Blueberries have shallow roots that can be sensitive to winter conditions and mulch will counteract this by moderating extremes in soil temperature and moisture levels.
Acidic mulches such as bark, peat moss, sawdust and pine needles will conserve moisture and maintain proper soil pH. Manure is commonly available but not recommended because it is not as acidic and may change the soil pH to an undesirable level.
Keep your plants protected from rabbits. Use a wire barrier, like chicken wire, and calculate the height of the wire based on the anticipated increase in snow buildup. This will ensure the plant is protected even under an accumulation of snow.
In coastal gardens apply mulch and ensure the soil is free draining. You will benefit from these few steps by enjoying a plentiful harvest of berries every year.