Vole – essential food
The fox's most important food is vole but here the male fox has caught a much larger prey, a grey hen. Why is that?
Cost-benefit
Every delivery of food costs energy. To carry home a vole is cheap, but its yield is small, because the vole is small. To change to larger preys, like black grouse, is more profitable: Cost is weighted against profit!
Do foxes think?
Can the fox calculate what's the best thing to do? Hardly! It behaves this way automatically, determined by its genes. No! Individuals who have behaved like this in past generations survived and propagated more than others. Their cubs inherited the behaviour. After several generations more and more individuals received this character. That is why foxes behave like this today.
