On your first trip to Puerto Rico, you get some fur that turns out to be a wild dog's fur.
On your second visit, the herder comes up with a plan to trap it at Snaggletooth Rock (center star). You have to use the Jeep to herd 3 spotted goats into the spot in front of the cave. You get out and you'll meet the herder there. He has already set a trap and you wait behind the rocks. You will catch the chupacabra in this large crate.
Things don't work out as planned, but you do get proof of the chupacabra to take to Mews.
Not really
Yes, you can find proof of The Jersey Devil, Bigfoot, Nessie, and the Chupacabra. (see related question)
You can't. But its tooth is proof enough that it is an unknown species.
Take it back to Mews. Once you have gotten the photo of the Yeti footprint, and proved the other three cryptids (Nessie, chupacabra, and the Jersey Devil), Mews will send you to track down Bigfoot.
You have to look for Bigfoot/Yeti in the Himalayas, the Jersey Devil in New Jersey, the Loch Ness Monster in the Loch Ness in Scotland and the Chupacabra in Puerto Rico.
You need a photo of Nessie at Loch Ness, a tooth from the Chupacabra from Puerto Rico, and egg shells from the nest of the Jersey Devil in New Jersey. (see related solution)
When you first start the island and you get the paper about Mews needing the evidence of ONE cryptid to get your reward, you end up needing to search for 4: Bigfoot, the Loch Ness Monster, the Chupacabra, and the Jersey Devil.
you have to have three goats and.. that farmer dude to help you
After you have confirmed the other three cryptids (Nessie, Chupacabra, and the Jersey Devil), and brought back the inconclusive footprint from the Himalayas, Mews will send you in pursuit of Bigfoot, which is similar to the Yeti.
There are 3 you have to prove: Nessie (Loch Ness) Chupacabra (Puerto Rico) New Jersey Devil (New Jersey) You can't get what you need to prove the Yeti, so you are sent to find Bigfoot.
You need a photo of the actual Nessie, a tooth from the chupacabra, and egg shells from the Jersey Devil. (see the related questions below)
You get the fur from a fence in Puerto Rico. Back at the lab, you run a DNA test, but it turns out to be ordinary coyote fur.