As It Happens

Romeo, the 'world's loneliest frog', and new mate Juliet have coupled

The stars appear to be aligning for Romeo and his Juliet, with researchers encouraged by the Sehuencas water frogs' first attempts to reproduce.

The rare Sehuencas water frog is showing signs of being smitten, performing a 'twinkly toes' dance

Romeo, once dubbed 'the loneliest frog in the world', with his auspiciously-named potential mate, Juliet. (Submitted by Global Wildlife Conservation)

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Until a few months ago, Romeo was believed to be the world's loneliest frog — perhaps the last of his species.

But a super-rare female Sehuencas water frog was recently discovered as a potential mate. And now, after being screened for fatal diseases, she's been introduced to Romeo.

Sophia Barron, head of conservation breeding at the K'ayra Center at the Museo de Historia Natural Alcide d'Orbigny in Bolivia, where Romeo and Juliet are under observation, spoke with As it Happens host Carol Off about the amphibious couple's coupling.

Here is some of their conversation.

Sophia, we know this is early days. But how did the first encounter between Romeo and Juliet go?

Oh, it was amazing. Both of them are doing great. And Romeo is trying to do amplexus. Amplexus is the mating position — the "embrace" position for frogs. So he's trying to do it. The longest was 15 minutes. But now, he's like ... during the day, he'll do amplexus for a few times, and then it stops.

But the couple is doing great.

OK, so he's getting up to speed, then. I mean, he's been — we've called him the loneliest frog in the world. Has Romeo ever had a mate in the past?

No, never. We thought he was the last from this species.

How is he around Juliet? How does he respond to her?

First, we chose Juliet because from all the five frogs that we collected, she is the biggest. And we can see that she's producing eggs. So she's ready to reproduce. 

And we heard for the first time a courtship call. That means that Romeo starts singing before going into amplexus. So he calls when he's close to Juliet. So that's a really good sign that they are doing great.

'Frogs on a dinner date': a Romeo-and-Juliet-inspired illustration by Eric Losh.

Now, I understand that Romeo also does something pretty interesting with his toes you never saw before.

That was super funny. It was something that we never expected to happen.

We call it, like,"Twinkle Toes." It's like his toes are making a dance. 

It's the first time we've recorded these reproductive behaviours. It's the first record for all these groups of frogs.

Now I know that you are ... giving them some privacy, but you're watching this pretty closely. So ... do you know, the Sehuencas frog ... how do they do it?

Yeah, we are giving them privacy, but we need to check them every day. We need to give them food and also check the water quality. Because these frogs are aquatic frogs. They breathe through their skin, and they exchange all the ions through the skin also. So all the parameters of water quality have to be perfect for them. 

And also, something important for reproduction is the temperature. 

The female releases the eggs. At the same time, the male releases the sperm into the water. The fertilization happens in the water.

Successful field collection of Sehuencas frogs. ( Global Wildlife Conservation)

Have you seen them do it? I mean, are there eggs? Is there sperm? Is there something happening?

We didn't see eggs yet. But every day that I go to check them and to control all these conditions, I'm really excited to see the eggs. So I hope it will happen soon.

We should point out that there is a lot riding on this relationship, isn't there? I mean, an entire species of frog needs to see these two get intimate. So ... if they can't reproduce, if they can't have any babies, what happens?

We have a lot of options. First of all, we have two more couples [of] Sehuencas water frog. We saw that the males and the females are ready to reproduce.

So we have the option to try with the other four frogs. And also, we have the chance to change the frogs. Maybe Romeo can reproduce with the other two females.

And the last option that we have is that we've talked with a university from Australia to collect and freeze the sperm from Romeo. 

So once we have the sperm of Romeo, we can reproduce in vitro.

There are lots of things that are killing off the frogs in Bolivia. Are you worried that if you can get some breeding going — some children here for Romeo and Juliet — that they may not survive when you put them back in the wild?

Yeah. First of all, we need to mitigate all the threats that are in their natural habitat. It could be [deadly disease] Chytrid, loss of habitat, it could be pollution. We don't know.

So first, we have to study all the threats. Then work on it to try to mitigate. And then we are going to put Romeo and Juliet's grandchildren into the environment.

This is the future plan. This is the next step after Romeo and Juliet reproduce.

Written by Kevin Ball. Interview produced by Ashley Mak. Q&A edited for length and clarity.