Get a medium large cardboard box and put paper towels or a regular towel in it. Then get a heating pad and put that in there. That is at least a cheaply made brooder, I've done it before and it works. What predators have been trying to get to it? Be careful of coons and possums, they have nimble fingers and will try to open the birdhouse.actually, it is outside my house. It is in a bird cage, with clean food and water and a wood house where it sleeps. The predators aren't trying to kill it anymore, and I don't have a brooder. Any substitute to keep it warm?