About Me

My photo

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. For much of my life I have been 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. Recently I have eased back somewhat, but am still writing, teaching, doing some radio work and running overseas tours - as part of my fascination with our Gondwanan origins I've been running tours to South America for the past decade. 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.

Thursday, 20 July 2017

Tasmania's Dove Lake; an exquisite stroll

Say 'bushwalk' and 'Cradle Mountain-Lake St Clair National Park', and the response is likely to be something like "oh, the Overland Track!". This six to seven day walk from Cradle Mountain to Lake St Clair is truly among the world's great wild walks, but clearly it's not for everyone. There is however another great walk in the park, one of my favourite day walks in Australia, and one accessible to anyone of even moderate fitness and mobility. 
Looking across Dove Lake to Cradle Mountain.
The six-kilometre lake circuit mostly keeps us at lake level, with sections of boardwalk, so we can
concentrate on the magnificent scenery around us, rather than on our feet!
Much of the park is wilderness, so of course no roads, but Dove Lake at the end of the road is readily accessed by car; the carpark is not far past the excellent parks visitors' centre. 
The end of the arrow indicates Dove Lake - the mass of Cradle Mountain-Lake St Clair NP
to the south of it is evident (160,000 hectares), and is contiguous with the even larger
Franklin Gordon Wild Rivers and Southwest NPs.
Your chances of enjoying the views without the intervention of clouds at some stage are not high, but on our most recent visit we were lucky.

Cradle Mountain is the souvenir of one of the most significant events in Australia's story. Around 55 million years ago Antarctica began to 'unzip' from the southern margins of what is now Australia, starting from the west. As the rift opened, vast quantities of subterranean molten material flowed into it, including an estimated 5,000 cubic kilometres beneath Tasmania! The dolerites of Cradle Mountain derived from the final disintegration of Gondwana and the isolation of Australian.
A slightly misty view of the Cradle Mountain dolerite towers.
A more distant view of the rugged dolerites.
The lake itself is of much more recent origin, being gouged out of the landscape over the past couple of million years by glacial action; Tasmania has been affected much more dramatically than the mainland by the current cycle of glaciations.
Glacier Rock. While they are not as obvious as I'd like, the horizontal scores in the rock were gouged out
by glacial action as the valley was being formed.

The lake is hard to photograph as a whole from ground level, being some two kilometres long and about 600 metres wide at its widest point. Here are some perspectives of it from various vantage points around the walk. (And while it's true that the views were never hidden from us by cloud, neither was there a lot of sun in evidence.)
As you can see from these two photos, there are sections of the walk which climb onto
ridges, which provide excellent views.
The brown stain in the water is the result of tannins from vegetation, especially tea trees, Leptospermum spp.

A stand of flowering tea trees.
Perhaps the most striking habitat that we pass through is the extensive area of cool temperate rainforest, dominated (like most Tasmanian rainforest) by Myrtle Beech Nothofagus cunninghamii (though I've just learnt that some would now prefer to use the genus name Lophozonia). This is a relic straight from Gondwana, and is eerily reminiscent of such forests in Patagonia and New Zealand.
Entering the rainforest.
Myrtle Beech trunks.
Here the darker trunks belong to Sassafras Atherosperma moschatum Family Atherospermataceae.
This is, as you'd expect, another old Gondwanan, and is an important co-dominant in many of these forests.
Very old Sassafras trunk.
At the end of this post I'll share a couple more rainforest scenes from nearby walks in the park, but for now we'll stay with Dove Lake.

Another striking plant is the giant heath known locally as Pandanus (which name is more usually used for the family Pandanaceae, of warm climate lily-relations).
Pandanus Richea pandanifolia, Family Epacridacaeae (or Ericaceae as it is increasingly known,
at least for now), in the landscape along the track, above and below.


Pandanus really is imposing, and can be found in both rainforest and eucalypt forest.
Yet another significant group of Tasmanian endemics is that of the ancient pines, and a couple of them are evident along our route.
Pencil Pines Athrotaxis cupressoides, Family Cupressaceae, against Cradle Mountain.
Pencil Pine foliage.

Very old Pencil Pine, which has been there for centuries.
While the cypress family to which the Pencil Pine belongs is widespread, Family Podocarpaceae
is Gondwanan. Here are a couple of shots of Celerytop Pine Phyllocladus aspleniifolius along the way.

The Gondwanan pines will feature in a future post, but for now we'll move on to some other endemic plants.

