Pictures. ******-off insects defending nest are not a way to measure how docile they are. Multiple species of bumblers and yellow exist in a given area.
I keep honey bees as well and I am also familiar with the natives including some of the bumble bees. You can allow their persistence close to birds, just make it so birds do not get directly into nest.
All sounds typical of bumble bees but I do not know of any "ground bees" that are social and inclined to attack. Where I am at bumble bees are in trouble so I does as little harm to them as I can. It you make it so the birds can not actually get to colony entrance then bees should not attack...