The sky overhead is blue this morning: lavender blue overhead, shading through cornflower and azure - possibly cerulean! - towards the white gold glitter of the rising sun. There are house martins whizzing and squeaking in all that blue, white undersides catching the sun. They crisscross the sky quite randomly, then get sociable and start wheeling - some clockwise, some anticlockwise. Then they all whizz off again.
That summer I spent in Andalucia, there were lots of martins living in the eaves of the barn. In the mornings they would assemble in gossiping hordes on the telephone wire that ran from barn to house, taking turns to throw themselves into the air, swooping and diving in all directions. In the late afternoons we would see them flitting about, warming up like joggers, and then they would skim across the swimming pool, scooping water in their beaks.