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, 27 April 2017

Litchfield National Park; sandstone and waterfalls

It's often said, perhaps especially in the backpacking tourism industry, both that Litchfield is "a poor person's Kakadu" and "better value than Kakadu" (Kakadu is of course the extraordinary and vast park of floodplains, woodland and sandstone escarpment east of Darwin in the Top End of Australia's Northern Territory.) This refers to the facts that Litchfield is closer to Darwin so can at a pinch be visited as a day trip, and the entrance rates are cheaper, presumably both of which are attractive to travellers having to watch both their time and money (or perhaps just preferring to spend both in other ways). It does share habitat similarities, but it is definitely not just 'mini-Kakadu'. 
Sandstone in tropical woodland, 'Lost City' (of which there are a few in Australia...).

Florence Falls.

Approximate location of Litchfield NP, 100k south-west of Darwin.
The park was declared in 1986, from pastoral leases. Its centre-piece is  a sandstone plateau supporting woodlands which account for the major part of the park's 150,000 hectares (not a small park by any means, though dwarfed by Kakadu's two million hectares). The 'lost city' is a focus of this part of the park, for good reason, though it is only accessible by four-wheel drive.
'Lost City' outcrops.
Sandstone however is prevalent throughout; here's another striking structure.
The woodlands have a grassy understorey, which sometimes extends as areas of pure grassland, which inevitably support a huge termite population.

Magnetic termite mounds, though we now know this is a misnomer.
While these flattened mounds certainly are all oriented north-south, it's not to do with
the earth's magnetic field, but with the sun. The narrow side faces the sun in the hottest part of the day.

Magnetic termite mounds, built by Amitermes meridionalis, from end-on.
These plains tend to be inundated in the wet season, when it's also hottest, so the residents
can't hide from the heat by retreating underground; they must instead manage the temperature above ground.

The equally huge 'cathedral mounds' are built by another species,
Nasutitermes triodiae
(ie 'spinifex termite with nose'!).
On the stony slopes shrubs grow more profusely in the woodland understorey; the restricted-range cycad Cycas calcicola can be a prominent element.
As the name calcicola suggests, this cycad does live on limestone, but only near Katherine;
in the other part of its range, in Litchfield, it is found on sandstone.
There are of course other habitat types present, including monsoon, or vine, forests. These are 'dry rainforests', which grow where there is an intense wet season followed by a very dry season; in Australia true rainforests, with rain all year round, only grow on the east coast. 
Litchfield monsoon forest; palms (especially this Livistona benthami) are prevalent.
This habitat usually grows in strips along stream lines.
I am often surprised at how sharp is the division between the monsoon forest and the adjacent woodlands; I expect nature to be more nuanced than this, but it seems to be the pattern in this part of the world.
Ecotone (transition zone) between Litchfield monsoon forest and woodland.
In some areas, especially at the base of the plateau, low-lying areas support paperbark swamps.
The dominant species in these wetlands is Weeping Paperbark Melaleuca leucodendra.
As the watercourses tumble off the plateau they give rise to the waterfalls which are so popular with visitors, both aesthetically and because of the 'plunge pools' which offer safe swimming at least in the dry season - in the wet crocodiles are known to make their way across country and take up residence. They are removed and relocated somewhere more appropriate (from our point of view at least).

Tjaetaba Falls

Tjaynera Falls.

Tolmer Falls.

Wangi Falls.

Florence Falls plunge pool.
I hope you can agree that this is an impressive and attractive collection of falls! However there is of course plenty of plant and animal life to enjoy too, though the park draws a lot of visitors in the dry, and larger animals sometimes keep their distance from the hubbub. Perhaps a modest parade of some of these species will do to wind up this introduction.

'Screwpalm' Pandanus spiralis; not a palm of course, but a lily relation, and found right across northern Australia.

The beautiful flower of Wild Gardenia G. megasperma.

Wild Gardenia tree; this member of the coffee family (Rubiaceae) is found
across the Top End and into Western Australia.
Gomphrena canescens, family Amaranthaceae, is found throughout the dry north-west of Australia.
Kapok Bush Cochlospermum bixaceae; another widespread tree of the western Top End and Kimberley.
Buchnera linearis, a herb found right across tropical Australia.
Formerly in Scrophulariaceae, now placed in the broomrape family, Orobanchaceae.
Tropical Banksia B. dentata is one of only three entirely tropical banksias, and
the only one to have left Australia - it is also found in New Guinea.

