Yeah it's been a bad year for outside kept birds weather's been too cold. I've heard of some hens coming off the nest leaving young. Then some young not eating because of the cold not enough energy stored up. This chap in question put a 20watt lamp under the nest. The chicks came good an started feeding again ?. It's crazy. I've just had these little diamonds hatch 3 Isabel pastel goldfinches there's another two eggs to hatch yet. I've got these in my house in my spare room I've made into a birdroom heating and lighting another hen I've got on 4 more eggs ready in next few days