The Krefft's Glider, one of Australia’s most endearing nocturnal marsupials, is a master of the night. With large eyes and thick grey fur, these tiny mammals can glide distances of 50 metres or more, spreading their limbs to expose soft membranes – known as patagia – and traversing from tree to tree under the cover of darkness.

Thanks to this remarkable soaring ability, Krefft's Glider (previously known as the Sugar Glider) rarely descend to the forest floor. Living in small social groups, they nest in tree hollows lined with fresh gum leaves – a characteristic marker of their presence.

The distictive, clean nest of a Krefft's Glider (Petaurus notatus). Photo by Chris Cobern, MCMC.

“Krefft's Gliders have unique nests that you would never confuse with the nest of another creature” explains Chris Cobern, Upper Merri Landcare Coordinator.

“They’re always very clean and lined with fresh gum leaves – but no feathers or bits of bark. It’s very interesting because they’re quite long-lived mammals, and they have very nice, neat, hygienic nests. For some of the other animals, like phascogales, which don’t live as long, hygiene isn’t a priority. They have very messy nests full of their droppings (scats) and all sorts of materials.”

Krefft's Gliders are relatively common and are known to occur in the northern end of the Merri Creek catchment. But for all their homemaking instincts, they face a significant challenge: the loss of mature, hollow-bearing trees, crucial to their shelter and survival. In response, Merri Creek Management Committee (MCMC) is supporting the formation and work of new groups such as the Upper Plenty Merri Catchment Landcare Group, to create new habitat opportunities in the area.

While MCMC has historically focused much of its work on the inner-northern catchment, the Upper Merri and Upper Plenty offer unique opportunities to protect biodiversity in areas that still include some remnant habitat.

Providing homes while natural hollows mature

Planting and revegetation efforts will eventually provide the necessary habitat for Krefft's Gliders, as well as other wildlife like treecreepers, nightjars, parrots and possums. However, these newly planted trees may take decades to mature. In the meantime, nest boxes are filling the gap.

Chris Cobern, MCMC's Upper Merri Landcare Coordinator.

In May 2024, the Upper Plenty Merri Catchment Landcare Group launched a project to install nesting boxes at Dry Creek Reserve. With donated timber and detailed design instructions specifying box and entrance dimensions for a range of species, an enthusiastic group of Landcare volunteers turned out to build the boxes.

“The establishment of our Landcare group, which is still quite new, was spearheaded by MCMC and our local Shire, with additional support from local environment groups,” says Michael Watson, Secretary of the Upper Plenty Merri Catchment Landcare Group.

“MCMC (and Chris Cobern in particular), has been invaluable in helping us get established and achieve our goals. Chris helped us plan the nest box installations and organised a nest box building activity for the group, which was very well attended. We had a wide range of people come along, including families and couples, and we built more boxes than we actually needed for the Dry Creek project so everyone got to take one home as well. It was a real community effort.”

With the nest boxes now in place, Chris will undertake annual monitoring to track their success. Each one is GPS-marked and documented to ensure easy follow-up. “We have a special camera we use to check the boxes without disturbing the animals,” Chris explains.

“Krefft's Gliders actually have a few nesting sites within their home range, and don’t use the same nest every night. Sometimes you’ll see evidence that they’ve been there, and other times you’ll see the gliders themselves. Once, on a different site, I checked a box and found eight Krefft's Gliders all tucked up in one box. There were a few young ones in there all cuddled up together.”

Rebalancing the ecosystem

The nest box project does more than just provide homes for native wildlife; it plays a crucial role in rebalancing the local ecosystem: Krefft's Gliders are known to pollinate native plants and help balance factors such as mistletoe, a parasitic plant that can operate within an unbalanced system to overwhelm trees in the absence of natural checks.

“By having Krefft's Gliders and other possums in the area feeding on the mistletoe foliage, fruit and flowers, we’re helping to maintain a balance,” said Chris. “In areas without natural hollows, these animals can’t live there, and mistletoe can become too plentiful, especially in agricultural settings. Nest boxes help bring that balance back.”

Since its inception in late 2022, the Upper Plenty Merri Catchment Landcare Group has grown steadily, tackling a range of projects to improve habitat quality and increase biodiversity. Their efforts have included revegetation projects and weed management, with a focus on engaging a broad demographic.

“Our community response has been fantastic – and that momentum is still building,” says Michael. “As our membership and our interests expand, we look forward to more projects on the Merri Creek. People may not always have time for committee roles, but they’re eager to volunteer for planting days or special events like the nest box workshop. It’s rewarding work, great fun, and it contributes to improved environmental outcomes.”