Why do birds fly south for the winter?

So my adorable, sweet, smart son and I were reading books tonight (note: he is soooo sick…he hasn’t eaten more than a 1/2 a pancake in three days – tomorrow is the doctor if no improvement). One of the books was Clifford’s First Autumn.

I asked him, “Andrew, what is another word for Autumn?” Andrew answers, “Fall”.

Then we are reading about the birds flying south for the winter. “Andrew – why do the birds fly south for the winter?” Andrew answers, “because they can’t walk.” He has his mother’s quick wit.