Wild birds are always attracted to heat.Parking lots in winter are loaded with little birds hopping under cars on warm pipes to keep warm.Many wild birds die in the winter,some can take the hardship,others can't.
I use many cozy coop heaters to keep temps comfortable,only positive things happen,mainly they are comfortable when in the coop.They have air conditioning in summer,because no shade for ,coop anyway..
Yes power has gone out,several times for hours,nothing bad happened.They play outside,no they don't get sick.All myths.
They lay more eggs though,that's a fact.