Personally, I think there's no point to them. I've never found them to make way to a safe path of anywhere (I commonly find them around things that are entirely NOT safe, including raiders and giant ants) and they're just here because they make the game better. And also,
Ooh, a settlement or merchants are over that ridge, look at all the people!
Dag nabbit, it's just birds.
Punishment. Wha-Bam.