Few people have the tenacity of ecologists Peter and Rosemary Grant, willing to spend part of each year since 1973 in a tent on a tiny, barren volcanic island ... birds with deep, strong beaks ...

Then the smell hits, a choking reek of fish and ammonia from the birds' guano ... with vivid orange detailing on its head, beak, neck, and upper breast. On Possession Island king penguins have ...

The two-colour discs had different pairs of colours selected from an orange-to-red spectrum. This mirrors the colour range found in the male songbird beak. One idea was that the birds would be ...