Check out my coop ❤️

[bigz1983]

You could put a bird bath deicer or bucket heater/deicer in the barrel to stop it from freezing.

 

[aart]

They sell heating rock/pad things I plan to place one under the base of my drum

That's a lot of water to heat...for, what, a dozen birds?
Heating from outside the barrel won't be very efficient, may not even work.
Does the lid come off that barrel?
Could drop a trough heater in there and insulate the barrel.
Or look at something smaller for winter.
You've got all summer to think about it.