A hunter named Odie Ellis has written to Field & Stream suggesting the government should put Bigfoot on the Endangered Species List, in part to keep hunters who think they see a manlike form from nailing another hunter. The idea is attracting a lot of comment from cryptozoologists.
Over 30 years ago, the Colorado Springs Gazette-Telegraph published an article saying Bigfoot has been put on the Endangered Species List. When I wrote to the USFWS, a staffer wrote back (I still have the letter somewhere) that this “imaginary creature” had never been considered for protection. He added that, if the animal were proven to exist, it might be considered as a candidate for listing. I still don’t know how the article originated. No one I talked to at the paper had any idea.
There’s no reason to think the USFWS implementation of the ESA has changed. Absent an amendment to the law by Congress allowing reported species to be added (not going to happen), Bigfoot is not going on the list until there’s a bigfoot type specimen in hand. (Speculation: IF there is a type specimen available for scientific examination, protection might not wait until the formal species description is published: the Secretary of the Interior has emergency powers that, in a case as remarkable as this, might be used to protect the area the type specimen came from.)
Anyway, if Bigfoot exists, he's on his own as far as the government is concerned.