All birds lay amniotic eggs. The yolk is used to give nutrients to the growing embryo. A lot of people mistake the yolk as the developing bird but that isn’t the case. The albumen is used to give extra food while the allantoic helps in gas exchange and the removal of waste. The amniotic fluid cushions the embryo.
These eggs are hard-shelled and are able to be laid on land.
There have been cases of same-sex birds that try to raise an egg together.
“Same Sex Parenting in Birds”
A Study In Biology 