Conservationists pin hopes of the species’ survival on breeding the Caribbean island’s last known male and female in the wild–Jessica Aldred reports for London’s Guardian.
In what could be a fairytale ending, conservationists are hoping to reunite the last two remaining wild mountain chicken frogs living on Montserrat and help their species breed on the Caribbean island for the first time since 2009.
A project led by the Durrell Wildlife Conservation Trust will next month take the last remaining female and “translocate” her into the territory of the last remaining male as part of a 20-year recovery plan for the species, one of the world’s largest and rarest frogs that exists on just two Caribbean islands, Montserrat and Dominica.
The two frogs are the island’s only known survivors of an outbreak of the deadlychytrid fungus disease, a pandemic ravaging amphibian populations worldwide.
Montserrat’s remaining male and female live roughly 500m apart among the boulders of a steep, fast-flowing stream in the rainforest. Over the next few weeks, the team of conservationists will first try to locate the male by his deep, whooping mating call, which begins as the rains of the breeding season start to fall. Then they will try to find the female further downstream.
Providing the two can be found, the team will move the female into the male’s territory and set up a few artificial nests to encourage her to stay. There will be several weeks of intense monitoring where two conservationists will hike for an hour to and from the stream and spend around six hours every night keeping watch on the female to make sure she hasn’t moved back to her old home.
The ultimate hope is that over the next four months of the breeding season, the two mate and nest, something that has never before been observed in the wild on the island.
“The best chance for them breeding is in the wild in their native habitat – it’s just a matter of getting them together,” said Jeff Dawson, amphibian programme manager for Durrell and project coordinator for the mountain chicken recovery programme, which also involves ZSL, Chester zoo, Nordens Ark in Sweden and local governments.
“Now it’s started raining I’m confident that the team out there will do their best to locate the frogs and the translocation will go ahead. After that it’s out of our hands, all we can do it let nature take its course.”
Dawson said the project had encountered early reluctance from some conservation groups who were concerned about interfering with the frogs. Attempts to reunite the frogs last year were thwarted by an unusually dry wet season in which they couldn’t be found.
“We thought about bringing them into captivity but the risk is much greater with stress and transportation and they are tricky breeders in captivity. These are potentially the last two remaining frogs in the wild. If they stay where they are now, they won’t breed and will eventually die and that will be the last we will see of their species.
“If you move them together there is the potential they won’t breed or something else will happen. The outcome would still be the same as not doing anything but there is that chance that they will breed.”
The frog is ecologically important: Montserrat and Dominica have no native terrestrial mammals, so it acts as a top predator. It has a voracious appetite and anecdotal reports from farmers cite an increase in insects corresponding to the crash in frog numbers. It is also culturally important to the islands.
Years of overhunting and habitat loss, as well as volcanic eruptions in Montserrat, had already reduced numbers of the frog, which was once found on many eastern Caribbean islands. Then chytrid fungus arrived, devastating Dominica’s population in 2002 and reducing numbers from of tens of thousands to around 200 when it reached Montserrat in 2009. There are now thought to be less than 100 individuals left in the wild.
Chytridiomycosis, described by scientists as “the worst infectious disease ever recorded among vertebrates,” has so far infected more than 600 amphibian species globally, causing population declines, extirpations or extinctions in more than 200 species. It spreads via spores and affects the skin of amphibians — through which many drink and breathe — leading to cardiac arrest.
Dawson said it was not known how these two survived the chytrid outbreak, but that the ramifications for fighting the disease were huge. “They may have native immunity or natural resistance to disease – we know of frogs on Dominica that survived chytrid as well. The fact that they survived tells me that their offspring would be genetically resistant, which would be fantastic in terms of trying to build up the population on Monserrat.”
The recovery programme has been working with captive breeding projects in four zoos and in-situ conservation since the disease hit and next steps include plans for semi-wild enclosures where they can test the ability of captive-bred frogs to fight the disease in carefully controlled conditions.
“Chytrid is not going away, it’s all over the island – so until someone finds a cure for it, we need to look at how we manage the environment so that populations can survive. If we can find a way to save this species and help it recover, the information we learn will be really important and useful for other populations of amphibians around the world.”