Join Date: Sep 2017
Location: Apple Valley, CA
That snake would absolutely be able to swallow a pinky mouse.
The challenge with wild caught reptiles is stress. If you want to keep it long term/turn it into a pet, I'd suggest getting a minimum of a 20 gallon long for it. Provide it with plenty of cover and a large enough water bowl for swimming. Have a warm and cool end, with a hot spot of around 90-100 degrees surface temperature. IR guns are perfect for taking temperatures.
Set it up like this and don't handle the snake unless absolutely necessary, let the creature de-stress for a couple of weeks. Fish and frogs are favorite prey items of the garter snake. Once it starts eating, a great way to transition the snake onto rodents is to "scent" the prey items by taking a frog/fish/whatever it is eating at the time and rub it all over the rodent you want it to eat. That will trick the snake, in a way, into going after the rodent as food. And as time goes on, it will get used to the taste of rodents and you won't have to scent them any longer. I had to do this once with a false water cobra, it's actually quite easy.
Reptiles have their own tricks to them - but much like fish, stress is probably the #1 killer. However, unlike fish, even under optimal conditions, a stressed reptile can go quite some time before it starts accepting food.