Birds and others use structural trickery to produce vibrant blue colours

Peacocks, kingfishers and bluebirds are among some of the most eye-catching of birds, and in many cultures are particularly admired for their rich blue colours. We¬†have long known that red and orange birds take their colour from their food, extracting pigments in the plant and animal matter they consume. Flamingoes are possibly the best-known example,…