SOCIAL BACKBONED ANIMALS 131 
charm of their own (fig. 1103). The following vivid account 
given by Dixon (in Among the Birds in Northern Shires) will 
call up pleasant memories to the minds of many readers:— 
“And then their home in the cluster of elm-trees yonder is a 
place fraught with interest if full of noise. Towards the close of 
February, or, if the weather be still inclement, not until the 
Fig. 1103.—A Rookery 
beginning of March, and at least a fortnight or three weeks later 
than in Devonshire, the rooks begin to tidy up their big nests 
in the slender branches at the tree-tops. Others, less fortunate, 
commence to build entirely new nests. But this building is by 
no means universal for a week or more; the mania for collecting 
sticks and turf has not yet spread through the entire colony, 
and numbers of birds may be seen looking on with indifference 
at the efforts of more industrious neighbours. What a noisy 
