Two male vultures have “adopted” a baby bird in an Amsterdam zoo.

In a statement Wednesday, Artis zoo in Amsterdam said that zoo keepers found an abandoned egg, the Associate Press reported. They initially put the egg in an incubator, but then they put it in the nest of two griffon vultures.

According to the zoo, the vultures have been in a “long-standing relationship.”They were both animal trafficking victims from Spain and brought to Amsterdam in 2010.

The two birds took turns sitting on the egg until it hatched. Now, they are feeding it regurgitated food to care for it. The zoo said it is not unusual for animals to be in same-sex pairings, but a same-sex couple parenting a baby together is a first for them.