About Me

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Canberra-based naturalist, conservationist, educator since 1980. I’m passionate about the natural world (especially the southern hemisphere), and trying to understand it and to share such understandings. To that aim I’ve written several books (most recently 'Birds in Their Habitats' and 'Australian Bird Names; origins and meanings'), run tours all over Australia, and for the last decade to South America, done a lot of ABC radio work, chaired a government environmental advisory committee and taught many adult education classes – and of course presented this blog, since 2012. I am the recipient of the Australian Natural History Medallion, the Australian Plants Award and most recently a Medal of the Order of Australia for ‘services to conservation and the environment’. I live happily in suburban Duffy with my partner Louise surrounded by a dense native garden and lots of birds.

Thursday, 28 September 2017

Undara Lava Tubes #1; volcanic landscapes

Australia, uniquely as a continent, has no active volcanoes (we don't count the sub-Antarctic island territories in this). We sit securely within the tectonic plate we ride, and the deep-seating grumblings and belches that produce volcanic eruptions and earthquakes tend to occur where two plates rub up against each other. Of course it was not always thus here, and there are plenty of extinct cones and remnants, quite a few of them well within human times. The most recent ones, in south-eastern South Australia and western Victoria, only fell silent a few thousand years ago. 

A series of volcanic landscapes dot the south-eastern hinterlands, including the Glass House Mountains, the Nandewar Range (Mount Kaputar NP), the Warrumbungles and Mount Canobolas, which erupted as Australia sailed north over a 'hot spot', which burst through as weaker or thinner sections of crust passed over it. Accordingly they get younger from north to south (from around 26 million years for the Glasshouse Mountains to 12 million for Canobolas).
Mount Canobolus, south-central New South Wales.
Undara, in north Queensland, is much younger however, dating from a mighty eruption some 190,000 years ago. 
Looking to Mount Undara, the centre of the eruption, across the woodland plains
from the rim of Kalkarni Crater. A walking track circumvents the Kalkarni rim and we shall come back to it.
It is said that more lava was produced here than by all the Hawaiian volcanoes; I have no idea if this
is true, or even what it means, but perhaps if you're familiar with Hawaii it might be helpful...
Other figures cited by presumably reputable sources are that the flow rate was sufficient to fill 1500 semi-trailers a minute (always assuming they didn't melt or explode of course), or Sydney Harbour in six days. It's unclear however how long this went on for, but the greatest extension from the source was a mighty 160km to the north-west. What is clear however is the legacy - the wonderful tubes. Where the lava flowed along river beds a rough cylinder of molten material formed; the exposed surface cooled and hardened while the insulated molten core flowed on and eventually out, leaving the hollow tubes. Undara is the longest volcanic tube system in Australia and the longest 'recent' (undefined) such system in the world. In time sections of the tube roof collapsed, forming open-ended caves, and it is some of those that we can visit, within the Undara Volcanic National Park. 
One of the Undara tubes which is open to the public.

Approximate location of the Undara tubes, some 300km inland from Cairns along
the Gulf Developmental Road. The nearest (small) town is Mount Surprise.
I have seen it implied that entry to the park can only be with an accredited guide, and that such a guide can only be provided by the company which runs the accommodation complex just outside the park. This is not true, and most of the park is readily accessible, though it is the case that the tubes themselves can only be entered with such a guide. These guides (look for the Savannah Guides signs) are also available elsewhere, eg Mount Surprise caravan park. In my experience these guides are very good, though of course there is variation, and it depends too on what your needs and expectations are.

Enough! Let's get into the tubes, and one thing that strikes is their size - they are enormous.
I don't normally include people in these photos, but it's really the only way to get the scale.
They are also very colourful and beautiful, though I'm of no help in interpreting the basis of these patterns I'm afraid. Hopefully you can just enjoy them with me.
The Mikoshi Tunnel.

The Dome.
Lava flow against the older granite, Mikoshi Tube.
In the quiet and dark of the tubes (in the longer ones you can be out of sight of the entrance and exit)
the appearance of tree roots is a reminder of the world outside.

