If you happen to live near a rookery you cannot help knowing when March has come, for, at the beginning of that month the rooks become fussy and noisy over the choosing and building of their nests. Year after year the old nests are used again, and if the birds that owned them last year have not survived the winter, others will seize them. Then there are quarrels and fights, for more than one new couple are sure to want each free nest. It may be that they are lazy about building new nests, or that they know that the old nests are on the best and safest sites (which is very likely, because founders of the colony would be careful to choose the most suitable forks for their cradles), or that they feel that it is important to win the homes of their great ancestors. But, in any case, the possession of the old nests is always settled before any new ones are begun. Sometime a pair will pull an old nest to pieces and build another in its place. Presumably they have found that the winter storms have so loosened the structure that it would be a waste of time to repair it, or at any rate that it would be safer to rebuild it. That they are able to reach such a conclusion suggests that they can apply reason to the solution of a problem and communicate their ideas on the subject, one to another. They have not only to decide to rebuild, but also to agree not to adopt the simpler plan of constructing a new nest on a fresh site.

Most birds do their nest-building quietly and as secretly as possible. But the rooks cannot hide theirs, so they talk about them freely. Every time they come back with a twig they shout the news to the whole rookery and to any one else who may be able to understand them. But it is dangerous for them to boast too much about a stick, for it may be stolen by a neighbour when they are gone to fetch another.

The winter storms bring down many twigs and the rooks make use of these. But if twigs are scarce and the wind does not happen to be obliging, the rooks will break some from the trees themselves. This saves the time spent in searching and fetching; but it means more than that. There may be plenty of twigs on the ground, but they may not all be suitable and it will cost time and trouble to make a selection from them, whereas it is easy to go to a whole tree-top of them and choose those that will best serve the purpose. But further, the twigs on the ground are mostly old and dry, while those on the trees are strong and lithe and so well fitted for weaving.

I have noticed this done chiefly when the birds are beginning new nests, and it has occurred to me that they use these young, straight, and unbranched shoots specially for building the foundations, as they may be so readily twisted about the branches of the fork. Later, when a stout base has been formed in this way, sticks from the ground may be brought and built up on it to complete the nest.

It has been said by some observers that the rooks always break twigs from trees some little distance away from the one in which they are building, and certainly if there is a lime tree within easy reach they will take what they want from it, for the shoots of the lime are long and withy. I have myself, however, watched a rook taking material for its nest from the elm in which it was adding one more home to an old colony. It simply sailed round to the other side of the tree, broke off a twig, carried it to the fork chosen for the nest, placed it in position, and then returned for another, and this it repeated several times within a few minutes.

I was able to observe its action through field-glasses, and I noticed that it grasped the shoot close to the branch with its beak and wrenched it off, as we do, by bending it sharply from side to side. Each time it stood over its task, but sometimes a rook will seize a twig from below and add its weight and the leverage of its flapping wings to the powerful jerking of its neck.

The rook is not the first of our birds to nest—the raven begins in February and so does the crossbill—but, apart from exceptional blackbirds and thrushes, it is the earliest of those we all know well. A few follow suit as March advances, but the majority wait until April or May. While this busy season is in progress observers cannot fail to be impressed by the wide divergences in the habits of the various species, even of those that are closely related.

[on nest linings] There is not a wide difference between a rook and a carrion crow, yet if you were to find a solitary rook's nest and a carrion crow's on neighbouring trees, you could at once tell which was which by the lining. The rook's nest is lined with rootlets and the crow's with rabbit's fur. [snip]

Why is it that the wilder, more savage carrion crow has varied towards luxury, whereas her social and almost civilised cousin the rook has won success in the struggle for existence only by strict adherence to severity?