Probably the easiest way to search them is forestry sites on google. Most of them are seasonal jobs. I guess they know when there are more chances of forest fire. From what I have heard they don't pay a whole lot unless it's a long term contract. That way you do other work for them when you don't fly. Majority of them require lots of flight time because of liability/insurance issues I guess. I looked into those cause I wanted to fly the Martin Mars Flying Boat in Canada, but didn't seem lile the right way for me to go.