Pest control

No preferred power plant stated so...

Evanix AR6 pistol has enough power for sure! Wear earplugs or get a good LDC. A repeater pistol with a quick cocking like a revolver not a semi auto. Maybe if you bear with the heavy trigger kinda semi auto 6 shot I guess.

A cheap co2 Crosman Vigilante pistol would do for birds at close distance but not sure about chipmunks and squirrels though.

No price budget stated either so...

Steyr LP50 HP should do it for chipmunks and squirrels as well and is a true semiautomatic match grade pistol.

You Will definitely need to provide ear protection to your chipmunks and squirrels for this one as well!