Tuesday, 9 March 2010

Nesting Rooks

Rooks are not common birds in the city, they suddenly appear when houses make way for the first grassy fields in the outskirts. Somewhat surprisingly there is a small rookery in the university grounds. Probably the large mature trees attract them. They are not present year round though. I heard a group in January and I hadn't heard them again until today. Suddenly, they have taken over the place having decided that it is nesting time. Their constant, excited drawn out single 'kaah' calls - quite different from the repeated, harder and sharper calls of the Carrion Crow - filled the air. There were at least five evident nests in construction - all of previous years nests all fell out with storms and high winds - , one just a little jumble of sticks. Rooks break off twigs and branches from trees instead of collecting nest materials from the ground, and they were coming and going from their nests to a nearby Alder where they broke off twigs for their nest. It has been suggested that collecting branches from living trees allow for better size and strength selection This description taken from Bayne, 1929 was very fitting today, with squabbles at some nests possibly as a neighbour tried to steal a precious stick.

"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." 

This series of photos taken on a few minutes illustrates the activity in the colony.
A Rook leaves its nest calling
This three Rooks were collecting sticks atop an Alder. The bird on the right has already got its stick.
This bird spend a good few minutes wandering aroung the tree undecided and left with nothing.
Bird returning with a branch
For this one a little twig will do

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