Australian researchers say a world-first method to get an endangered frog species "in the mood to mate" could be a vital way of saving endangered amphibians across the world.
The northern corroboree frog, found in cold, highly-elevated parts surrounding Canberra, are under threat from feral pigs and horses, fire, drought and forestry operations.
An added challenge for boosting numbers of the frog is a strong mating bias in captivity, which has meant less than a third of males have success in mating.
Far from the romantic cues of dimming the lighting or putting on sensual music, this project has involved putting hormones onto the bellies of frogs to boost desire.
As part of a four-year trial, University of Wollongong (UOW) and Taronga Zoo experts administered the hormone topically on the frogs as they were paired for breeding.
So far, more than 800 offspring at different developmental stages — as eggs, tadpoles and young frogs — have been released in the Brindabella Ranges on the NSW/ACT border.
UOW reproductive biologist Dr Aimee Silla said getting frogs in a frisky state was a challenge when breeding them in captivity as they needed "a little bit of a nudge".
"They are so finely-tuned into environmental stimuli to actually get their hormones going and basically get them in the mood to reproduce," Dr Silla said.
"All animals need the right cues, whether that's environmental cues, so temperature, rainfall or humidity. Reproduction is a lot more complex than it might appear to be."
Dr Silla said while the breeding program was only possible in captivity, it would help boost the number of offspring and their potential to adapt to threats.
"It's about putting as many offspring into the wild as possible and with as much genetic diversity as possible so that we can try and recover the species in the wild," she said.
"They can hopefully then do their thing unassisted and once there's enough of them breeding again in the wild then we can kind of take a step back and hopefully we won't have to intervene in the future."
Potential for expansion into developing world
The synthetic gonadotrophin-releasing hormone is the same used in IVF and is traditionally applied as an injection through the skin.
But Dr Silla, who worked alongside Dr Phillip Byrne said putting the hormone straight on the stomach eliminated the need for an injection and was more easily absorbed.
"The really great thing about this protocol is that it's easy, it's user-friendly, cost-effective," she said.
"And we're really hoping that not just for the northern corroboree frogs, but for threatened species globally, this protocol can be taken onboard.
"Particularly in developing countries where they might not have as much access to the training required to inject animals safely."
