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I've been a Canberran since moving here from Adelaide on the first day of 1980. I now live in suburban Duffy with my partner Louise Maher, ABC 666 radio and on-line journalist. Among my early memories is following Sleepy Lizards (Shinglebacks) around the paddocks north of Adelaide, guarded by the faithful bull terrier. I have always been passionate about the natural world, trying to understand how it works, how the nature of Australia came to be, and sharing those understandings. My especial passions are birds, orchids and mammals. I am now a full-time naturalist, running bush tours, writing books etc, doing consultancies, presenting a regular radio slot on local ABC, chairing a government environment advisory committee and running adult education classes. I was awarded the Australian Plants Society Award in 2001 and the Australian Natural History Medallion in 2006, both for services to education and conservation. As part of my fascination with our Gondwanan origins I've been running tours to South America for the past few years.

Wednesday, 15 April 2015

Have you seen a Casuarina?

This is the latest in an irregular series on some of my favourite trees, of which there is no shortage. The most recent instalment was here, from where you can follow back if you wish.

Sound doesn't usually feature heavily in talking about plants, but casuarinas are different. The inside of a grove of casuarinas whispers; it's like standing surrounded by aeolian harps. 
Belah Casuarina pauper, Gawler Ranges NP, South Australia.
Belah forms woodlands across dry inland Australia; it used to be known as C. cristata,but the species has been split into two, with cristata found from central Queensland
to central western New South Wales.
The reason for the whispering lies in the foliage, which superficially resembles pine needles; indeed people often mistake them for pines. These 'needles' however are branchlets; look closely and you'll see that each branchlet (or cladode technically, for branches which perform a plant's photosynthetic function) is ringed with tiny teeth. These teeth are the remnants of the leaves, presumably reduced to contain water loss in their often arid environment.
Belah cladodes and leaflets, White Dam Conservation Park, South Australia.
If you enlarge the photo the rings of leaflets are quite obvious.
Australia though is only relatively recently a dry continent, so where did drought-resistant casuarinas come from? I think the answer to that lies in their distribution; while Australia is their stronghold, with some 70 of the roughly 100 species, they are found throughout the western Pacific. Seashores are one of the most ferociously droughted habitats, irrespective of rainfall - plants must effectively compete with soil salt for water. (This is a bit crude, but it'll do for our current requirements.) A plant like a casuarina which evolved on the shore would be pre-adapted to living in the dry inland as the country dried out. 
Belah and Bluebush Maireana sedifolia, White Dam Conservation Park, South Australia.
I think this one is interesting because bluebush is a member of the huge saltbush family Chenopodiaceae,
which I suspect also evolved in coastal environments, where some species are still found.
Some species of course have never left the shores. Horsetail Casuarina (or Sheoak - we'll come back to that name in a while) Casuarina equisitefolia is found on beaches from south-east Asia to north-eastern Australia.
Horsetail Casuarina (and male Great Frigatebird!), Lady Elliot Island, Queensland.
Swamp Oak Casuarina glauca, Cullendulla Nature Reserve, New South Wales.
Here it forms an interface with the mangroves on the right; while the mangroves
are flooded with seawater twice daily, the casuarinas are only inundated at very high tides.
They cope with it perfectly well though.
This one has become a serious invasive weed in the Florida Everglades.

We can get a hint from the previous picture (the Horsetail Casuarina) too as to why the great Linnaeus used the name Casuarina when he based the genus on this species; he thought the foliage resembled the hairy-looking plumage of the Cassowary! Personally I think he worked too many late nights...

In the late 1980s the late and highly respected Lawrie Johnson of the Royal Botanic Gardens, Sydney, split the hitherto single genus Casuarina into four; two of those genera are relatively small and barely represented in Australia (by one very restricted tropical Queensland species) but Allocasuarina, distinguished most obviously by larger and knobbier fruits, now represents more than half of what were previously Casuarina. Not everyone is happy with this change, but most authorities go along with it. I use 'casuarina' in lower case as a group name for the family.

