Since the death of BLB we made a few adjustments to the nest environment for Holly, who survives him.
One of the key things was to start putting honey-water inside the nestbox as she rarely seemed to be coming out to drink. In fact she seemed to have reverted to "nesting behaviour" - i.e. staying inside the nestbox, guarding it, fixing it and patrolling it whenever there was a disruption. We started to think she had adopted this as a "role" and was thus destined not to come out of the box. Therefore, just as in a real nest, we would have to provide supplies for her inside the nest.
This worked well - we provided a few droplets of honey water each day and they would be disappearing and we could hear her being active. We couldn't see her much when the lid was on the box because she spent a lot of time in an area of bad video coverage and also under the moss - but we could hear her scratching around.
However, as time went by I was a little concerned that she was becoming more dormant - spending most of the time resting (sleeping?) under the most and not doing anything. If we disrupted her nest she would come to the entrance, perhaps outside by a few centimetres for about 15 seconds - but basically was more or less "hibernating" under her favourite patch of moss in the nest.
We thought maybe some extra heat would encourage activity as it seemed to have a postive effect when she and BLB were in the smaller icecream tub. So, we discarded the normal wooden lid of the nest box and built a cardboard one with a hole in it. Over this hole I mounted the infra red light I had bought to boost the night vision in the garden (but never yet used). This light packs some serious punch - designed to light a 20 metre square area.
The light is doing a wonderful job of heating the box - underneath it is getting to about 30 degrees - at the far end about 25 degrees. This is perfect for Holly as bumblebees keep their nest at 30 degrees. And we can tell she loves it. First of all she spends most of her time under the light, every once in a while doing the "bum fandango" (as BCW calls it) and twirling round on the spot.
We also decided to add pollen to the box. Although this is used to feed larvae in the nest (a source of protein), there is a role for the nest-dwelling bees to make this happen, and they make "pollen bread" for this purpose by mixing pollen and honey. We haven't been disappointed - Holly has shown great interest in the pollen (even though she didn't when it was in the original ice cream tub). We can't quite tell what she's doing with it, but on occasions it looks like she is pushing little pollen balls around and possible making them or breaking them up. Tonight we saw her standing in the pollen, drinking honey-water, then heading into the pollen to scratch around.
She also spends a lot of time scratching at the floor (as shown in the videos). We don't really know what this behaviour is - it seems really pointless, but then I wondered if this is what she would be doing if she was helping new bees to be born - trying to scratch/break them out of the waxy pots.
The thing is, we are using "bee logic" to figure out what to do and to make sense of what we see. We make the assumption that Holly will behave most naturally as if she is in a nest if she believes she is really in a colonised nest. And so making her environment as nest-like as possible means getting the temperature right, the contents right, the food source right and so on. I truly think we are now managing to get those parameters as close as we can realistically expect to (in a nest that is inhabited by one bee). Consequently she is carrying out the type of behaviours she would do in a real nest, even though she doesn't realise how fruitless they are.
What I'd love to do is add some "robot" bees to the nest, to see how she interacts with them :-)