Linda Broome pulls herself up a nearvertical slab of granite, leaps nimbly over a snow-lined fissure, and dives head-first into a crack in the rocks. At 67, she knows Blue Cow Mountain like the back of her gloved hands. Every November for the past three decades, she has led volunteers up this 1,901 metre peak, and a handful of other high-altitude boulder fields in the Snowy Mountains. The team visits to monitor the population of critically endangered Burramys parvus.
It's springtime in the high country. Drifts left by a late snowstorm are melting, and frogs croak enthusiastically in the fens. The nocturnal possums have hibernated under the snow all winter, dropping their body temperature to just above freezing for up to seven months. Then, a few weeks ago, they woke up. Broome, a threatened-species officer at the New South Wales state environment department, retrieves a rectangular aluminium trap from the crack and backs out. She carefully reaches inside, past a lining of cushionstuffing, and retrieves a whiskery, mouse-like creature with black eyes and brown-and-gold fur.
She holds it by the base of its long, scaly tail, which curls around her finger. “It's alright, darling,” she coos. “You're so sweet.” Broome and volunteer Carlie Armstrong work together to insert a minuscule microchip into the folds of skin at the possum's neck, clip a snowflake-sized disc of skin from its ear for genetic analysis, and check for parasites.
They place the creature in a cloth bag and weigh it: 34 grams. This one is female, with a handful of jellybean-like joeys in her pouch, and seems unconcerned as she perches on Broome's finger and sips water from a bottle lid. While Armstrong uses the metal trap pin to nudge the possum's droppings into a vial, Broome releases the animal. She scurries over the neon lichen and disappears into a crevice.
The little marsupial's dual mission for the coming summer is to raise her young while doubling her body weight, so she's fat enough to hibernate again. Fortunately, breakfast has arrived on her doorstep.
Every spring, vast numbers of bogong moths (Agrotis infusa) migrate as far as 1,000 kilometres from the western plains of NSW and Queensland to the Australian Alps, crawling into caves and among the rocks to avoid the heat – a summertime form of hibernation called aestivation. The alpine possums eat other invertebrates, as well as fruits, seeds, and nectar, but the fatty bogong moths are their favourite food; at the highest elevations, the migrating moths make up as much as 50% of their diet. “It's a massive movement of protein into the mountains,” says Broome – one that feeds not just possums, but ravens, lizards, and other small mammals.
In the past few years,
