Interesting bee gathering...

[Shizzell]

They seem to just pile up on top of each other there as the night goes on. They've done this now for 3-4 days.

I don't think its bearding. However, it rained 2 nights ago.

Any Clue?

Jake

[doak]

Not a bad cluster. Looks like the heat may be building up a little. How hot is it there?
Late in the evening the amount of bees returning to the hive and none leaving, you get a build up like that and they will not go inside untill it cools down. Check early morning and see if they  are still there.
That cluster will get bigger the hotter it gets.
doak

[likes2grill]

Looks like they're scrubbing the floor to me. I see it all the time in my hives. The more house bees you get the more there will be on the outside cleaning/scrubbing.

[Kirk-o]

Bees will be bee's you know
kirko