before, and 
took each time for a grown kittiwake, was really a 
herring-gull. It was at some distance, and I jumped 
to a conclusion without taking the trouble to verify 
it. But are these young kittiwakes first killed by the 
gulls, or found dead by them merely? As to this I 
