Science Questions

Is there a metabolic cost to the generation of bright colours in animals? Gary Stab

It’s a very good question and you‘re absolutely right and there are pigments that animals use to attract mates. That’s generally what it’s all about. These are molecules that are quite costly to create. Not to mention the fact that you also look more obvious to things like predators. This was a question that someone, a guy called Geoffrey Hill looked at. He’s from the University in Alabama. He looked at house finches that grow colourful feathers in yellows and orange and reds using carotenoid pigments. Similar to what Dave was talking about earlier. What he did was he actually fed a bunch of house finches with these types of pigments in water. He fed half of these birds lots of food so they were nice and happy and were doing great. The other half he restricted their diets, which wasn’t very nice. Basically he wanted to know what the difference was when they did and didn’t have enough food to eat. As you might imagine, the ones that didn’t get enough food were much more drab than the ones that had lots of food who grew lots of night, shiny colourful feathers. That’s a really good way of showing to us that yes, producing pigments is expensive in food and if you haven’t got enough food to do that then you tend to not be able to produce such brightly coloured feathers.

May 2008