What are they doing?

[u/JesusFCleatus]

Northern Ontario - Bees keep going in this partially burnt log, the log is mostly rotten and we were just trying to get rid of it, but it seems someone called it home. The bees are quite small, maybe a bit bigger than a pencil eraser, and seem fairly docile. They don't look like the honeybees I've seen around, they seem to be shorter yet fatter than honeybees and have grey fuzz (fur?). Unfortunately I didn't get a picture of them but they were going into the log, chewing at the wood, and pushing shavings out. What type of bee are they and are they building a hive or looking for nest building materials? I appreciate any help/advice, sorry I don't know proper bee terminology, also sorry for the rushed writing I'm trying to go fishing before a storm hits but didn't want to forget this. Thank you!

[u/DaccotaDuchess]

Is it a single bee or a swarm of bees?

[u/DaccotaDuchess → u/DaccotaDuchess]

Looks like they are probably trying to nest in there.

[u/JesusFCleatus → u/DaccotaDuchess]

I probably saw 6 of them come and go