Hibiscus leptocladus, an attractive low-growing shrub.
Osbeckia australiana, family Melastomaceae.
Red-flowered Kurrajong Brachychiton paradoxum; the flowers grow on short stalks from the old leaf axils.
And (almost) lastly a widespread but very beautifully-flowering eucalypt.
Darwin Woollybutt E. miniata often dominates the woodlands.
My last plant offering today is a request for assistance; any idea what this one is?
Thanks in anticipation!
Let's end with some animals...
Yellow-sided Two-lined Dragon Diporiphora magna
Painted Grasshawk Neurothemis stigmatizans.
Dragonflies are abundant in the tropics, but life isn't always easy for them.
Green Emperor Anax gibbosus, a magnificent animal, and probably a magnificent lunch for this spider.
St Andrew's Cross Spider Argiope sp.; possibly the nemesis of the dragonfly above.
It's not just spiders though.
Dragonfly corpse being dismembered by Green Tree Ants.
Green Tree Ants Oecophylla smaragdina are an integral part of the Australian tropics - and elsewhere in south-east
Asia to India, though only in Australia do they have the green abdomen;
this might however just mean more taxonomic work to be done.
For more on these fascinating animals see here.
Two water striders, bugs of the family Gerridae, mating on the water surface.
And my sincere thanks to Craig (below) for pointing out my original embarrassing misidentification!
And there we might leave it, but I hope I've planted the seed of an idea for you. If you're in the area - and winter is coming to southern Australia, so why wouldn't you be?! - please see it for yourself. And remember that you really don't, and shouldn't, have to decide between Kakadu and Litchfield. You need to see both!

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Thursday, 20 April 2017

Palms; old and successful. Part 2

This posting forms the conclusion of last week's post on palms; today I'm simply going to introduce some species from both Australia and elsewhere.

Alexandra Palms Archontophoenix alexandrae forming a swamp forest in Centennial Lakes, Cairns.
This is their normal habitat in the east Queensland tropics.
Climbing Palms Calamus sp., Atherton Tablelands, north Queensland.
The stems can be up to 200 metres long; they form no crown, but have leaves crowded along
the end part of the stem.

A climbing palm with the delicious name of Vicious Hairy Mary Calamus radicalis, north Queensland.
In addition to the spines on stems and leaf edges, it has savage spiny 'whips' of tendrils up to four metres
long that assist in climbing and will tangle horribly in clothes or skin.
Kentia Palm Howea forsteriana, Lord Howe Island.
This lovely palm is endemic to the tiny Pacific island, but has now spread around
the world as a cultivated plant. It was also the subject of one of my first ever blog postings,
nearly five years ago. There's a lot more information about it there.
Queensland Fan Palm Licuala ramsayi, Daintree NP, north Queensland.
Restricted to streamsides and boggy areas of lowland rainforest of far north Queensland.
Livistona is a genus of some 30 species scattered across southern Asia - Australia, and in north-east Africa.
Cabbage Palm Livistona australis in wet gully, Kioloa, south coast New South Wales.
The 'cabbage' refers to the growing tip which was cut out by settlers for food - this of course killed the tree
Less lethally the leaf fibres were woven into 'cabbage-tree' hats.
Sand Palms Livistona humilis in tropical woodland, Kakadu NP;
the species is endemic to the Top End of the Northern Territory.

Livistona benthami growing by Cooinda Lagoon, Kakadu NP, Northern Territory.
This is its typical habitat, here and in north Queensland and New Guinea.

Red Cabbage Palms Livistona mariae, Palm Valley, Central Australia.
This species lives in isolation along just two kilometres of creek, surrounded
by desert where it could not survive. More on it here.

Mataranka Palms Livistona rigida, Boodjamulla NP, north-west Queensland.
It has a disjunct distribution here and around Mataranka in the northern Territory.

Livistona victoriae, Gregory River NP, western Top End, above and below.
Only recently recognised as a species, described in 1988, and found only in the
Kimberley district of the Northern Territory and Western Australia.

Chilean Wine Palm Jubaea chilensis, La Campana NP, central Chile.
This species (shot here looking into the sun, of necessity!) is found only in a small
area north of Santiago. The wine is fermented from the sap.

While we're on that theme, this is an iLala palm Hyphaene coriacea in woodland east of Masindi, Uganda.
In South Africa I was told that iLala is from a Zulu word meaning 'lie down', for the
supposed effect of the wine brewed from it.
(Naturally it will have different names in other parts of its extensive range.)

Still in Africa, this is a Raffia Palm, Raphia sp., Bwindi Impenetrable National Park, western Uganda.
This has the longest leaves of any plant in the world - they can be over 20 metres long and three metres wide!
Mauritia carana, Tambopata Reserve, southern Peruvian Amazonia.
These big leaves are in high demand for roof thatching, for their longevity - they may not
need replacing for a decade.

The same species, I am almost sure, from Waqanki Lodge on the lower eastern slopes of the Andes
in northern Peru. This lovely lodge is on the outskirts of the busy town of Moyobamba, some of
which can just be seen in the top left of the photo.

Also in Tambopata, the distinctive prop stems of Walking Palms, Socratea sp.
Despite the attractiveness of the story that they allow the palm to perambulate to more desirable sites
by means of shedding roots on one side and growing more on the other, it has no basis in the real world.
I don't really blame guides who are loth to abandon such a good yarn however!
On the other hand nobody seems to have demonstrated a convincing alternative explanation for the structures either.
The genus was indeed named for the philosopher by German botanist Gustav Karsten, for no evident
reason other than his assumed admiration for Socrates.

I hope that this relatively brief foray into the world of palms has been of interest or enjoyment - or preferably both! They certainly deserve our admiration and attention.

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