We've just returned from the south of France near the Spanish border. At night when walking on the promenade , huge flocks of very noisy birds were hiding in the trees - in fact the trees seemed almost alive - but we couldn't actually make out the birds in the light. We came across the same thing in the city 20 odd miles inland a few days later by the river. Can anyone tell me what they might be? Sorry I can't give more info but I really could only hear them and not see them at all. They must be there quite regularly though as the pavement below the trees was covered in crunchy droppings. Thanks in advance.
They're starlings, a common sight this time of the year in Southern Spain and the Balearics, even the locals turn out to watch the huge flocks wheeling about in the evening sky.
Thank you so much to everyone who answered. I'm pretty sure now I've looked things up that were in fact starlings - it was such a interesting phenomenon though which I thoroughly enjoyed witnessing (once I was out of the firing line..!) Thank you again.