Why are tropical animals so colourful?

FROM THE VIVID FEATHERS OF RAINBOW lorikeets to the bright blue bottoms of mandrills, the tropics are certainly a flamboyant feast for the eyes.

- Helen Pilcher

Writing in the 19th century, Charles Darwin was struck by this, remarking on the “rich variety of colours”.

This is borne out by modern research. A team led by the University of Sheffield studied more than 4,500 different songbird species from around the world, preserved in London’s Natural History Museum, and found that tropical songbirds are more colourful than their nontropical counterparts.