Well; if they don't migrate then how did these Grey Squirrels get here ? 30 years ago we only had Fox Squirrels along the creek where I hunt.
What you have experienced is dispersal, not migration. When an area becomes too crowded the young of the year, in particular, will usually seek out fresh turf. That's dispersal. Migration is a seasonal movement between two territories. Usually north and south, or up and down in the mountains during Spring and fall.
Keep both eyes open and make the first shot good.
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