While you may use weather trends to know when to get out your favorite winter sweaters or put away the water hose, some animals use the weather to tell them when it is time to migrate.
Arctic terns have the longest migration of any known animal. They travel more than 31,000 miles annually. Their fall migration from their Arctic summer breeding grounds to their Antarctic wintering grounds usually starts in September, with most arriving by November.
They linger where they can get good food and wait until there are east tailwinds to push them along.
While scientists are not sure, these 4-ounce birds may rely on changes in atmospheric pressure, cloud patterns and changes in the magnetic field caused by weather phenomena to know when it is time to migrate.