I mentioned that casuarinas are quite pine-like at first glance, but they are legitimate flowering plants. As they are wind-pollinated however the flowers are fairly inconspicuous. Moreover most species have separate male and female plants (that is, they are dioecious); the rest have separate male and female flowers on the one plants (monoecious).
Scrub Sheoak Allocasuaria distyla female flowers and cones, Morton NP, New South Wales.
Black Sheoak A. littoralis male flowers Nowra, New South Wales.
The name sheoak is of vexed origin. It is widely supposed to be an indication that the timber was regarded by early British settlers here as of inferior quality to that of European oak, but I'm not at all convinced. I believe it is one of the many names of indigenous origin which later became anglicised as the origin was forgotten, and a new back-filling origin created. I have several bases for this belief, all of them of course circumstantial (as is the traditional explanation). For one thing the wood was actually valued quite highly. The Sydney Gazette of 1803 reported that "This wood is allowed to rank in Europe with the mahogany of Jamaica." That wood was very highly prized for furniture in particular. There is some beautiful casuarina ('beef wood') furniture in the National Museum. I point too to the occasionally encountered form shiock, and the existence of the name buloke for some inland species (notably C. luehmanii) - surely too much of a coincidence? Moreover the term he-oak is also found, though there is no suggestion the timber of these species is superior. And I find convincing the evidence of Richard Howitt, who in his book Impressions of Australia Felix in 1845 wrote quite explicitly "Shiac is the native name - vulgarised to she-oak". 

I don't doubt that some readers will be quite sure I'm wrong - and they may be right, though I think we can agree that we'll never be entirely certain.

To wrap up, here are some more casuarinas, which I hope you can enjoy as much as I do.
Desert Oak Allocasuarina decaisneana at sunset, Uluru, central Australia.
More on this wonderful species here.
Allocasuarina huegliana Boyagin Rock, Western Australia.
Drooping Sheoak Allocasuarina verticillata, above and below.
Above, Rosedale, New South Wales.
Below, Freycinet NP, Tasmania.
River Oaks Casuarina cunninghamiana, Deua NP, New South Wales.
This species always grows along near-coastal stream lines, forming riverine forests.
Thanks for bearing with me; I hope you can enjoy a casuarina soon.


Wednesday, 8 April 2015

Kakadu in the Wet

A nasty early cold snap has hit Canberra, and we're thinking wistfully of the tropics. It's also been a wet cold snap, so I'm thinking most specifically of rain in the tropics, and it's only a few weeks since we were in the magnificent Kakadu National Park, in Arnhem Land in the 'Top End' of the Northern Territory. We got very wet there, but it was warm!
Kakadu National Park is indicated by the red arrow, a little east of Darwin
(we live way down in the south-east corner of the continent).
The Tropic of Capricorn is marked, running pretty much across the middle of the map.
January is definitely not tourist season in the Top End; while it's not especially hot - daytime maximum temperatures temperatures rarely vary beyond 32 to 34 degrees centigrade - humidity is usually close to 100% and it's standard for afternoon storms to roll in. But for a naturalist it's rich, the storms are magnificent, and of course there aren't many tourists...

Kakadu is one of the world's great parks, and at 20,000 square kilometres it's the largest national park in Australia (though some reserves in other categories are larger). Its significance has been recognised in its World Heritage Listing; it is one of only four places in Australia listed both for outstanding cultural and natural values. The Bininj Mungguy people and their ancestors have lived here for at least 50,000 years, making them the oldest living culture in the world. 
Burrunggui (more generally known, though incorrectly, as Nourlangie Rock) in woodlands, Kakadu NP.
This site was and is of huge importance to Bininj Mungguy people and contains many significant art sites.
Habitats include vast savannah woodlands, monsoon forest, sandstone escarpment country, coastal habitats and rivers and associated wetlands. Kakadu supports a quarter of Australia's land mammal species and freshwater fish species and more than a third of its bird species. 

