This page contains a regularly updated diary of seasonal changes to Goulburn’s Flora and Fauna. It’s written by one of TGG’s members who has a keen scientific interest in the biological significance of the area.
Winter in Goulburn, NSW
Just as many visitors from more northerly and coastal regions thought that it could get no colder than the frosty nights in May, the Goulburn countryside showed them otherwise. Our winter nights can drop to -7°C and we often have visible frosts before 8:00 PM. The days can sometimes be as cool as 4°C, unless you count the wind chill factor, in which case the effective daytime temperature can be as low as -4°C. This can be scary stuff for folks who come from frost-free climes. But by day the air is crisp and clean, and the sun warm against a bright blue sky.
Outdoor tomatoes and other soft vegetables and flowers have by June been killed off by the frosts. It’s about now that people realise why kikuyu is not a particularly appropriate lawn species. Like other grasses from warmer areas, it turns yellow and can die off, unlike cold-hardier species. Unless there has been much rain, the combination of frost and wind create a similar effect to prolonged drought on the landscape, but much faster.
Of course frost in the Goulburn region doesn’t happen every night, but somewhere between 30 and 60 heavy frosts a year are par for the course. Sometimes there is snow and sleet in Goulburn, but a relatively dry climate and only every few years are conditions right to leave a enough covering for making snowmen and snow angels or engaging in snowball fights.
But there is a real upside to this climate. Apart from bringing on the glorious colours of deciduous autumn, apples, pears and a large variety of stone fruit need the frosts to thrive and produce the sweet fruit that many Goulburn gardeners take for granted. Even some of our introduced weeds, such as hawthorn, blackberry and briar rose, lose their leaves revealing rich juicy fruits that are avidly sought by some of our wildlife such as gang-gang cockatoos, corellas, sulphur-crested cockatoos and rosellas.
To many observers, the whole southern highlands landscape seems to have done into recess with apparently dead grass filling the void around forlorn eucalypts in the paddocks and hillsides. What is not often realised is that the grassy box woodlands around Goulburn have an unusually high natural biodiversity. At first glance they appear to contain little more than two or three species of eucalypt with a couple of wattles and lots of grass. In fact there are many species of small flowering herbs — orchids, daisies, lilies and a host of other flowers — that appear briefly and disappear again leaving no trace.
Unlike many northern hemisphere garden favourites, these little plants may not flower every year. Several species of orchid, for example, may flower once every 20 years or so to the amazement of people who by that time thought they were locals and knew all the plants around. Our woodlands have a deciduous understorey, sometimes as colourful as those large street trees from Europe, Asia or America, but usually unobserved or ignored in passing.
The sky attains deeper and more vivid shades of blue, providing bright contrast with the silvery white trunks of snow gums and brittle gums. Brittle gums Eucalyptus mannifera, also known as red-spotted gums, are fast growing in this Southern Tablelands climate and provide food and shelter to a range of wildlife. These hardy and attractive, fast-growing trees can be found on a variety of soils from moderately fertile lower slopes to poor gravelly soils of ridge-tops. Being a relatively small eucalypt they work well in gardens and make excellent features of parks standing out like the tablelands’ version of the central Australian ghost gum.
On farms they provide great habitat and pretty reasonable kindling and small firewood as they shed their lower branchlets. They have by now shed last year’s outer bark, often in colourful patches, leaving behind powdery and smooth trunks. This separates them from the similar scribbly gums Eucalyptus rossii which don’t have powdery bark but do have wrinkles in their armpits and elbows.
The Goulburn winter has its own flowers too. Urn heath Melichrus urceolatus is still in flower, as are mistletoes and cranberry heath Astroloma humifusum. Early wattle Acacia genistifolia is now prominent. This medium-sized, sweet-smelling, prickly shrub is an important resource at this sparse time, providing food for the insects and small birds still around the grassy box woodlands. Another conspicuous flowering plant in winter is gorse Ulex europaeus, a very spiny weed that is spreading along colder parts of the tablelands.
