Basically you need to shoot four different animals consecutively. i.e. duck, deer, zebra, buffalo (The description is not clear if it has to only one, but that's the way I did it)
I did this on the First Blood gallery.
After the first gate progress until you've shot the first three hyena (it comes up quickly). From there you'll have a nice mix of alternating animals. Be sure to shot ONLY ONE of each type. (If some can confirm they shot multiple types and got the achievement I'll edit this)
In order they will be: (be sure to skip the duplicates)
*Hyena (shoot only one-let the other two bite you)
*Ducks (shoot only one-easiest to hit the last one, aim low)
Buffalo -standing around (skip)
If you did it correctly the achievement will pop, if not you'll hit the gate and be bounced back to a checkpoint where you can try again.
I'm sure there are other places to do this, but this is how I did it. If you find an easier please let me know and I'll adjust this solution