Hi Lisa,

Based on the photo I'd say that the most likely hole digger is a chipmunk, because there is no dirt around the hole. Moles, groundhogs, and many of the hole digging insects leave distinctive debris traces, or mounds of soil.  Of course the only way to be absolutely sure if it is a chipmunk is to see one going in, or out.  Chipmunk holes are of most concern when they are near the foundation of a building, walkway, or wall, and could cause damage to the structure, or in the case of a house foundation create a channel for water to enter. Otherwise they are mainly a nuisance, and aesthetic problem. 

In my own yard I pour red pepper flakes, or ground cayenne pepper down chipmunk holes in my flower beds, or near my house foundation to deter the rodents from taking up residence.  I then fill the opening with soil, and tamp it down, and sprinkle a little more pepper around the top. Sometimes I have to repeat the process a couple times before the chipmunks move to a place I find acceptable.  There are also commercial formulas for deterring rodents, including chipmunks, these are either based on predator urine, or some kind of strong smelling substance.

I've provided some links to resources on identifying hole diggers, and deterring them so you can both confirm the culprit, and work out a plan for deterrence that will work best for you.

https://rocklandcce.org/resources/chipmunks

https://bpb-us-w2.wpmucdn.com/u.osu.edu/dist/0/90535/files/2023/12/Moles-Voles-and-other-Holes-OTF-Short-Course-Dec.-2023.pdf

https://naturalresources.extension.iastate.edu/wildlife/diagnosing-holes-yard

Kind Regards,