Monday, 16 May 2011

The Pragmatic Pygmy Possum


Good "inside" weather: But what's it like outside? (Lake Dobson, Tasmania)  
The day started well. If it's going to be cold and wet, you may as well have something to show for it. And we did. Kunanyi/Mt Wellington was coated with snow to low levels. As we drove towards Mt Field National Park for the weekend, more mountains, from Domedary to Collins Cap, and Trestle to Field East, were looking at their best, a fine mantle of snow over the shoulders of each, and down to the surrounding hilltops.



We'd forgotten, however, that the same beautiful snow might make it a little difficult driving our two-wheel drive vehicle all the way to the ski hut at Lake Dobson. An ignominious retreat, a delay, and a lift up the mountain in our friend's 4WD eventually got us up to the snow-bound hut.

While the temperature hovered around zero, and snow flurries added to the already good ground cover, we revived ourselves with hot drinks by a warm fire. My thoughts turned to those caught out in this weather with no such luxuries, in particular the native animals which call the mountains home. How did they cope in weather like this so early in the season?

Then Phil walked in carrying a bucket of wood shavings. These are kept in the hut toilets and are used to help aerate the composting toilet waste. Three furry grey blobs, each about the size of a hacky sack (or for the Potter-philes, a small snitch) huddled in the bottom of the bucket. Pygmy possums!

To be precise eastern pygmy possums, Cercartetus nanus. These featherweight marsupials weigh between 15 and 40 grams, and stretch to maybe 90 mm in length, excluding the tail. They had apparently climbed into the buckets for warmth, and to shelter from the early and heavy snow, and had become trapped.


A sleepy eastern pygmy possum shows us it's alive (photo by Lynne Grant) 

We pick the little creatures up to check for signs of life. Disproportionately large dark eyes blink at me, whiskers slowly twitch, and a rapid heart beat flutters faint against my hand. Finally its long, bare and exquisitely curled tail unwinds. Pygmy possums use their tails to help them climb around the forest canopy, where they feed, mainly on nectar. However they are also known to take invertebrates, including moths, which they can spot at night using their large and sensitive eyes. 


Another member of the Burramyidae (pygmy possum) family is the mountain pygmy possum, which famously feasts on bogong moths in the Australian Alps every summer. That mountain variety hibernates for much of winter. With weather as fickle and occasionally freezing as that in the Tasmanian highlands, eastern pygmy possums have opted for mini hibernation, or torpor, during cold spells rather than full hibernation.

Their body temperature lowers close to the ambient temperature, and their metabolism drops correspondingly, decreasing their need for energy inputs. Torpor lasts from a few days to a few weeks, perfect for the “here today, gone tomorrow” nature of snow in Tasmania.


A furry hacky sack with whiskers: the rotund figure of an eastern pygmy possum
The eastern pygmy possum was first described by French naturalist Francois Peron in 1802. Peron collected a live pygmy possum from an Aboriginal man on Maria Island, in exchange for some trinkets. The Frenchman was of the opinion that the Aboriginal man was going to cook and eat the tiny mammal – hardly a square meal!

Our hut-visiting pygmy possums don’t seem unduly concerned at our handling of them, and when we reposition them in a shallower container, they simply shuffle close together and continue their slumber.

We check the “fur kids” several times in the early evening, as much smitten by their furry charms as for any real help we might have offered them. When it’s bed time for us, we put their open container out in the vestibule, and leave them to it. We figure, correctly, that they will move on during the night.

As I settle into my sleeping bag in the near-to-freezing bunkroom, I shiver for the first minute or two, waiting for the down bag to have its effect. In that moment I envy the pygmy possum its ability to curl into a ball. And as the wind thumps into the side of the hut, and whistles through the door and window cracks, I start to see why the occasional period of torpor might have a lot going for it.
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