An exercise in 2 colours: pthalo blue and cadmium lemon (with white, and black for the pupils).
There are blue tits nesting in the box on the front wall of our shed.
The pair spend every daylight hour flying backwards and forwards between the box and the adjoining greenhouse (where they collect bugs and spiders).
We have stacked up all manner of obstacles in front of the shed to ensure the cat cannot get anywhere near. He is well fed-up.
Unlike these birds, ours have not fledged yet.