Griffon vultures can form gay couples and take care of eggs
As evidenced by some penguin couples, homosexuality within the bird species is much more common than most people think. A quick search on the internet about gay bird couples will reveal many examples of gay birds taking care of eggs in zoos or their natural habitats.
In 2017, for example, a couple of gay griffon vultures were given an abandoned egg. Their parental instincts kicked in, so they took care of the egg together. Once the egg hatched, the couple raised the chick as their own without a second thought.