As an Austrian, I will not stand idly by when our cultural heritage is getting defamed like that 😉
https://en.wikipedia.org/wiki/1985_diethylene_glycol_wine_scandal
As mentioned, they find shelter and when it's really cold they go into an overnight trance like state and look kinda dead until morning. Also as mentioned, if the cold spell is too long they eventually give up the ghost but often people see them 'dead' and toss them in the garbage or bury them only to find out later they were likely in their trance state. Lot's of stuff in the papers and internet at this time of year and yes an incandescent bulb placed under the feeder is pretty common here.
Sounds like you want to diy but in case you or anyone else didn't know, there are several companies that sell heated hummingbird feeders. Here in the Northeast they head south, but I was surprised to hear that many winter over in your part of the world.
