Foundations of the Rook's Nest. 263 
summit of hills. To the rooks their trees are their 
hills, giving security from enemies. The wooden 
houses in the two main streets are evidently of greater 
antiquity than those erected in the outlying settle- 
ments. The latter are not large or thick: they are 
clearly the work of one, or at most two, seasons only ; 
for it is noticeable that when rooks build at a distance 
from the centre of population they are some time 
before they finally decide on a site, abandoning one 
place after another. But the nests forming the 
principal streets are piled up to a considerable height 
—fresh twigs being added every year—and are also 
thick and bulky. The weight of the whole must be 
a heavy burden to the trees, 
Much skill is shown in the selection of the branches 
upon which the foundations are laid. In the first 
place, the branch must fork sufficiently to hold the 
bottom twigs firmly and to give some side-support. 
Then it must be a branch more or less vertical, or it 
‘would swing with the wind too much up and down as 
well as to and fro... Thirdly, there should be a clear 
or nearly clear space above the nest to give easy 
access, and to afford room for it to increase in size 
annually. For this reason, perhaps, nests are generally 
placed near the top or outer sides of the tree, where 
the boughs are smaller, and every upward extension 
reaches a clearer place. Fourthly, the bough ought 
not to be too stiff and firm ; it should yield a little, 
and sway easily, though only in a small degree, to the 