Even up there though, the tunnels have a profound influence. Where they have collapsed, the gullies accumulate water in the Wet; even the ground above the tunnel roofs - which are largely impervious - retains water from the rains. Here, in the broader woodland landscape, vine forests grow, and their greener foliage seen from a vantage point traces the route of the tunnels across the landscape.
View from Kalkarni Crater rim; the green line of vine forest following the tunnel
can clearly be seen across the middle of the photo.
Vine forest - often called vine scrub or monsoon forest in Australia, and tropical dry forest elsewhere - is a form of rainforest which grows where the tropical summer rains are followed by a long dry season. They are lower, with a more open canopy, than other tropical rainforests, but retain the vines and epiphytes typical of 'true' rainforests where it rains all year round.

At Undara they are at their lushest in the drainage lines where the tunnels have collapsed, so are encountered as we enter and leave the tubes.
Vine forest growing outside the entrances to The Arch, above and below.

Vine forest seen from Mikoshi Tunnel.
The vine forests are not restricted to the depressions, though they are generally found in their vicinity.
Typical vine scrub, with the most prominent trees being Broad-leaved Bottle Tree Brachychiton australis,Family Malvaceae (formerly Sterculiaceae). They are deciduous, dropping their leaves in the dry to
conserve water; the vine forests as a whole are regarded as 'semi-deciduous'.
Near the tubes the lava spills across the ground, and vegetation has forced its way up through it.
Surface lava, above and below.

Inevitably too, lava appears on the surface around the numerous vents and craters, including Kalkarni Crater.
View into the extensive woodlands from Kalkarni Crater rim walk, with lava in the foreground.
Elsewhere the older granites make their presence felt in the woodland landscape.

Granite tors in tropical woodland, Undara.
These woodlands are magnificent, but they probably tend to be relegated to a 'background scenery' role here not least because they form such a dominant part of the northern Australian landscapes. I always revel in being in them.
Undara tropical woodland.
And with that I think we'll pause, and resume next time by meeting some of the plants and animals of Undara Volcanic National Park. I hope you can wait that long before rushing off to see it for yourself; sooner or later you really must do that though.

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Thursday, 21 September 2017

On This Day, 21 September: Lake Burley Griffin was born

Well, one could very justifiably argue that any number of other dates could fit that description of course, but I've opted for the day in 1963 that the weir gates closed on Scrivener Dam and the lake which is the centrepiece of Canberra, Australia's capital city, began to fill. As it happened that was a drought year and flow in the Molonglo River was minimal, so it took until the following March for the desired water level to be achieved. 
View from Black Mountain (part of Canberra Nature Park) across Lake Burley Griffin to the Federal Parliament.
The lake was named after Walter Burley Griffin, the US landscape architect who, with his wife
Marion Mahony Griffin, produced the grand design that won the international competition
to determine the shape and nature of the city, including the lake. However his surname was just Griffin,
never Burley Griffin, and many people have questioned the odd choice of name for the lake
- aside from the fact that his co-worker Marion was thus written out of history.

The city centre and the national institutions are all built on or near the shores of the lake, which have hitherto (mostly) been kept clear for public use. 
The view slightly to the left of the previous picture. The arrows represent (somewhat crudely) the city centre (Civic)
in brown, the Carillon in red, the National Library (and behind it the National Science Centre, National Gallery and
National Portrait Gallery and High Court) in green, the National Museum in blue and parliament again, in purple.
It is a substantial body of water 11km long and over a kilometre wide, and an average of four metres deep. Theoretically power boats are banned to retain the peaceful nature of the water body, but permits to avoid this restriction seem to be available for a range of purposes. On the whole however it is a calm and beautiful focal point, and is a haven for wildlife. The rest of this post will be a simple celebration of some of that wildlife; much of it comprises common birds, including of course many waterbirds, but even common birds are very welcome in the heart of a city! Fish in the lake - mostly carp, sadly - support a good population of four species of cormorants, plus darters and pelicans.
Little Black Cormorant Phalacrocorax sulcirostris drying its wings.
Cormorants don't have oiled feathers (which would inhibit their diving) so must
hang them out to dry at the end of a fishing expedition.

Little Pied Cormorant Microcarbo melanoleucos.One of the world's smallest cormorants, this species is familiar throughout Australia, north
into Indonesia and across the Tasman Sea in New Zealand.