Chestnut-quilled Rock-Pigeon Petrophassa rufipennis Burrunggui.
This beautiful sandstone specialist is pretty much restricted to Kakadu.
However a focus for us, in a too-brief visit, was the Cooinda (or Yellow Waters) Billabongs wetland complex, famous for its guided boat tours run by traditional owners (or often by biologist guides trained by them). We actually went out twice ('second time half price' or something, but we didn't need much persuasion), in the early morning and late afternoon. 

This was Gudjewg, the Monsoon Season, which roughly corresponds to January - March. (The Bininj Mungguy traditionally recognise six seasons, based on what nature is doing, and these have been pretty much adopted by whitefellas there too, where European-based concepts of seasons don't mean much!) From our point of view the upside of this was that the boats could leave the river channels and travel across the flood plains; the downside is that with water across the whole vast landscape, birds have scattered with it, and perhaps counter-intuitively the Wet isn't a great time for seeing waterbirds. (Much better near the end of the dry when they are concentrating on diminishing waterholes.)

However we can and will come back for the birds; the experience of gliding through flooded channels and over the plains was mesmerising (though it's not easy to tell where one stops and the other starts). Perhaps the pictures can tell their stories for a while now.
Home Billabong at dawn.

Channel, Cooinda.

Yellow Waters Billabong, where the channel opens out.
Yellow Waters Billabong.

Floodplain reflections, above and below;
in the photo above can be seen some infrastructure associated with a walking track used in The Dry.

While birds, and even crocodiles, which tend to lie under the overhanging vegetation when the water's high, aren't very evident, there are still interesting plants to enjoy - as well there might be, with over 2000 species known from the park.
River Pandanus Pandanus aquaticus, a species always found along streamlines.

Paperbarks Melaleuca spp., growing on the flood plain.

Water Lily Nymphaea violacea, found across northern Australia and in New Guinea.
This is a very important plant to local people, who eat roots, stems and seed heads, either raw or cooked.

Lotus Lily Nelumbo nucifera; also an important plant, for food and medicine, to the Bininj Mungguy.
Unlike the Water Lily however, this one is also found throughout much of Asia.

Native Bamboo Bambusa arnhemica; a Top End endemic and one of only three bamboos native to Australia.

Livistona benthamii, a palm found in the Top End, Queensland and New Guinea,
where it is always associated with waterways and flooding.

Freshwater Mangrove Barringtonia acutangula Family Lecythidaceae.
Found in seasonally flooded wetlands across northern Australia and into Asia.
Previous comments notwithstanding, there are always some birds to be seen.
The world's eight jacana species are always a delight;
the Comb-crested Jacana Irediparra gallinacea is Austalia's only species,
though it is also found in Indonesia and the Philippines.
Here is a view of the remarkably extended toes which are the key feature of the group
and which enable to them to famously walk on lily pads.
Eastern Great Egret Ardea modesta, in full magnificent breeding flush.
The sky was criss-crossed with skeins of Glossy Ibis Plegadis falcinellus (above and below)
more than I'd ever seen before in one place. I have no idea where they were going to or from though.

White-bellied Sea Eagle Haliaeetus leucogaster, found from India to Australia.
Always magnificent, this one was set off beautifully by the darkening storm clouds behind it.
By now, with sheet lightning blazing and thunder rumbling ever more loudly, it was
time to head for home; a small metal boat on water isn't the best place in such conditions.

Immediately after this photo was taken, it was definitely time to pack the camera away;
the boat had a canopy but the now torrential rain was coming in at 45 degrees.
Until then the front seats had seemed a very good place to be...
It was a great excursion nonetheless, and we'll remember it with both fondness and awe.

Tropics in the Wet? Yes please!


