I am lucky enough to have two bumblebee nests at the house. One is in the Gable end of the garage and the other in in an air brick in the house. The nests are about fourty feet apart and seem to be the home of garden bumble. ( smallish, thin yellow band, white tail).
I have spent ages watching them and was suprised when I noticed that some bees were exiting one nest and flying directly to the other and entering. This is happening in both directions and almost continuously .
If another insect, including other types of bumbles, come close to the entrance they are soon seen off the premises by the small swarm buzzing around the entrance to either of the nests.
Are these bees sharing nests in some way? Are the two nests part of one community ? Is this a commonly observed behaviour . Would love to hear from anyone on this!
First, welcome to the Forum !
Secondly, I suspect that you might have two colonies of Tree Bumblebees., which quite commonly nest in house eaves, soffit boxes, bird boxes etc.
The fur colour combination you report doesn’t fit with Garden Bumblebees (Bombus hortorum).
So, I suggest that you take a look at the Forum Threads about the Tree Bumblebee, Bombus hypnorum.
The male bees (drones) of this species do something called “Nest Surveillance” where they “dance in the air” outside a nest, hoping to mate with a virgin queen from that nest. The cloud of bees hangs around for hour after hour and day after day, but if you watch, you should see bees moving into the throng and others moving away from it: so there must be a “dwell-time” for each bee. I think these male bees have a patrol route, whereby they move around from nest to nest in your locality.
I’ve had colonies of this species nesting in bird boxes over several years now, so my knowledge from observations like you are doing has slowly built up. And I suspect that you are seeing bees transfer from cloud to cloud as they move from your nest 1 to nest 2.
You get some local “air movement” traffic going into / out of the nest, but most of the bees don’t go into the nest.
Do let us know if your on-site facts fit with my theory !