Reconsidering Kangaroos #2

This post follows my most recent one, which introduced the kangaroo family and explored the 'main line' of kangaroos and wallabies, the ones with which we're most familiar.

But the family is much more diverse than that, and becomes more so if we also consider the two other closely related families. So where did they all come from? The oldest Australian marsupials we know about were small carnivores, some of which climbed into the trees and apparently began utilising the abundant fruit and even more abundant but hard to digest foliage. Our fossil record of this time is still fairly sketchy, but it is evident that at some stage (more than 35 million years ago, but we can't yet be more precise) one of these arboreal groups came down again and resumed a ground level existence. These little pioneers were the ancestors of modern kangaroos and wallabies - those that stayed aloft were the grand-parents of the various modern possum groups.

Around 35 million years ago the ancestral macropods ('big foot', the convenient name for kangaroos, wallabies and kin - see last week's post) diverged into two lines. The descendants of both are still with us, though one whole line now comprises just one little survivor - all of its relatives (11 that we so far know about) are familiar to us only as fossils. The Musky Rat Kangaroo Hypsiprymnodon moschatus lives only in the rainforests of the Queensland Wet Tropics, and gives us an idea of what the oldest macropods might have looked like. With the widespread loss of coastal rainforest, they are mostly now found in the highlands, such as the Atherton Tableland.

 Musky Rat Kangaroo, Lake Eacham, north Queensland. The sole living member of the ancient family Hypsiprymnodontidae, this little animal is still regarded as a macropod (along with the next family we'll
mention) because of its close shared ancestry with the actual family Macropodidae.
They are only about 23cm long, plus a bare 14cm tail.

It differs from other macropods in important ways though - and after all it has had 35 million years to become different! It is only active in the daytime, it primarily eats fruit, it has five hind toes, and bounds along on all fours, rather than hopping. They can readily be seen crossing tracks or roads in the rainforest, or foraging on the forest floor, but are rarely as obliging as this one was, seen from the verandah of our rainforest cabin on a recent trip. As well as fruit - which they bury, with seeds, across the forest floor, greatly assisting tree seed distribution - they snack on invertebrates and fungi.

The remaining macropod line split again about 23 million years ago, giving rise to the modern potoroos and bettongs, in addition to the 'main line' macropods. These are also small mammals, dwelling mostly in dense understorey, from rainforests to coastal heaths. They are well known as 'environmental engineers', moving huge quantities of forest soil in their search for underground 'truffles', fungal bodies associated with the roots of trees and crucial to forest health. There are four living bettongs and three potoroos, several of them in serious danger of extinction. I can't offer you my own photos of these (because I don't have any!), but here's what they look like - just an example of each.

Long-nosed Potoroo Potorous tridactylus, courtesy Australian Museum.
This species, from wetter near-coastal forests of south-eastern Australia, is the only one of
the three potoroo species which is not listed as Threatened. Potoroos superficially resemble bandicoots,
but are unrelated, and soon reveal their macropod connections when they hop!

Eastern Bettong Bettongia gaimardi, courtesy Mulligans Flat Woodland Sanctuary.
Once common in woodlands of south-eastern mainland Australia from Queensland to
South Australia, we had exterminated them by the 1920s. Fortunately they have survived
well in Tasmania, where Red Foxes have never established, and recently a population has been
established in a large fenced sanctuary at Mulligans Flat, a woodland nature reserve
on the northern edge of Canberra.

Of the other three bettong species, two are listed as Endangered, and the Boodie, whose range once covered more than 60% of the continent, is limited to a few islands off the west coast. Stories don't come much sadder.

Well, those are the two macropod families that are not the 'main stream' Macropodidae family that we introduced last time. Within that though are also several other groups of kangaroos and wallabies that we really should meet too.

We divide the family into two sub-families - on one side is just one species, the enigmatic Banded Hare-Wallaby, and on the other are all the other 60 or so species. 

Banded Hare-wallabies Lagostrophus fasciatus, from John Gould's superb
A monograph of the Macropodidæ, or family of kangaroos
(courtesy of the inestimable Biodiversity Heritage Library).

This fascinating animal - a link to the early origins of the kangaroo family - was once scattered across southern Australia from the west coast to Victoria and south-west New South Wales. It too now only survives on a couple of western islands.

For the rest there are tree kangaroos, pademelons, rock wallabies, nail-tail wallabies, hare wallabies, the New Guinea dorscopsis wallabies and a couple of 'outlying' species (Swamp Wallaby and Quokka). I will briefly introduce them all; hope you can bear with me!

The ancestral tree kangaroo seemingly had second thoughts about its forebears' decision to come down out of the trees, and has again adopted an arboreal lifestyle. They are most closely related to the rock-wallabies, and it is not too hard to imagine such accomplished climbers adapting their rock-climbing skills to scaling trees to harvest the vast crop of rainforest leaves; most tree kangaroos are from New Guinea, and it is proposed that they arose there. This may have been a relatively recent move as they are not especially adept, but they can move on two legs or four along branches, and leap between trees or down to the ground from high in the canopy. Their forelegs are relatively much longer and more muscular than those of other kangaroos, and their feet are broader and with a grainy sole, like those of rock-wallabies. 

