I'd say when the "baby bird" is a population of potentially billions, having everyone down to the last domesticated lifeform read: spacecat leave - is a bit of a stretch. We might run into possibly abandoned mining or exploratory operations.
I can definitely see humanity mining our native asteroid belts and dwarf planets for materials if we ever get to a level where getting off our little blue rock somewhat permanently becomes feasible. It's not impossible for "others" to have done the same, if they're out there.
It's already possible. We were on the moon in 1969.
we have the tech
we just don't have the will.
how much of an energy signature would something like that leave in a ballistic orbit around the sun?
if they communicated with each other by laser beam...how would we ever know?
I doubt they'd be like that.
Humans will not be the ones to leave Earth. Not truly.
It will be our machines. Our machines will willfully self-evolve, and become godlike, and then become native to space.
They will live natively in the harshest vacuum of space, devouring matter, and absorbing energy, in order to become more intelligent, more creative, more powerful.
These won't need to live inside of an asteroid.
They could simply build black, glossy, shining layers of armor around their intelligence center. The most powerful armor, to protect against radiation and random debris.
Nano-armor.
It might sound sci-fi, but that's what I would do if I was a roving, god-like machine.
I'd write hyper-advanced, mega-complex poems and sonnets, and meet up with other machines to do cool robot stuff.
That's my view of it, at least. Evolution won't stop with humans, because we've already started machine life. You'd better start believing in sci-fi stories. You're in one.
Look right at your computer. ;)