Animal Rights is a side mission in Borderlands 2
Sanctuary (Mission Start)
Turn in: Mordecai
Mordecai wants revenge.
Rare Sniper Rifle (Blue): Trespasser
Go back to the Wildlife Exploitation Preserve and then to the Preserve Dockyard. Head to the southern docks and pull generator level to open the cages. Stalker Handlers arrive and they attempt to control the Stalkers. Kill the Stalker Handlers fast.
Proceed deeper into the preserve, same route you took during the quest Wildlife Preservation. Pull another lever to release Skags and kill the Skag Handlers. Go through Specimen Maintenance and onto the Observation Wing. Pull lever in Warehouse Office and set the Badass Stalker free. Kill the soldiers that arrive before they can kill the Badass Stalker. Use Fast Travel Station to head back to Mordecai in Sanctuary.
Strategy Guide - Tips - Cheats
Use Corrosive Weapons to cut through the armor of the handlers that come to kill them fastest before they can kill the creatures.
The faster you kill the handlers, the more creatures survive, and the more bonus cash you get as a reward.