Question: If animals have no threat will their camouflage and warning signs go away?

Kevin Arbuckle answered on 18 Mar 2014:

Very interesting question – so interesting in fact that I might have to add that to the list of research projects I want to do! And from that you will probably guess that we don’t know yet.

However, there is some evidence to suggest that it might just be the case. Rattlesnakes use their rattles as a warning sign, and in a couple of cases there are rattlesnake species that live on small islands (or other areas without many or any predators) that have almost lost their rattle. It’s now so small that it doesn’t really work anymore, certainly not very well. Also, people have measured the escape response of some lizards (e.g. how close they let a ‘predator’/human get before they run away) and found that those living on islands (again, with few predators) don’t run away as quickly.

So it seems likely that defensive traits and abilities are lost to some extent in the absence of a high predation risk, but noone has really looked at this properly in camouflage as far as I know (or even warning signals, although the rattlesnake example suggests this). Some recent work I’ve done suggests that some defences are very rarely lost once they have evolved, but it would be interesting to look at this in more detail.