In an effort to stop the yearly goblin raids on my shorter dwarves, I set up a host of traps near the entrance of my fortress. Normally this either stops all the goblins, or one or two gets away with a kid. This time, however...after receiving a message that one of the children had been kidnapped, I noticed that two of the goblins had tripped cage traps.
I was a little surprised when the next message I saw in regard to the kidnapped child wasn't about his death, but him throwing a tantrum. Checked his profile, and noted his complaints about confinement. Centering the cursor on his position showed him to be in the same square as one of the caged goblins...but not in the terrarium along with the goblin.
I then endeavored to get the goblin out of the cage, hoping that its death would free the kid. Setting the cage up as a piece of furniture and deselecting the goblin as an occupant didn't work; apparently the goblin was bright enough to realize coming out of his cage in a barracks full of armed dwarves wouldn't end well for him. Next attempt involved trying to drown the cage; again, no success. My final attempt actually got the goblin out of the cage; I reassigned it to a different one. However, the path my dwarf chose to lead it along was rather unsafe for the goblin, who failed to slip by a stonefall trap.
All this work was apparently for nothin', as the kid's still complaining about being confined...though I'm not sure I want him back, if he can't get away from a dead goblin thief.