Why do birds fly in formation?

Why is Pluto not considered a planet anymore? What is the possibility of there being more than one universe? Why do birds not get electrocuted when they stand on electrical wires? Is the universe finite or infinite? If it is finite, what is it expanding into? What is the actual measurement of a lightyear? How do meteors form? Why do birds fly in formation? Like this podcast? Please help us by supporting the Naked Scientists