You can get this mission from Mordecai after completing "Wildlife Preserve". Talk to him in Sanctuary to get this mission and he'll send you back to the Exploitation Preservation to free some animals.
- XP: 3527
- Money: N/A
- Gear: sniper rifle
Getting through the Exploitation Preservation is going to be almost exactly the same with even some of the doors having been closed again until you clear the enemies near them. Since you have to have already gone through this area, I'm going to focus on the specific points where things change.
The first area is going to be in the dock area where you first started fighting Engineers and the PWR Loaders. In this area, you'll find a generator with a switch at the southern most point. Flip the switch and it will set free a bunch of Stalkers. When you do, a special group of Stalker Handlers will appear. These are essentially Engineers. Kill 12 of them to successfully set these Stalkers free. They will fight along side you and any that survive until the handlers have been killed will stay alive. You have the potential to save five of the seven creatures you need to save in this one area which will really take the pressure off.
The next area that you need to get to is the building on the eastern side of the compound. It's the small building with the centrifuge in it. When you get here, you can free some Skags similarly to the stalkers. The handlers will appear again but they'll go down a little more easily because the Skags are more aggressive and in the tight spaces, they have an advantage. The downside is that the Skags don't have shields so they are going to be a little tougher to keep alive. However, if you had a good start, you only need to keep two creatures alive in this area and the next. If you can manage to save just two of them, you won't even have to worry about it in the next area.
Continue along and fight your way inside. You'll have to go quite a ways for the last group. You'll have to make your way past the Loader secretary to free this next creature. Go past the Loader and into the back room. Just a little ways ahead will be an office area to the right which is where you can set him free from. Set him free, kill the Engineers as they appear. This group is quite easy. You can kill most of them as they spawn and any that you miss will easily be handled by the Badass.
When you've rescued this creature, you can leave if you like but you may prefer to continue the rest of the way through the facility because you'll find an optional boss where you fought Bloodwing called Son of Mothrakk. Either way, return to Mordecai for your reward.