Why on the world you look info the hive in winter? You disturb them, that's why they died. If they don't have enough food, you didn't feed them properly in autumn.
In an ideal world the autumn feed will be enough however nothing in beekeeping is ever that simple and if colonies are light in January, feed fondant. Otherwise you will not have any bees in the spring, which is rather counter productive.
Why on the world you look info the hive in winter? You disturb them, that's why they died. If they don't have enough food, you didn't feed them properly in autumn.
In an ideal world the autumn feed will be enough however nothing in beekeeping is ever that simple and if colonies are light in January, feed fondant. Otherwise you will not have any bees in the spring, which is rather counter productive.