Perhaps wild rooks are not presented with a need to use tools, and so don't bother.
And, although New Caledonian crows, which also make tools in the wild, can manage the hookmaking trick, wild rooks are tool-using virgins.
The opening session talked less of goslings and rooks than of an animal that was one of Tinbergen's favourite toys the three-spined stickleback.
"Rooks nesting high, it's bound to be dry, " Mr Eavis says confidently.
BBC: NEWS | Entertainment | Festival boss puts problems in past
The researchers believe that while rooks had the ability to cooperate, they may have failed to understand the importance and value of the act.
But Elinor Rooks, a member of the campaign to save Withington baths, said the historic baths had been modernised and local people were angry at the closure plan.
The weather has a big impact on the festival, whether it is a mudbath or dustbowl - and Worthy Farm's rooks have given Mr Eavis hope for this year's outlook.
BBC: NEWS | Entertainment | Festival boss puts problems in past
The visitors have won their last five matches, while the Rooks last tasted success in a league fixture back in April with back-to-back Blue Square Premier wins against Altrincham and Weymouth.
Three men in Ralph Lauren jeans and telnyashki, the distinctive striped shirts that paratroopers often continued to wear after they quit the army, trailed after him, shotguns cradled in the rooks of their arms.
"Sympathetic concern" has also been observed in gorillas, bonobos, dogs and even rooks - but it is the calming effect that it had on the Chester Zoo chimps which is said to be a new observation.
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