Instructions
Click on the "Puerto Rico" tab on the Mission screen to head to that island. Speak to the farmer there and get the fur from the fence to bring back to Mews as evidence of the Sasquatch. Head to the right to get the bolt cutters to use in New Jersey to help complete the Jersey Devil quest.
Return to Puerto Rico after discovering evidence of the Jersey Devil and Sasquatch. Ask to borrow the farmer's jeep, then use the jeep to herd three spotted goats into the center area at Snaggletooth Rock. A prompt will appear when the goats have been successfully herded.
Exit the truck, then meet the herder by the bushes at Snaggletooth Rock. The trap will snap. Go back to the truck to attempt to push the crate onto the back of the jeep. The crate will break open and the Chupacabra will howl at you, and run away. However, one of his teeth will break off, giving you the evidence you need to give to Mews.