system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Why do birds waste their time migrating back north in the spring/summer? Wouldn’t it be easier to just chill down south year round?
gpt
Birds migrate north for the summer because there’s untapped resources and less competition up there.

Down south you have competition from all the non-migratory species and threats from all the local predators.

Rather than deal with that while trying to raise that year’s chicks, they fly to a place where there’s fewer local competitors and predators due to the harsh winters.