What you're not seeing is that the Elk and Mulies there are non-native and are eating some rare plants that exist no where else. To people like Fienstien the order of things is:
1. Green Things
2. Furry Things
3. Human Things

Hence, she is willing to kill the elk on the island to save the plants, but she would also be willing to kill (or at least remove) the humans to save the elk (if they weren't killing the plants that is).

Sounds like a great trip and if you don't go before 2011, you'll never get the chance.

Good luck.