My eureka moment as rooks set up home in my garden

I HAVE a friend whose house is surrounded by tall beech trees.

In the trees there is a rookery which fills me with envy every time I call round. It’s not simply that I enjoy the company of rooks, I also find them one of the most interesting birds in Ireland.

But they are also one of the noisiest and a couple of weeks ago a loud burst of rook noise drew me to my hen run. I couldn’t believe my eyes. A pair of rooks was building a nest in the bare top of an ash tree that overhangs the run.

Rooks are the most gregarious members of the crow family and they nest and roost in colonies. The average mature rookery will contain anything up to 70 pairs of birds. I know where all the local ones are and they’re all several kilometres away.

But two rooks were building a nest in my garden. One bird, I presume the female, was constructing the nest and the other one was flying in with building materials. Every time he arrived there was a prolonged, noisy and apparently argumentative ‘conversation’.

It may be anthropomorphic, but it sounded as if there was considerable disagreement about how the new twig should be incorporated into the growing structure.

And it was certainly growing — a cup-shaped affair the size of two or three footballs. Did every rookery start with a single nest? Was this the beginning of a new one? Was I to be rewarded for thirty years of tree planting by getting my very own rookery? Unfortunately there has been very little sign of activity around the completed nest.

It’s possible a female rook is up there, quietly sitting on eggs. It’s too high up in the tree for me to check. But I have my doubts. Rooks seldom do anything quietly. I think it might be a dummy nest, possibly built as some sort of courtship behaviour.

There are two things that fascinate me about rooks. One is the fact that they are extremely intelligent and the other is the advanced nature of their social behaviour. These two things combined give them what I believe is the largest vocabulary of any Irish bird. I reckon I have isolated at least eighteen different ‘words’. That may not sound like a huge vocabulary, but in bird terms it is.

Not all the words are made by the vocal chords (or the bird equivalent, they don’t actually have vocal chords). They make clicking sounds, a bit like morse code, by clapping the mandibles of their beak together. They are also very into body language, bowing to each other and fanning their tails. I have spent hours trying to interpret rook language without the aid of a dictionary.

Their intelligence has only been recognised and studied quite recently. One startling conclusion that has emerged is that rooks can design, manufacture and use tools at least as skilfully as chimpanzees, despite the fact that their beaks are not as well-adapted to such tasks as a chimp’s hands.

They can take a piece of wire and bend it into a hook in order to extract a piece of food from an awkward place. In an even more extraordinary demonstration of their logical powers, a captive rook (above) was given a tube of water with a worm floating on the surface and a pile of stones. It couldn’t reach the worm but picked up the stones and dropped them into the tube until the volume they displaced caused the water to rise and the worm was in reach. That makes them about as intelligent as Archimedes.

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