Gwpercle.
They are most likely honey bees!
There are several strains that are stingless and someone near you may of had them at one time and they swarmed.
As to their entrance being close to the ground versus high in a tree it is just as normal close to the ground.
Ever see a bee hive? The entrance is usually only inches off the ground.
When they swarm they look for the best housing available and if the entrance is low or high they take it.
I would say enjoy them and hope they do not become africanized or as Chrisw says a" hot hive"
as then they become very agessive and no one is safe.
I belive Chrisw as I had several "hot Hives" as he says and wound up requeening them in hopes of calming them down. Didn't work so killed them off and replaced them with packages.
All bees "hot or otherwise can be handeled with the proper equipment " protective" but if they are in a residential area be very carefull as you are liable for their behaviour!!
chrisw , where are you located?
haven't been around bees since wife became sick and had to move.
Nice to talk to someone still in the business.
What is the going rate per hive for polination now?
beekeeper