Small groups of bees under guttering

[john9159]

A bit off topic I know but I have noticed small groups of bees (not wasps) congregating in various locations at six houses within a distance of 200 metres.
The groups comprise about 12 bees and most are under the guttering of houses whilst mine are flying around a bird nesting box 12" under the guttering.
They do not enter the box, nor do they fly in and out of roof spaces above guttering but are presnet from dawn until dusk.
I have noticed one travelling between the various sites.
What are they doing?

[ploshkin]

A guess would be tree bumbles, they particularly like nest boxes that haven't been cleaned out. The ones flying outside would be drones hoping for virgin queens to come out on mating flights. Tree bumbles arrived in the UK several years ago and have become very widespread.