THE HAGUE, Netherlands (AP) — Two male griffon vultures in a long-standing relationship have successfully hatched an abandoned egg at an Amsterdam zoo.

Artis zoo said in a statement Wednesday that keepers who found an egg found on the floor of the vulture aviary initially put it in an incubator but later placed in a nest that the two male birds built together in the enclosure.

The zoo said the vultures, which have been a couple for years, took turns sitting on the egg until it hatched. Now, the new dads are taking care of the chick by feeding it regurgitated food.

The zoo says it is not unusual for animals, particularly birds, to form same-sex couples, but it is the first time such a pair has hatched an egg at the Dutch capital's zoo.