Pink Mountain Berry Leptecophylla (Cyathodes) juniperina, Family Epacridaceae (or Ericaceae if you'd rather).
Baeckia gunniana, Family Myrtaceae.
This one is actually also found in the mainland mountains, but it was named for a Tasmanian,
landowner and naturalist Ronald Gunn who collected for von Mueller.


Another species named for Gunn is certainly an endemic; it is a beech which grows as a shrub, and which unlike the Myrtle Beech is deciduous. We were there in February however, so it was still in full leaf.
Deciduous Beech N. gunnii, above and below.

The concertina leaves are very characteristic.

The beautifully aromatic Lemon-scented Boronia B. citriodora, Family Rutaceae,
is also an endemic.
Another habitat which the track traverses is Button Grass plain, which covers large areas of south-western Tasmania in particular, where the ground is water-logged or low in nutrient. There isn't a lot along the track, but there is some.

Button Grass Gymnoschoenus sphaerocephalus - which is not a grass at all, but a sedge, Family Cyperaceae.

Button Grass flower.
Another very impressive sedge growing in these boggy areas is the aptly-named Cutting Grass (well, the 'grass' isn't appropriate of course) Gahnia grandis, which can grow to over three metres high.


Cutting Grass in flower.
Yes, I know it's not a plant, but this slime mould is too magnificent not to share!
As  mentioned earlier, there are a couple of other, shorter walks in the immediate vicinity: Weindorfer's Forest Walk is between Dove Lake and the entrance, while Pencil Pines Falls Walk is at the entrance station. Both are worth it for the beautiful rainforest alone.

Beech forest; Weindorfer's Forest above,
Pencil Pine Falls, below.

Leatherwood Eucryphia lucida, Pencil Pine Falls. The Family Eucryphiaceae is an ancient
Gondwanan one, with the genus also present in South America.

However it is probably best known as the origin of the magnificent and distinctive leatherwood honey!
We might as well finish with the Pencil Pine Falls themselves, a very pretty little cascade.

I can't imagine you visiting Tasmania without going to Dove Lake, but I hope this has given you extra incentive. However if it were me I'd be waiting until the end of winter...

BACK ON THURSDAY
(And remember that you can get a reminder when the next post appears by putting your email address in the Follow by Email box in the top right of this screen.)

Thursday, 13 July 2017

Bowerbirds; charismatic old Australians

Bowerbirds have long fascinated laypeople and scientists (not to mention the odd natural history blogger). Obviously enough the key focus has been on the remarkable behaviour which gave them their name - the males' extraordinarily complex display stage and performance - and I shall be taking up that theme here.
Great Bowerbird Chlamydera nuchalis at bower, Boodjamulla NP, Queensland.
Their very origin and nature has been long debated, but it seems the answer is more interesting, and perhaps surprising, than the position held until recently that they are very close to the birds of paradise. In fact they are not close at all to those other great displayers; there are three Australian super-families of the old Gondwanan passerines, and the bowerbirds belong to the oldest of them (Menuroidea), along with lyrebirds, scrubbirds and treecreepers. (Birds of paradise, in the super-family Corvoidea, are closest to the White-winged Chough and Apostlebird, monarch flycatchers, and crows and ravens.)

There are 20 species, 10 restricted to New Guinea, eight to Australia, and two shared. Most are tropical, suggesting that their origins lie there, though one has expanded well into the temperate south-east. Two in Australia are at home in semi-arid and even arid inland woodlands. All are primarily fruit-eaters, and most also eat leaves, unusually among birds (especially in Australia); invertebrates, and even frogs and small lizards are also widely taken, especially for feeding to chicks.

Building the bower is a huge undertaking. Firstly a platform is created, comprising a deep layer of sticks, into which curved sticks are inserted, facing inward to form an avenue. In a series of Great Bowerbird bowers in Queensland, between 1400 and 1800 substantial sticks were counted in the bower (not counting the platform). Decorations vary between species, but while the Satin Bowerbird of the east coast of Australia does use primarily blue items to reflect his own colour, others tend to use a range of paler objects.
Satin Bowerbird bower, Bomaderry Creek Regional Reserve, suburban Nowra.
Here the blue decorations are almost exclusively artificial - plastic straws above,
and milk bottle rings below. (Sadly the latter have proved fatal in some cases, getting caught around the bird's neck.)
In more natural situations I have seen blue feathers, flowers and berries, and more unusual
items (which are apparently highly sought) such as shed snake skins and bones.
The Great Bowerbird bower at Boodjamulla featured many stones, some bones, plastic,
green berries and beer can ring-pulls...
... while this one south of Darwin focussed almost entirely on big snail shells...

