Hey i just got 2 acres and its just full of large blacksnakes i think they ate all my frogs !
Black snakes here are rat snakes and they are very long with a white bottom.
The frogs and salamanders will die off faster than many other critters from pollution or other environmental stresses. Hopefully it is just a transitory stress and your froggies rebound in a couple of years.
What is the usage history of your 2 acres - was it farmed or logged?