The drop in the number of moths leaves the possums of the Pygmy Mountains hungry | Environment

A considerable number of unique Australian butterflies, which per billion migrate into the Alpine regions, have crashed, according to environmentalists, putting additional pressure on the endangered mountain pygmy possum.

Scientists believe that the "astonishing" decline in moth numbers is related to climate change and recent droughts in the breeding grounds of these moths.

At the same time, controls on the endangered mountain possum, which only exists in alpine regions of Australia, have revealed dead litters in female pockets. Moths are an essential food source for possums on the eve of their hibernation.

In 2018, scientists revealed that moths were the only known insect to use the Earth's magnetic field to help navigate the meadows of northern New South Wales and southern Queensland, sometimes at distances of 1,000 km. About two billion butterflies are supposed to make the trip.

Ecologist Ken Green has been monitoring nocturnal moths for 40 years. He said: "Last summer's numbers were atrocious. It was not only really bad, it was the worst I had ever seen. Now this year the situation is even worse. "

Moths find caves and cracks in the rocks to hide in a state of torpor. A cave on Mount Gingera, near Canberra, would have housed millions of moths, but last month Green and his colleagues counted only three people. Research on about 50 known sites has resulted in similar catastrophic absences.

"They did not just refuse. They are gone, "he says. "We have traveled mountains from the Victorian border to Canberra. We checked all the caves we know.

Last year, a site in South Ramshead, in the Snowy Mountains, NSW, had only 1,000 butterflies. "It's very, very low," says Green.

"This year, we only found six months. We came back last week and there was none.

Green thinks that the cause of the crash is the drought in the butterfly breeding areas. The Bureau of Meteorology said the drought was exceptional in these areas, but noted that there had been similar dry periods in the 1960s and before.

Impact on possums of endangered mountain pygmies

Dean Heinze, a partner at Latrobe University, has been monitoring and studying mountain pygmy possums since the early 1990s. Opossum populations are distributed in Kosciuszko National Park, New South Wales, and in Victoria, Mount Bogong, Mount Higginbotham and Mount Buller.

When possums emerge from hibernation in September and October, moths are an essential food source for breeding and rearing young.

"The moths are an amazing food source and very rich in protein. Last year, we found that some oposs populations were losing litters. This is happening again this year. We think that fewer moths means that the possums weigh less and lose the litters. "

In recent weeks, Heinze has visited about 12 sites in Victoria and found dead litters in women's pockets at "most sites".

"It's a very common event," he said. "I'm inspecting the breeding system of the animal and I look in his pocket to see how many young people there are. I opened pockets and discovered dead and decaying young people … For some, young people have been dead for days.

"The concern is that over time, if this occurs more frequently, we will also witness a decline in the adult population. And it's the second year that they have lost litters. The decisive test will be next season. "

Around Mount Buller in Victoria, the possum habitat is fragmented by ski resorts. Captive breeding and release programs were used to maintain the numbers.

"We have put considerable effort into the population of Mount Buller," said Heinze. "We have brought the population back from the brink and that is happening now. I'm optimistic, but if we get more, it does not look good. It is a species that only appears in the Alps, but whose impact occurs hundreds of kilometers away. "

In 2016, a national recovery plan was adopted for the possum, outlining multiple threats, including habitat degradation, predation by cats and invasive foxes, and climate change.

A study published in October 2018 and led by scientists from the New South Wales Environment and Heritage Office examined the threats of climate change to possums and moths. The study suggests that butterflies have "reduced survival in a warmer world", which "would probably affect survival more" of possums.

Lesley Hughes, an ecologist at Macquarie University and a consultant to the Climate Council of Australia, said ecologists and climate scientists predicted the potential role of climate change in the decline of butterflies and opossums.

"Unfortunately, the general predictions of the ecological risks of climate change are now turning into observations for particular species. And it should not be surprising that we observe these impacts in the alpine zone, long recognized as one of the most vulnerable ecosystems to climate risks.

"Sometimes these changes may seem to happen suddenly – a year, there are millions of moths and almost none at all. This shows how particular extreme events, such as droughts and bush fires, can tip one species at a time, and impact other ecosystems. "

Environment Minister Melissa Price said she was aware of reports of a small number of bogong moths and that the government was working with a leading researcher on the subject. Oposs to "understand the potential cost of a reduced number of moths on the species".

The elimination of wild cats and foxes in Kosciusko National Park contributed to the protection of possums, and two government-supported projects tackle weed infestations, strengthen resilience to climate change, and manage the loss of genetic diversity among the possums of the Victorian Alpine region.

Victoria's Environment, Land, Water and Planning Ministry spokesman Adrian Moorrees said the reduction in the number of moths "is probably due to recent droughts". NSW and Queensland.

He added that tools and processes were being developed "to better monitor and predict the impact of moth populations on endangered mountain pygmy possums".

A spokesman for NSW's environment and heritage office said no waste deaths have been reported among NSW possum populations, but that the drought would have affected most species.

He added that when the number of butterflies was low, the possums turned to other food sources, including insects, fruits and nectar, adding that "the OEH would continue to implement the species recovery plans for the mountain pygmy ".