Maybe the cats just peed! lol, how about hedgehogs digging for slugs or birds scratching for worms, grubs, grit,
I hope it's not rats, for your sake.

Could it be a badger? or perhaps a squirrel?

Over here the squirrels dig holes. They may not be the only ones.

Rabbits do that in my garden, do you have those?

What were the actual plants?

Also foxes. They eat lots of worms. can also be a problem if you use fish, blood and bone when planting. Perhaps a very dilute use of Jeyes Fluid, crushed moth balls or Obas Oil on old tea bags around the area might deter.

Are we talking about newly-planted plants, or well-established ones? And what sort of plants are they? Flowers? Shrubs? Unless we have those details, no-one can really know.

That's why I asked what the plants were Rosierose... we're in the dark right now!

We certainly are, MG! Perhaps the Op will get back with some info later on. :)