Why kill it - even if it is poisonous?
Where I grew up, we had a lot of copperheads. Even the little ones would curl up and prepare to strike rather than run away. We came across more than a few curled up in the middle of a cow trail daring someone to get too close. Between fire ants, cow manure, and snakes, you learned to always watch where you put your feet. They liked to also hang out on the concrete steps at the doorway in the evening after the sun goes down. At least one time we saw a copperhead curled up on a bush about 3 feet in the air.
There were lots of non poisonous snakes out there that hid and kept to themselves. We often would not even see them.
Outside dogs would help spot the snakes and at least bark at them.
Predator birds are more numerous now than when I was a kid. That might help also.