Great Cormorants Phalacrocorax carbo are found on every unfrozen continent except South America,
though it is possible that more than one species is involved.

Male Australian Darter Anhinga novaehollandiae preening; he is collecting oil from
his uropygial gland at the base of his spine to distribute through his plumage.
It is common to see such birds on the edge of the paths along the lake shore, as here.
Australian Wood Duck pair Chenonetta jubata, female on the left.
A common grazing duck of uncertain relationships.
Black Swans Cygnus atratus are common on the lake, breeding in floating weed nests starting in winter.
Black Swan cygnet.
Land birds can be seen anywhere around the shores, but the woodland and forest remnants at the western end of the lake, especially near Yarramundi Reach, are especially productive, along with the Bulrush beds just off shore. 
Bulrush, Typha sp., Yarrumundi Reach; such stands support many shelter-loving small passerines,
as well as species of crake and even bitterns.
Australasian Reed Warblers Acrocephalus australis make the reed beds raucous with their metallic
territorial calls in spring and summer, going north to warmer parts of the continent in winter.
Superb Fairy-wren Malurus cyaneus male; one of the most familiar and 'popular' urban
birds of south-eastern Australia.
The Dusky Woodswallow Artamus cyanopterus is another migrant which is usually to be found
in spring and summer at Yarramundi Reach.
Even the open spaces can be rewarding however.
Welcome Swallows Hirundo neoxena.
Red-rumped Parrot pair Psephotus haematonotus feeding on exotic herb seeds.
It amazes me that even the brightly coloured males can escape the notice of passers-by
when feeding quietly in flocks alongside footpaths.
Water Rats Hydromys chrysogaster can often be seen in the daytime on the shore or swimming strongly,
especially in the vicinity of the Carillon.
By far the richest area of the lake however is found at the eastern end, near where the Molonglo and Jerrabomberra Creek both flow into the lake. Jerrabomberra Wetlands are protected as part of Canberra Nature Park. Large areas are reserved for research and refuge, based around the palaeochannels of the Molonglo, but the area around Kellys Swamp is one of my favourite local birding and general natural history sites around here. Over the years I've seen over 140 species here. 
Kellys Swamp in the evening. This is an ephemeral pan which these days is kept inundated from
Jerrabomberra Creek in all but the driest seasons.
Here is a small selection of some of my favourite memories there in the decade or so since I 'went digital'. 
Glossy Ibis Plegadis falcinellus, an uncommon visitor to our part of the world.
Great Egret Ardea alba alighting; a common visitor, but I liked this moment
(unfortunate shadow notwithstanding!).
Royal Spoonbill Platalea regia, in full breeding glory.

Yellow-billed Spoonbills Platalea flavipes are much less common visitors to Jerrabomberra.
Latham's Snipe Gallinago hardwickii visits every year from its breeding grounds in northern Japan.
I love it that I can watch this bird from a hide, while in the distance I can see Parliament House,
where the international treaties designed to protect the bird were ratified.
Australian Painted Snipe Rostratula australis; these birds created a major stir when they appeared and
stayed for a while in 2011. They are one of the rarest and hardest-to-see Australian birds,
numbering at the most a very few thousands.
Black-backed Bittern Ixobrychus dubius lurking among the bulrushes.
Another very hard to see bird, but not because of its rarity.
Australian Spotted Crake Porzana fluminea; when low water levels expose the mud, crakes and other
normally elusive rails appear. Always exciting times!
Freckled Duck Stictonetta naevosa, another threatened species which turns up
not infrequently at Jerrabomberra.
The now mature plantings around the swamp also attract an array of locally uncommon species, including these two honeyeaters which are not often recorded in Canberra.
Yellow-plumed Honeyeater Lichenostomus melanops.
Fuscous Honeyeater Ptilotula fusca harvesting honeydew.
While the birds tend to be the main attraction - and I could have selected many more! - they are not the only ones.
Brush-tailed Possum Trichosurus vulpeculus and joey, which took up residence in one of the hides for a while.
Chequered Copper Lucia limbaria.
Fiddler Beetle Eupoecila australasiae on Bursaria spinosa.
Every time I spend time by Lake Burley Griffin I am grateful to the Griffins for having had the vision, and to those who carried the vision through to the reality, decades after their deaths.

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