I finally found a way to save my fort from that gorramed bug. It's not entirely the keas' fault, but rather, that damned
≡minecart's≡. It's a freaking holy grail of sorts that can destroy the world if ever destroyed by any means (And I mean
ANY means; Can't be stolen, burned, or lost in any other way. Not even deleted. But It's safe if buried under water; so it must remain intact for all eternity, lest my world ends). Even outright deletion via DFHack (Yes, I used Autodump's delete option to get rid of it, and it gave me the same exact bug. I can't destroy it by any means, even incinerating it in the magma pipe after the keas left with my wheelbarrow fleet instead).
What I must do instead is to build a shrine of sorts, or a vault in which it may never be touched, and keep it buried to never be found, along with any other artifact item that if anything happens to them, then my game's world will end. But in the meantime, I will keep it autodumped in a murky pool, where the keas and kobolds won't be able to reach it. I must build a dwarven jawbreaker vault. It's a hollow obisidan container 3x3x3 (center-most point is empty) in dimensions, buried under a layer of water and a layer of magma; next best thing is to bury it in Hell itself.
For what it's worth, at least I salvaged my fort, and can finally continue it without another crash for now.
EDIT:
Nevermind. I just found an alternative bypass method. Apparently it does somewhat have something to do with those damned keas. Apparently the main target of the lead kea is what is the accursed item. Because I destroyed the problem ≡minecart≡ before the flock appared, and my game is safe. I gotta do more research on these destructive birds.
EDIT EDIT:
Oh wait, Nevermind the above. That ≡minecart≡ is still the eye of the beholder for the keas. They just arrived, and the game crashed. I assume that was still their primary target. Well,
Project: Black-Box is still a go. That minecart, along with any other world-ending non-artifact artifact is sealed forevermore.
I can imagine the Biblical texts and archeological/adventurers' thoughts about this: "An ominous black box etched with nothing but warnings all over it in every conceivable language is known to contain an artifact that will end the world if ever touched. (A true Pandora's Box/Pandorica)" "What be this dangerous item of fable sealed within?" "A minecart." "A Minecart, Urist?" "...Yeah. A minecart. I don't understand either. What's so evil about a minecart? And a wooden one, while at it, that it had to be sealed inside such an artifact?"
BRILLIANT! I'm not sure, but there has to be some sort of way to foresee these kinds of bizarre errors. Or a DFHack plugin that allows you to foresee what the next item on the hit-list is (be it child or valuable item).
EDIT EDIT EDIT:
Project: Black-Box is completed. It looks beautiful and ominous. Forgive my cheating to summon an obsidian monolith like that, but I did what was necessary to forever preserve the sacred game-crashing relics (I seal them by using the DFHack Autodump function to plop them inside the impassible obsidian monolith).
The engraved box, showing warnings not to open it.
And the land in which we're doing it all in. I was too impatient to make a magma-cast of one. DFLiquids was necessary given the short notice. (Click image for larger screenshot)
Oh yeah, and due to the interesting nature of the liquids plugin, I smoothed and engraved all blocks of the monolith; even the seemingly unreachably impossible. It's to further ensure it's ominous nature. On the plus side, crisis is finally averted, and I can now finally continue on with my fortress.
EDIT EDIT EDIT EDIT:
Once somebody comes up with a way to teleport creatures and dwarves, this can also serve as a Pandorica to seal dwarves that I really, REALLY don't want involved with my fortress's macro- and micro-managment.