Wild animals digging in the yard
In the last week or so there has been a great deal of hole digging in our back yard, which backs up to Maryland State Park so it's pretty wild. We have had this before, usually in the late summer or early fall, and it was suggested that at that time of year the culprits are skunks. There has never been so much damage in the late winter. Last year I put down milky spore in the summer, and castor oil-based mole and vole deterrent, because those are the critters that I believe are drawing the diggers (and are being drawn by the grubs). But . . . I really don't know, nor do I know the best course of action at this time of year. The damage is significant, especially because they are digging up small shore juniper plants that we installed last fall to start replacing lawn with ground covers. The diggers leave the poor little junipers lying exposed next to their holes. Help!
Grubs are very deep in the soil this time of year (to cold!), so digging for them seems unlikely. That is very common in fall.
Unless you have a huge number of grubs, (about 10 per square foot) we wouldn't recommend grub control measures, especially not for wildlife problems because of the expense and lack of solution. (Actually, we stopped recommending milky spore years ago because the spore populations had become less effective and it is expensive.) Grub control also doesn't prevent moles and voles.
It may be that predators are targeting moles or voles. You don't mention whether you have those. Here is help with both: https://extension.umd.edu/hgic/topics/voles
It's also possible that squirrels are simply digging up the acorns and nuts they buried.
One way to counter digging is to lay sheets of chicken wire or hardware cloth over beds or problem areas. Pin it down. Plants can grow through and wildlife can't dig there.