The story of an assisted reproduction

Rainette faux-grillon © Biodôme de Montréal
The story of an assisted reproduction

Two grams, that’s the weight of the eleven species of frogs living in Québec – but living for how much longer? An important link in the biodiversity chain, the frog plays a unique ecological role. It devours a great many insects, and is itself prey for a number of other animals. Allowing it to disappear means allowing the chain that we human beings are also part of to grow weaker…

A frog with an outsized song!

In Canada, the chorus frog is present in the southernmost part of Ontario and Québec, which is the most northerly portion of its natural range, the majority of the population inhabiting the United States. Mating occurs in April, after the males, gathering by the hundreds in forest ponds, have enticed females there with their deafening song. Eggs that are laid turn into tadpoles in six days. A few weeks more, and the little frogs climb out of the ponds.

A plummeting Québec population

1950 : hundreds of ponds in Montérégie are brimming with thousands of frogs, and their song can be heard everywhere. 2000: the chorus frog is listed as a “vulnerable species” in Québec; then, in 2010, as an “endangered species” in Canada by COSEWIC. Scientists from the Ministère de la Faune estimate that over 90 percent of this species has disappeared. The surviving populations are far from safe. Often located on private land, they’re still threatened by urban sprawl and land drainage. Small local populations remain, but their isolation prevents the genetic exchanges essential to their long-term survival.

Reproducing frogs in captivity

The Biodôme made its first attempt at reproducing this frog in 2008. With the support of the Ministère de la Faune, a small population of tadpoles was raised in the Biodôme facilities. After hibernating in the basement fridges, the frogs were placed in large naturalized containers. No reproduction took place. In the years following, even with the addition of specimens collected from wetlands threatened by construction, and despite every effort to re-create the natural environment (rain, drizzle, change of temperature and lighting…), nothing. In early 2014, the Biodôme team got in touch with Dr. Vance Trudeau, a professor-researcher in endocrinology at the University of Ottawa whose recent work had caught our attention. He’d developed a method for reproducing amphibians that had enjoyed a lot of success with, among others, the leopard frog, another species difficult to reproduce in captivity. Enthusiastic about the idea of helping a new species reproduce, and an endangered one at that, he involved himself in developing his “love potion,” a mixture of a hormone and a dopamine antagonist.

Songs…and more!

A little injection, the males started singing in chorus, and the mating began. In 24 hours, hundreds of eggs were laid. Currently, about 600 tadpoles are completing their development at the Biodôme, and a few of them have started their metamorphosis into little frogs. A success that’s exceeding our expectations!

A crutch, but…

Our ultimate goal is to reproduce all the species without resorting to artificial means, but in some cases the right conditions have yet to be found. We know now that to get a greater quantity of chorus frogs we can count on this easy hormonal method, which is non-stressful for the animals. We wanted to reproduce frogs for an eventual project involving recolonization of natural environments, deserted but suitable for the species, in agreement with the Ministère and the recovery plan in Québec…and we’re highly satisfied with the result!

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