After weeks of being stuck at 94 animals killed out of 100, I finally managed to get the buckle after brainstorming what I was missing. Chipmunks and snapping turtles slipped under my radar, the crab I had to go out of my way for, and I finished it by hunting for a panther at night with a poison arrow which was really neat. I got it to spawn surprisingly quickly south of Rhodes. I was so lucky to see a moose already at Owanjilla, I haven't even seen one in story mode yet. I felt bad killing it at the time but I'm sure glad I did in hindsight lol.