If there were no birds, there would be an overpopulation of insects and mountain goats.

Then insects would have their own insect white house and declare war on the mountain goats as they expanded towards the mountainous regions because of gross overpopulation, and with the advent of personal hygience in the insect community, their population exponentially increased to the point where the expansionist dictator of the United Insects of America find that the only places to expand to are the mountains

And so began the Greatest War of All Time — Insect War I, followed by the sequel Insect War II which was against the Earth’s atmosphere because the insects began to develop in such a way that they could fly through space if they only breeched through the atmosphere.