Thursday, 2 April 2015

Considering Kangaroos

I hear so many stories of people coming to Australia and expecting to see kangaroos in the main streets that I suspect that some of them must be true. And here in Canberra it's pretty close to the way things are! In suburbs near the numerous hill reserves which are scattered through the urban area it's common to see roos grazing the lawn or drinking from garden ponds in dry spells. And driving anywhere in Canberra can be potentially hazardous when the roos are on the move. I could meet you at the airport and pretty much guarantee to find you Eastern Grey Kangaroos within about 10 minutes. 
Eastern Grey Kangaroos Macropus giganteus, just a few minutes from my Canberra suburban home.
These animals are showing the classic kangaroo characteristics of powerful hind legs, short forelimbs with grasping paws and a long heavy counter-balancing tail. Lounging about stretched out on the ground is typical daytime behaviour too.

The long hind legs are an adaptation to hopping, a form of locomotion which seems to have arisen in the ancestral kangaroos at least 30 million years ago. While members of a few rodent families, and a member of one other family of small marsupials (the carnivorous Kultarr) have independently evolved hopping, the kangaroos are the only large vertebrates ever to have developed the trick. (Tales of hopping dinosaurs seem to be no more than tales.)
Eastern Grey Kangaroos on the move.
It's not an efficient mode of locomotion at low speeds; at less than 12km an hour a trotting dog for instance uses less energy. As speed increases however the hopping kangaroo begins to pull ahead energetically, and increases its relative efficiency further as its speed increases. At 22km per hour, the highest speed that I'm aware that energy expenditure has been measured, a hopping kangaroo uses less than 75% of the energy a similarly sized dog would. At speeds of 40kph - which a kangaroo can readily achieve - it would be expected to be twice as efficient. 

The reason for this has been tentatively suggested in terms of the muscles and tendons acting like springs, storing kinetic energy which is used in the next leap. Doubtless this occurs, but we now know that galloping animals also utilise this 'bouncing ball' strategy, so a roo's advantage can't be attributed solely to this. It seems that the explanation lies in the much longer stride a hopping kangaroo can achieve. An animal can increase speed either by taking longer strides, or by taking more steps or hops per minute; it is the latter which uses much more energy. A kangaroo's gait allows it to simply to take longer and longer hops as it accelerates, to more than four metres per bound. At very high speeds it will also start to put in extra hops, which presumably uses more energy.

At very low speeds however, such as when feeding, a kangaroo 'caterpillars' along, using five limbs, the tail being co-opted for this purpose. 

Red-necked Wallaby Macropus rufogriseus, Namadgi National Park near Canberra.
To get to the next patch of desirable grass, the animal swings its back legs forward together, while balancing
on its forelegs and tail.
(Curiously, when swimming, a kangaroo suddenly learns how to move its hind legs independently of each other, the only time it does so.)
Now you've probably been distracted because I've suddenly switched to talking about a wallaby! Let's get that one out of the way. In vernacular, we tend to use 'kangaroo' for the larger members of the family Macropodidae (which has some 60 members), and 'wallaby' for smaller ones, but it's not taxonomically meaningful. It's even less so for today's purpose, as I'm going to be talking about only the members of one genus, Macropus (ie 'big foot'). I use 'kangaroo' loosely to refer any member of the family, but better still is the word macropod, which I'll use from now on. 

It was only by accident - literally - that we use the word kangaroo, that being the name for Eastern Grey Kangaroo in the Guugu Yimithirr language of north Queensland. It came to our attention very early on in the history of British involvement with eastern Australia, when James Cook's Endeavour struck a reef in 1770 near where Cooktown now stands, necessitating an extended stay, during which naturalist Joseph Banks learnt the word for the animal his greyhounds caught. I like to muse that had Cook sailed on by, as he'd intended, we'd almost certainly be calling them something like Patagarang or Badagarang, that being the word in the language of the people who lived in the area where the first settlement intruded on them, in 1788 where Sydney now stands. 'Wallaby' also comes from the language of the Sydney people (often referred to as Dharug, though that seems open to considerable doubt), apparently being the word for what we call Black-tailed or Swamp Wallaby Wallabia bicolor. 

