CONSPICUOUS COLOUR 31 
furze bushes. Stonechats have been observed 
for many hours at a stretch and from all 
angles, but only on very rare occasions are 
they difficult to see, as when they have dropped 
down for a moment on to broken ground after 
some insect food. They never depart far from 
their undergrowth of furze or briar, so have 
constantly at hand a secure refuge in case of 
attack, and thus do not require protective 
coloration. The usual background of this 
bird is the sky and dark bushes, not broken 
ground. 
Consider the Rook (C. Frugilegus). In the 
early morning the flock leave the woods, to 
spend the whole day in the open country, 
where they are a mark for miles around, 
especially on a day of sun, for then the flashes 
of light from their glossy plumages will reveal 
their presence three or four miles away. In 
a tree the bird is equally visible as a dark 
mass against the sky. When it is possible 
to look down on a colony of their nests, the 
sitting birds stand out blue-black in marked 
contrast to the broken brown of the nests. 
The Rook is a social bird: there is safety in 
numbers: it will be an advantage to a single 
lost bird to be able to see the flock from 
afar. 
