So I found a nice embark location; I'm in war with both goblins and elves, there's forest and plenty of metal and everything is good. Hell, there was even a cave (fortunately empty) I discovered only after embarking.
There was some weird "Urist cancels to store item to stockpile: item inaccessible" -announcements multiple times. I walled off the cave entrance and they stopped.
There was also a giant mole wandering in the surface. I guess it had come from the cave. There was also some dead giant moles and trogodytes in the unit list.
Well, after I got military up at the second spring, I decided to send a exploration team down there. In unwalled the cave entrance and descended into the depths with my bismuth bronze -clad team of dwarves.
I found corpses. Troglodytes and giant moles. Some of them even were so fresh that dwarves started to bring them into butcher's. Most of them, however, were rotten.
I expected to meet an FB or cavern tribe which had killed those.
The expedition continued. I found a downward passage and descended yet more.
My dwarves killed one "giant mole pup". It was odd, since I have never seen children of wild animal before. There was also a giant mole, but it was quickly pulverized by hail of arrows. (I have started to give my spinners/web-guys crossbows).
I had charted both cavern layers. There was no passage to the third one. There was ~10 corpses total. I don't have a slightest idea what had happened, since there was nothing hostile in that cavern. Just giant moles and a couple of cave floaters.
Any ideas what the hell is going on in my caverns?