The purpose of the winter to spring inspection is to quickly determine if all is well. The hives should not be opened for long, since the cooling down of brood can lead to stress and subsequently to disease. Also there is a risk that the queen may be balled and die (Link needed for balling queen).
Hence the main two signs to note are:
- Is there enough food in the colony to survive the coming weeks?
If not, provide food in form of a small portion of warm sugar candy placed over the bees to conserve their heat.
- Is there worker brood in the center of the frames?
If there is, the queen is present and the colony will develop well. If not, then the colony is in trouble and it is best find to another colony to combine it with; preferably a weak colony.