I have not done any work with chipmunks. I have a customer that called me with holes burrowed right up alongside the foundation of their home. They suspect mice or screws and have been baiting with mouse bait of multiple brands (which is being consumed) and setting a small cage trap. They have cought many chipmunks and released them down the street. Some of the holes have styrofoam insulation they are getting to behind the siding. The hole are 1 1/4"-1 1/2" diameter. That seem a little small for chipmunks to me but it seem logical to me that chipmunks are the culprit. I am planning on setting up a camera to confirm but wondered what any thoughts were. Thank you.

Voles maybe.

Meadow voles it appears. You can catch them with staked and properly set expanded pan mouse traps. Do some research in the achives. I posted some jobs a few years ago showing a set up etc. You will likely catch some shrews running in the vole runs and tunnels also.