Either I personally or people I know have crawled over every inch of that particular reservation. There's no bigfoot.
I don't know "where" this reservation you speak of is but the "Bigfoot" I am aware of in BC,WA and ORE is supposedly wandering around in several million square miles much of which has never been walked or crawled on by any human being. AKA "wilderness".
I used to climb mountains in the NW Cascade range and I assure you that if you have ever stood on the top of a tall mountain in Washington State your perspective of the enormity of the remaining virgin forest in this area is staggering.