Thnks for the info guys. Blackwell Bikes, your experience using airguns with similar power is helpfull.
In the past I've used .17HMR, .17 M2, .22 mag, and I will continue to do so. BUT, there is this one spot, right behind a barn, against a fence under trees overlooking a pasture with a creek behind it ( hence, limiting range ), that I think it would be fun to use the Super Colibri's. And, the non-existant noise should keep them popping up.
Mark