... and this one in the same area was captivated by green bottle glass.
This Western Bowerbird bower (note that unlike the previous species, this one is open at the top)
at the Olive Pink Botanic Gardens in Alice Springs, central Australia, had a more modest collection
of bones and white plastic...
.... while this one nearby was taken by the fruits of Quandong Santalum acuminatum.
Most species paint the inner walls of the bower with a 'brush' of bark, using charcoal and chewed-up leaves and fruits. The bower is aligned north-south to make the most of the light on the decorations.

In Australia all but one of the bower-builders construct these avenues; only the Golden Bowerbird of the ranges near Cairns in north Queensland belongs to the 'maypole bower' school of construction. In this group, sticks or orchid stems are piled up around a sapling, or pair of saplings, to two metres high, and decorated with lichens and white flowers and fruit.
Golden Bowerbird bower, Mount Elliott, north Queensland.
(Scan of old slide - sorry.)
There is a high level of aggressive competition between males, with constant theft of desirable decorations, and damage to the rival's bower, to put him out of the contest for a while. And it is a bitter contest, with the less successful males not mating at all. 

Some of the plainer species have a brilliant pink or lilac erectile crest, which is normally hidden in the plumage of the crown. 
Western Bowerbird Chlamydera guttata, Olive Pink Botanic Gardens in Alice Springs, central Australia.
This is the most arid-loving bowerbird, found in the central and western deserts.
It seems that the quality of the bower really is telling her something about the quality of its owner. Perhaps surprisingly, a study on Satin Bowerbirds found a high correlation between the quality of the bower (using four defined features) and his health with regard to external parasites, plus his size. They also found that a more intense body colour (measured by reflectance spectrometry) was a predictor of low internal parasite loads and healthy feather growth rate, as well as body size again.
Satin Bowerbird male, National Botanic Gardens, Canberra.
The display is frenetic and riveting. In the case of the Satin Bowerbird he goes into a trance-like frenzy of display, his violet eyes bulging, his necked arched and wings alternately flicking rapidly and held stiffly above his back. With a favoured item from the display platform in his beak, he lowers his bill and raises his tail, standing on tip toes, all the while buzzing and clicking more like a machine than a bird. After some time of this he suddenly goes quiet, stepping partly out of sight behind the walls of the bower, showing her just his head and the object. At this stage he often erupts into virtuosic mimicry of other birds.

There is a long apprenticeship to get to this level of panache. In the Satin Bowerbird, and others, it takes six years for a male to attain his adult plumage; until then he resembles the females, and builds scores of bowers, probably all of which will be destroyed by his peers and elders.
Female or immature male Satin Bowerbirds, Canberra.
Sixteen of the 20 species build a bower; the three more primitive catbirds do not do so, but form monogamous pairs for breeding. The Tooth-billed Bowerbird Scenopoeetes dentirostris of the Queensland Wet Tropics uses a cleared display area, but does not construct.
Spotted Catbird Ailuroedus maculosus, Millaa Millaa Falls, north Queensland.
This primitive rainforest bowerbird is one of the two bowerbird species found in both Australia and New Guinea.
The name comes from the hair-raising yowling calls, which can also sound disturbingly like
a human baby crying.
The bower-builders are exclusively polygynous, with a male attempting to lure as many females as possible by his bower and accompanying display. Should she be impressed she enters the bower or mounts the platform and mating takes place there. From then on she's on her own; she's already built her nest and all brooding and chick-raising is down to her. 

Let's just end with a few bowerbird portraits, including a couple I've not yet illustrated.
Great Bowerbird, Croydon, north Queensland.
There can be something slightly unsettling about the intensity of scrutiny applied by this bird,
the largest of the bowerbirds.
Green Catbird Ailuroedus crassirostris (in the rain), Bangalee, near Nowra, New South Wales.
This, the second Australian catbird, is found well to the south of the range of the tropical Spotted Catbird.
Spotted Bowerbird Chlamydera maculata, Bladensburg NP, central Queensland.
This beautifully patterned bird is one of the two inland species.
Western Bowerbirds, Olive Pink Botanic Gardens.
Once lumped with the Spotted Bowerbird, it is a more richly coloured bird and found to the west.
Bowerbirds, a special part of Australia.

BACK ON THURSDAY
(And remember that you can get a reminder when the next post appears by putting your email address in the Follow by Email box in the top right of this screen.)