Many bird species have migrated away to warmer areas on the South Coast or inland, taking with them some of their predators such as butcherbirds. This provides an opportunity for a few birds to take the cold shift. The most conspicuous of these are the reddish robins: scarlet, flame and red-capped. These small woodland birds replace their forest-dwelling relatives the yellow robins from May to September.
Other small birds, particularly thornbills, fairy-wrens and treecreepers stay all year, but seem to be more noticeable in winter. Thornbills can be a birdwatcher’s nightmare and are often merely identified as the small brown birds (SBBs), best distinguished by sound rather than appearance. But we can visually tell them apart: a distinguishing feature of us humans is that they tend to make small birds (and almost every other animal for that matter) turn tail and flee. When thornbills disappear they display their rumps. You can identify the most common thornbills (yellow-rumped, buff-rumped and brown, which have rich chestnut rumps) this way. Those with pretty dull rumps are also obvious: yellow thornbills are distinctly yellowish, striated thornbills are covered in bold streaks or striations and the weebill (one of Australia’s smallest birds) has a wee bill and a very big loud voice for its size.
While there are nooks and crannies in which tiny insects can be found by small birds, winter makes it harder for many other animals. Biting insects, snakes and spiders have gone for their 6-month sleep, as have the little bats that fed upon small insects in the night. Sometimes small bats end up confused in chicken coops or laundries as they try to find a snug overwintering place. It is very important not to disturb either small bats or birds during their winter torpor. They may well fly away, but their small bodies have a harsh economy to let them survive the long fast ahead. Sad reports from locals tell of such small animals being ‘released’ only to see them literally drop dead out of the sky after a brief flight as their remaining energy is used up without being able to be replenished.
Eastern Horseshoe Bat
Those animals staying behind now in the Southern Highlands have to look harder for their food. Kookaburras that could easily catch prey spotted from a few fence posts now comb the woods more extensively and intently. Large marsupials like wombats and wallabies have to spend longer times eating to get the energy they need to make it through the winter. As the lush green pick in valleys stops producing new growth many wallabies, wallaroos and kangaroos find themselves higher up the hills eating less palatable shrubs and poorer grasses among infertile stringybark and scribbly gum ridges.
After a day out in biting winds it is often good to be inside in front of a warm fire. But there is a price to pay. It takes about 40 years for a typical eucalypt (10 years for a black wattle) to grow to a tree capable of providing a reasonable amount and quality of firewood, with an extra 18 months needed to effectively season it. The best firewood trees are the oldest and slowest growing. Mature yellow or red box, or red gums, can be effectively irreplaceable in our lifetimes. Bit by bit the inefficient old fireplaces and opportunistic and sometimes ignorant or unethical suppliers turn trees that should be priceless into bursts of flame and ash. And firewood is certainly not getting cheaper.
More efficient heating and better house design should have been a compulsory feature in the Southern Tablelands a long time ago. Some years ago a firewood dealer near Goulburn had a 200 acre stand of trees he set aside for his business. Every year he would clear 5 acres, leaving small trees and seedlings to regrow so in 40 years he could be back to the beginning. He had a great system. Sadly, his working life and the short cycles of real estate changed things.
Perhaps someone reading this could re-vitalise such a scheme without chopping down irreplaceable old trees to get there. Better still, why not utilise better energy-efficient design or more environmentally friendly heating such as gas (the use of this fossil fuel is actually more environmentally friendly than chopping down trees that themselves act as carbon banks as long as they stand) or heat banking or therm(systems that use local thermal differentials to store and provide heat even in the coldest weather)? Even fallen wood is a valuable resource for native animals. Some, such as the brown treecreeper, directly rely upon plentiful fallen timber to survive and hence, in our time of tidying this material away or sending it back into the atmosphere, brown treecreepers and several other native woodland birds have had to be scheduled in the NSW Threatened Species Act.