I have had a hunch that the bees are at the end of their winter stores of honey for that last week or two. The late summer was not good for nectar, and while they took in a significant amount of sugar syrup and dry sugar in the fall, I was not confident that the bees had enough to get them through winter. I prepared myself for the first high 30s to 40 degree day by slicing some fondant and sandwiching them between two pieces of waxed paper and waited. Today's temperature is around 38 degrees, so I decided to feed the bees quickly.
The first hive I worked with is Nuc To Be Named Later. I took both the telescoping cover and the quilt box off, and sure enough I saw a good two dozen bees festooning out of the opening of the inner cover. Yes, they were in the top box and probably had little honey left. I placed a fondant "sandwich" near the bees at the opening and closed up quickly. In all, the operation took no more than two minutes. I went on and finished the other langstroths the same way. There were only a few honeybees at the top of Lib-BEE=taria (which contains carniolans) which I suspect have been a little more thrifty than the Italians in Nuc To Be Name Later. However, in Bee Glad..., the bees were in the same state as Nuc...,gathering about the opening in the inner cover. Like Nuc..., Bee Glad... is inhabited by Italians.
I also fed the two top bar hives. I opened up one of the secondary entrances in both hives and inserted a "tube" of fondant surrounded by sliced wax paper.
The whole operation took me little time and produced little stress on the bees.