That's the way I used to do it until I saw these heaters. It is just light heat and I'm not sure they would work in an Arctic blast, but so far, so good.
Thanks for the welcome. We have cold winters here, sometimes. I am not sure how Anna's survive when everything is frozen and all flowers are dead. I think they depend on feeders.
I've had Anna's hummingbirds in my yard all winter. I have a heated feeder for them. Rufous hummers will be here soon, too. Late Feb/early March. Everyone loves watching them.