And to head off another oft-asked question, 'Wallaroo' is not a kangaroo-wallaby hybrid, but any of three species of mostly stocky muscular hill kangaroos. This is yet another Sydney language word. This term is used for M. robustus along the Great Dividing Range along the east coast, while the word Euro (from the Adnyamadhanha language of the Flinders Ranges in South Australia) is used throughout the inland for the same species.

As marsupials, embryos develop externally, but in the pouch (ie the marsupium). In the case of the big kangaroos time in the pouch varies with species from 200 to 300 days.

Agile Wallaby Macropus agilis with joey, Cape Hillsborough NP, tropical Queensland.
This one is starting to explore the world, but retreats to safety when it feels the need.
Eastern Grey Kangaroo, Canberra. The joey dives in head-first, then reorganises itself while inside.
More seasonal climate species, such as the Eastern and Western Grey Kangaroos M. fuliginosus, breed seasonally, but the extended pouch life means that the female is usually caring for a pouch young and a still dependent joey 'at foot', who follows her around and feeds from her. Arid land species, such as Red Kangaroos and Euros, tend to breed continuously. In either case the female produces quite different types of milk from the two teats (protected in the pouch), with one of them elongated to assist the youngster leaning in from outside to feed. Furthermore Red Kangaroo females will at any one time be not only caring for a pouch young and dependent joey, but will also be carrying a blastocyst (an embryo 'frozen' in development at only a few cells, some 0.25mm in diameter). This is released to grow when either the mother loses the pouch young, or it leaves the pouch as it grows.

There is of course a lot more to say, but you've probably had enough for now. Let's finish with a partial gallery of Macropus, though I fear I can only offer you about half of the thirteeen species.

Big male Eastern Kangaroo, Canberra.
Like most of the big kangaroos (though not many smaller macropods), Eastern Greys have benefited
greatly from agriculture, which supplies pastures and water points. They are expanding well out of their
traditional range into the semi-arid zone, utilising farm dams.

Western Grey Kangaroos:
female, Cape Le Grande NP, Western Australia (above);
big male, Silverton, far western New South Wales, below.
Western Greys are really brown. They evolved in Western Australia when the south-west
was isolated from the east by arid conditions, and later spread east. It was only recognised
as a separate species from the Eastern Grey in recent decades.

Red Kangaroos M. rufus; Western Australia (above), south-west Queensland (below).
This beautiful animal is found throughout the arid inland.
Theoretically males are red and females blue-grey, but a substantial proportion of animals (varying
between populations) has the 'other' colour, or a blend.
Wallaroo, Nangar NP, New South Wales.
Wallaroos (mostly from the Great Dividing Range) are blue-grey, while Euros (from the drier inland)
are reddish grey, despite being the same species.
Note the shaggy coat and big ears.
Euros, Broken Hill, far western New South Wales (above)
and Idalia NP, south-western Queensland, (below).
Both habitats are typical, in rocky ranges.

Kangaroo cave painting, Nourlangie Rock, Kakadu National Park, Northern Territory.
In this sandstone habitat, the painting probably represents a Euro.
Antilopine Wallaroos (or Kangaroos) M. antilopinus, Kakadu NP.
This is the kangaroo of the tropical savannahs.
Agile Wallaby, Kakadu National Park.
Also a tropical macropod, though one that goes into the brushes more than the Antilopine does.

Red-necked Wallabies, Namadgi NP, near Canberra, above and below.

The origin of the species name, rufogriseus, 'red and grey', is obvious.
In Tasmania (here Ben Lomond NP) the same species is known as Bennett's Wallaby.
Tammar (or Dama) Wallaby M. eugenii, Kangaroo Island, South Australia.
This engaging little animal is still common here, but scarce on the adjacent mainland
and in south-western Western Australia.
I hope you've enjoyed this brief introduction to a genus that many of us here take for granted; in the not-too-distant future I'll talk about some of the other small macropods in other genera.