You need to kill the following animals, domesticated animals do not count for the trophy, neither do bats.
* Bears: You can find these in the Tall Trees area in the North.
* Beavers: These are in the Tall Trees area in the North.
* Bighorn: You can find this in the mountains in the Frontier and Mexico, and in abundance in the Tall Trees area of the North.
* Boars: You can find these in Pike's Basin and the Tall Trees area.
* Bobcats: You can find these in Mexico and the Tall Trees area.
* Buffalo: As you first enter the Great Plains from Thieves' Landing.
* Cougars: In the mountains and hills on the Frontier and Mexico.
* Coyote: On the Frontier and Mexico, listen for their whiny howls.
* Crows: All three areas, listen for their caws.
* Deer: All three areas
* Ducks: On the Great Plains near the edges where the water meets the land.
* Eagles: Tall Trees and Nikoti Rock areas of the North.
* Elk: Tall Trees area.
* Foxes: Near Riley's Charge on the Frontier and in the Tall Trees area in the North.
* Hawks: The Frontier and Mexico.
* Wild Horses: Any horse roaming any map that does not have a saddle on its back.
* Owls: All three maps, only at night.
* Rabbits: All three maps.
* Raccoons: All three maps.
* Seagulls: Blackwater near the water.
* Skunks: Around MacFarlane Ranch on the Frontier.
* Snakes: All three maps, listen for snake hissing or rattling while you are riding then check around on the ground.
* Songbirds: Near the towns on all three maps.
* Vultures: All three maps, usually near death.
* Wolves: All three maps, but in abundance in Mexico and the Tall Trees area.
I'm sure there are people who posted this, but I'm putting it in my blog and just stating for the record that the pictures of the animals on the map in the game suck. Looks like a goddamn ink blot test. You can make out some of the pics and tell what they are, but others just look like smudges.