That huge lump on the base of this Mute Swan’s beak is called a basal knob. Knowing that, however, tells you nothing about its function. What exactly is it for?
There are many species which have them. Often they’re larger in the males and they often change colour during the breeding season. It may be they’re caused by sexual selection by females looking for the healthiest mates for their family to be. But why there? And why like that?
Many people think that science has the answers to most questions about the natural world that we can ask, yet there’s still so much of life we don’t understand. Perhaps we should study nature and find out, before we’ve made many of the world’s species extinct?