To keep my Thanksgiving 2006 Allen's Hummingbird happy, I bought a small clip-on outdoor reflector, fitted a regular 60W bulb, and shone it on the HummZinger Mini feeder from about a foot above. This worked fine at the lowest temps the bird saw, about 17°F. This is the most common solution, and also proves a warm perch. The syrup doesn't need to be hot, only above freezing--steaming is too warm. Adjust the distance as required.
Other proven tactics include wrapping a feeder in heat tape, and setting a feeder in a heated doggy bowl. Any of these works better than getting up at first light, when freshly-awoken birds are at their neediest, to hang a thawed feeder. Personally, I would not want to risk oversleeping, then finding a dead Rufous under the feeder. Just sayin'.
FWIW, a 1:3 syrup freezes only about 2°F colder than 1:4. I used to recommend 1:3 in winter, but now I don't think it's worth the bother.
> On Nov 11, 2019, at 13:49, WILLIAM R EDDLEMAN <eddlemanw...> wrote:
> Someone I know who overwintered a Rufous used hot water bottles strapped to the feeders to delay melting.