Or a paintball gun.
Seen a post today about using a paintball gun, and it made me think about a seldom used technique by MABRC researchers that don't have thermals can use while researching.
If you think you have a Bigfoot standing in the underbrush, but don't want to approach it. Take a BB gun and simply shoot into the shadow where you think it is standing. If it moves, then you know it was a Bigfoot, if it doesn't, then it wasn't nothing more than a shadow. A paintball gun has the same effect. The Bigfoot more than likely will only react to it like a bug bite, but will move.
Many will claim that this will infuriate the Bigfoot and make it attack, I have used this technique before, and I still have all my arms and legs. I have seen two shadows move after being hit with the BB gun.