Hostile because it was never my fault.

[Positronium]

A bunch of visitors from a faction (Sadly my relations with them were pretty low: 6) suddenly a man hunter cougar preys on one of the visitors, get mauled and now the many other cougars in the region are now mad, needless to say that faction was not very happy about it.

TL;DR Faction relations go down despite the problem not being caused by you.

[Canute]

Anything that happen on your map, belong to you.
It is your vault that you didn't hunt all the possible predators before, now you need to life with the consequence.

[SpaceDorf]

Yup.

But you can buy back goodwill by realesing prisoners or sending silver to them with the Comms Array.

If you want to ..