Answer: Wish there were a quick answer to your question! Sometimes birds, especially crows, will excavate small holes, looking for grubs or other good things to eat. Or, the holes may have been caused by voles. Voles are small rodents, also called meadow mice or field mice. They do not hibernate, so they may be seen any time of the year. They construct surface runways as well as underground tunnels and eat a variety of plant material. Tunnel entrances are 1 to 1? inches in diameter and no mound of soil is present. If you think it might be voles, you can just ignore them - they will probably move on now that the snow is gone and food is easier to find - or you can set mousetraps in the tunnels.
Best wishes with your project!
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