Missing frogs make a comeback

Twenty years after vanishing from the rainforests of far north Queensland, the armoured mistfrog (Litoria lorica) was rediscovered in 2008 on the Carbine Tableland. Previously thought to be purely a rainforest resident, the armoured mistfrog had found a home in ecotonal areas adjacent to rainforest along a waterway in the Wet Tropics World Heritage Area.

However, only the one small population was found after five years of intensive surveys by a James Cook University team led by Dr Conrad Hoskin and Dr Robert Puschendorf.

So, in September 2013 Dr Hoskin led a team to conduct the first frog translocation in Queensland’s history, giving the armoured mistfrog a second chance at survival. The translocation team included representatives from James Cook University, the Department of Environment and Heritage Protection, the Department of National Parks, Recreation, Sport and Racing, and the Western Yalanji Aboriginal Corporation.

A successful translocation

Forty armoured mistfrogs (20 males and 20 females) were carefully translocated to a new site about four kilometres upstream from the single known population. Seventeen of the translocated females carried eggs. The translocation was a great success with many of the released frogs visible the second night sitting by a waterfall.

‘No species is safe, as a single population, when disease or other threats could suddenly wipe out that population, and hence the entire species’ Dr Hoskin explained. ‘Translocation was the best option for the critically endangered frog. Having rediscovered this species, we don’t want to lose it a second time.’

Survival and breeding success will be monitored for both source and translocated populations over the next five years to ensure that the armoured mistfrog is on track and thriving.

The project was funded through the Australian Government’s National Environmental Research Program Tropical Ecosystems Hub. It is part of a broader program assessing disappearing frogs and other vertebrates in ecotonal areas of the Wet Tropics and Eungella National Park west of Mackay.

The NERP research program is confirming that ecotonal and peripheral areas are very important for the protection and management of a range of vertebrates and highlights the need for further research into these and other refuges.

Impacts of chytrid fungus on upland stream-dwelling frogs in the Wet Tropics

While the armoured mistfrog has found a new habitat where it can better survive many other upland frog species are likely to already be extinct or remain in perilously low numbers.

Amphibian chytrid fungus has severely impacted stream dwelling frogs of the Wet Tropics over the last few decades, particularly upland species living above 500 about metres. It has likely caused:

the extinction of the mountain mistfrog (Litoria nyakalensis) and the sharp-snouted day frog (Taudactylus acutirostris)
the possible extinction of the northern tinker frog (Taudactylus rheophilus),
large declines in populations of the armoured mistfrog (Litoria lorica), waterfall frog (Litoria nannotis), common mistfrog (Litoria rheocola) and the lacelid treefrog (Litoria dayi).

If the northern tinker frog survives it is restricted to small upland populations only. Dr Hoskin has automatic call recorders at the last known sites to determine if the species persists at these. The lacelid treefrog, the common mistfrog and the waterfall frog remain common in lowland rainforest, and the latter two of these are also present at higher elevations in the peripheral dry forested areas on the western side of the Wet Tropics.

What is amphibian chytrid fungus?

Amphibian chytrid fungus causes chytridiomycosis, a highly infectious disease that has devastated wet forest frogs globally. The fungus infects keratin, a structural protein found in frog skin and tadpole mouthparts, disrupting normal physiological function and often resulting in death.

Hundreds of frog species have become extinct globally because of the fungus. As seen in the Wet Tropics, declines globally have been worse in higher elevations where the fungus thrives in damp, cool conditions. It is hoped that Dr Hoskin's and Dr Puschendorf’s findings in dry peripheral areas of the Wet Tropics will assist in the rediscovery and management of threatened frogs globally.