For years now, the Artis Amsterdam Royal Zoo has been home to a monogamous couple of male griffon vultures. They live together and nest together.

But, since they're a same-sex couple, they've never been able to have vulture babies — that is, until zookeepers found an abandoned egg.

Job van Tol, a zookeeper at the Artis Amsterdam Royal Zoo, introduced the abandoned egg to the couple, who had already started a nest. And now they have a baby bird of their own.

As It Happens host Carol Off spoke with Job van Tol about the new family. Here is part of their conversation.

CO: Where did you find this abandoned vulture egg?

JV: Vultures are really close to one another. They're monogamous animals.

Normally, they build a nest and then lay an egg. But this one I found on the floor of the aviary. So that was a little different. So I found it and there was no vulture breeding it. For safety reasons, we put it in the incubator and we were, of course, also curious on whether it would be fertile or not. And it was.

CO: How did you find some parents that may be willing to nurse that chick?

JV: Well that's the beautiful story. We have several strong couples in our aviary. And also for years we've had a male couple in our aviary. And that happens a lot in the bird world — same-sex couples are really quite normal.

Every January, they would start building nests and mate, and of course, unfortunately, being two guys, they weren't able to produce an egg. Knowing this, we thought immediately this is the perfect opportunity for these male vultures to actually give them a fertile real egg and give them the opportunity to maybe hatch and raise a chick. So that's kind of unique. It never happened before.

CO: You gave them this fake egg for all these years, and you determined from that that they were nurturing, that they would care for this egg?

JV: Yeah, and they took it very seriously. We let them build up experienced in breeding. We know that they did perfectly all the time.

We replaced it and we gave them the real egg. After a couple days, you know, we were curious, and a little bit nervous. We climbed up the rock to take a little peek and see what happens. Then we saw this little chick moving under these brave guys, and that was an unbelievable sight.

CO: What are they doing as parents?

JV: One of them is staying on the nest, keeping the chick warm, protecting it from other vultures ... and the other one goes out to forage for food. And when it comes back, they can alternate their tasks.

And that's also why two males are capable of raising a chick. There's no difference between a female role and a male role, for example. So that's why it's not that weird, you know? The DNA in the male griffon vulture is built in to raise a chick, so two males are perfectly capable to doing so.

CO: And the chick is doing well?

JV: The chick's doing fantastically.