Combat-dance between WHAT?

[Lizrd_boy]

Can't they interbreed? I know there's some crazy hybrids out there in the trade already and iirc copperheads and cottonmouths are closely related. Granted, such hybrids are from enforced pairings that would normally never happen (for example ball and retic pythons) but inter-species pairings in the wild are nonetheless not unheard of.

They are in the same genus (Agkistrodon) so technically it is possible. I'm not sure if that's the case here, but it's possible.