What’s in a name? This one says it all – Acrobates pygmaeus, literally pygmy acrobats. The Latin name is very descriptive, but until you see them in action, you wouldn’t know just how accurate it is.

The common name, Feathertail Glider, is also apt. Sometimes the only part of this smallest of marsupial gliders that the observer sees, is the feather-like tail, uneaten and discarded.

They may be cute, but because they’re so small, they are difficult to detect in the field. Observing their behaviour is even more tricky because they often freeze, or disappear, when a bright light is shone on them. Before I swamp you with thermal videos of these fascinating animals, you might like to see them up close:

Actually, there now appear to be two species of Feathertail Glider, the Narrow-toed Feathertail Glider (A. pygmaeus) and the Broad-toed Feathertail Glider (A. frontalis) – see A feathery-tale of a new species. To date, only the Narrow-toed has been confirmed in the Strathbogie Ranges. Mind, there is also still discussion about the validity of the new species.

The use of infra-red detection to survey for cryptic species like the Feathertail Glider has been revelatory. Here are a few videos from the nocturnal survey work we’ve been conducting in the Strathbogie Forest. Because the images are fairly dark (on purpose – to better detect ‘hot-spots’), they need to be viewed in low light. As the temperature range in the viewfinder changes, so the colour palette used to discriminate between different temperatures also changes. The device used in these surveys was the Pulsar Helion XP 28 and magnification is usually x1.4. These videos are of lower resolution that the originals files, but you should still be able to follow the progress of the gliders (though probably not on a phone) – look for the bright, white spot! If watching on a desktop, watch in ‘full screen’.

In this first video, a small animal is in the canopy of Broad-leaved Peppermints (Eucalyptus dives), only about 15 m distant. The animal stops frequently, suggesting it has found food, perhaps some honey-dew, or an insect, or is perhaps grooming, or scent marking. It runs along large branches and small, never putting a foot wrong. And it barely jumps, preferring to retrace its steps when encountering a dead-end. It’s not until the end of the video, 4:04 mins, that this little animal’s identity – Feathertail Glider – is confirmed, with a glide to the right, out of frame.

As you can see, these little fellows are constantly on the move. Being small and warm-blooded, they have high metabolic needs and need to be constantly on the move looking for food, which also means their body temperatures when active are high. Infra-red improves our ability to detect these tiny creatures, but identifying what you find can be difficult.

In the habitats we’re surveying, there are a number of small mammals that would look similar in the thermal image – Feathertail Glider, Eastern Pygmy-possum, Agile Antechinus – but only one of them glides!

This next video shows a single Feathertail Glider exploring branches and foliage about 15 m away, in the canopy of Mountain Swamp Gums (Eucalyptus camphora) near Mt Barrenhet. Watch it methodically scamper along branches and through foliage. At 2:40 into the video it glides to the base of another tree and begins a new bout of investigation.

The next video is taken nearby, along Barjarg Rd, in higher-altitude forest of Mountain Gum (E. dalrympleana), Messmate (E. obliqua) and Victorian Blue-gum (E. bicostata). There are at least two Feathertails in this video, though they are further away and a bit harder to see. At 46 seconds in, a second white dot appears briefly in the distance, most likely another Feathertail. From about 1.45 onward, the glider is foraging in the loose bark on a large Mountain Gum, periodically disappearing from view and eventually staying put under bark and out of view.

At 2.19, still from the same spot, I scan back to where I saw a small heat signature at 46 seconds and, though blurry, at 2.25 you can see one spot low in the screen and at 2.30 another spot high in the distant canopy. At 2.31 the distant spot in the canopy glides to the left (confirming it’s a Feathertail), then I pan to the right and pick up the other spot at 2.44 seconds.

Being small also comes with advantages. The videos show that even on cold nights, tree trunks and major limbs are noticeably warmer than the air temperature. No wonder having a home inside a big tree, or limb, or in cracks and under bark, especially on cold nights, provides thermal advantages for these hot-blooded little marsupials.

The last video was filmed on Crystal Mine Tk, in a luxuriant gully with majestic, 50 m high Mountain Gums. This site had it all, Sugar Gliders, Greater Gliders, owls, possums and this little fellow, who dashed horizontally along branches though the canopy, before ascending the trunk of a huge Mountain Gum that was fully in flower. Though it didn’t glide, it’s movement pattern and effortless climb high into the canopy suggests it was Feathertail Glider, rather than an Antechinus or Pygmy-possum. The night was cold, but the day had been sunny. Note how well defined the trees and branches are, due to their radiating heat.

Fauna surveys using IR technology allow perception of the nocturnal realm in a completely new way that answers some questions, but raises many more. Through our IR surveys, we’ve now recorded Feathertail Gliders at seven new locations in the Strathbogie Forest.

So, next time you’re walking in an area of bush here in the Strathbogie Ranges, or across much of eastern Australia, as long as the habitat is connected to other treed parts of the landscape, it’s highly likely you’re in the presence of these tree-top acrobats, though you may never actually see them.

This work is part of the Strathbogie Forest Citizen Science Project and also the Biolinks Alliance Glideways Project. The project is supported by the Victorian Government.