Spring migration came to my yard today in the form of a male Red-winged Blackbird. He arrived well before what is their average return date in my yard (March 22), and might raise the question, "will we see an earlier spring migration because of our mild winter?"
As we emerge from our warmer-than-normal winter (though 18" of new snow now covers the landscape), we might be tempted to attribute earlier than normal spring arrivals to the mild winter. But remember that migration for many species starts thousands and thousands of miles from here and that a warm, snowless winter in the Capitol region of New York doesn't mean that birds will wrap up their winter stay in Mexico or South America or the Caribbean and start their journey north early.
There might be more of a chance of a single mild winter affecting migration amongst short-distance migrants, like Red-winged Blackbirds, some of whom spend winter in southern portions of the state.
But don't necessarily expect to see all your spring birds earlier than normal just because of a mild winter. If they do start arriving earlier on a continuing basis, it's something much bigger than a single snow-less winter!