Why are toucans so brightly colored?

Why the bill is so large and brightly colored is still debated and may be complex. As there is no sexual dimorphism in coloration it is unlikely to be a sexual signal; it does aid in their feeding behavior (as they sit in one spot and reach for all fruit in range, thereby reducing energy expenditure). It has also been theorised that the bill may intimidate smaller birds, so that the toucan may plunder nests undisturbed (see Behaviour). Also, the beak allows the bird to reach deep into treeholes to access food unavailable to other birds, and also to depredate suspended nests built by smaller birds.