Recently, I had one of my lumberjacks (curiously) go into a fey mood for bones. However, having just used up all of it for crafts, I had four choices:
1. Grave-robbing from my tombs.
2. Kill wildlife, which would interrupt/damage my plans for an eventual wildlife preserve to counter extinction.
3. Kill my current trophies-in-waiting, two caged wild elephants.
4. Drop a stone cieling on the elven traders and harvest from their donkeys.
After the first option failed, the choice was pretty clear.
How many more times can I do this before war starts?
As far as I know, elves will never war with you. At least I have never gotten them to, and I have slaughtered elves by the dozens. Eventually they just stopped coming.
Destroy all the trees in the area, and place the logs around the trade depot, all the while, you trap them in there, as you unload a ton of water to blast them into an arena, with animals being viciously slaughtered, as they are helpless to save them because they can't shoot through windows.
That plan will hit all the anger points of the said
"oriental" "DRUIDIC" entities, and if you want them to war with you, let them leave after the animals die, and use a water cannon to free them.