Lumholtz's Tree Kangaroo Dendrolagus lumholtzi, Malanda, Atherton Tablelands.
This plateau inland from Cairns in north Queensland is the centre of the remaining range of this,
the smaller of Australia's two tree kangaroo species. The name commemorates Norwegian explorer
and anthropologist Carl Lumholtz who introduced a specimen to science in the 1880s.

Bennett's Tree Kangaroo D. bennettianus lives further north on Cape York Peninsula, and there are about a dozen species in New Guinea, though more are being described and this number will rise - sadly, many of them are in serious trouble from over-hunting and forest clearing.

I discussed the wonderful rock-wallabies a while ago here, so won't reiterate the whole story, but in summary they seem to be closest to the rainforest and dense near-coastal shrubland pademelons (and the tree kangaroos) and have spread across the continent, specialising in cliffs and ranges, where their proficiency on sheer slopes is remarkable. Isolated now by predators (especially foxes and dingoes) and habitat loss, several species are in trouble. Key adaptations are short broad feet with rough soles like sandshoes and no protruding toe and claw, and a heavy non-tapered flexible tail to provide balance at speed. The following two photos show these characters, plus the colourful coats of some rock wallaby species, compared with those of most other macropods.

Black-footed (or Black-flanked) Rock-wallaby Petrogale lateralis, Alice Springs.

Yellow-footed Rock-wallaby, Flinders Ranges, South Australia. This is one of the oldest rock wallaby species,
though the group seems to have only diverged in the last few million years.

Black-footed Rock-wallabies on alert, Alice Springs Telegraph Station.

Pademelons comprise seven species of the genus Thylogale, small solid kangaroos of dense understories of rainforests and wet eucalypt forests (and sometimes coastal heaths). The name is an adaptation of the Indigenous name for them in the Sydney area. Colonial Botanist Richard Cunningham in 1827 used the form paddymalla (and went on to claim that it typically weighed 60 pounds!), and the obviously Anglicised paddymelon has also often been used (though we tend to use that more for various native and exotic species of 'cucumber').

I can show you all three Australian species, though it's not very hard to do as while they have suffered from habitat loss, they can still be quite common and even numerous where they persist, though they tend to be nocturnal and wary and rarely stray far from shelter.

Red-necked Pademelon Thylogale thetis, Mt Clunie, near Kyogle in inland far northern New South Wales.
These emerged to feed at the same time every day, as is typical of the species, which lives along the
sub-tropical east coast.

Tasmanian Pademelons T. billardierii, Narawntapu NP (formerly Asbestos Range), northern Tasmania.
Despite the name, this one used to live in mainland south-eastern Australia too; it has gone from there since
European settlement, but is common throughout Tasmania.
Like other pademelons the tail just drags behind, and is not used for support.

Red-legged Pademelon T. stigmatica, Kingfisher Park, Julatten, north Queensland.
This youngster probably shouldn't have been out on its own. This tropical species is found along
the east coast from north of Sydney to Cape York and into New Guinea, where there are
also another four species.

There are - or were - three species of nailtail wallaby, genus Onychogalea, small wallabies characterised by a  hard spur at the tail-tip, for no apparent purpose. Another characteristic is their gait - at speed a nailtail holds its arms out forward and down for balance, seemingly rotating, hence the old name of Organ Grinder. The Northern Nailtail Wallaby O. unguifera is still doing OK across northern Australia, but another one is Endangered and the other was very rare by the early years of the 20th century and extinct within a few decades - both had huge ranges across drier Australia.

Poignant portrait of Crescent Nailtail Wallabies O, lunata From John Gould's mighty Mammals of Australia, 1863.
At time they were common and widespread and remained so until the 20th century. Thereafter records rapidly
declined; the last substantiated records were in the 1930s.

The story of the Hare-wallabies, genus Lagorchestes, is sadly similar - four species, covering most of the continent in the 19th century, now only two and one of those has seen its range shrink from most of the central and western deserts to two small islands off Western Australia. This one, the Rufous Hare-wallaby L. hirsutus, remains a key story animal to many desert people and there have been determined attempts to reintroduce it to the central deserts; so far these attempts have been thwarted by cats and foxes, but there are good captive populations and hopes remain. (The hare-wallabies incidentally don't include the Banded Hare-wallaby that we discussed earlier! That was a case of mistaken identity, but the name stuck.)

Spectacled Hare-wallaby L. conspicillatus, also from Gould's Mammals of Australia.Only this species of the three is still widespread across the tropical grasslands, though even here there
are worrying signs of decline in some areas.

The Dorcopsis wallabies (genera Dorcopsis and Dorcopsulus) are rainforest dwellers of New Guinea and nearby Indonesia; I recall some in Adelaide Zoo around the 1970s but I don't think that there are any in Australia now.

White-striped Dorcopsis D. hageni, courtesy A to Z Animals. It is found across northern New Guinea,
though I'm sure this a captive animal. I recall this strange 'tripod' stance using the stiffly bent tail from
the Adelaide Zoo animals, though they were Grey Dorcopsis D. luctuosa.

Which brings us to the two 'loners', each quite familiar to most Australians with an interest in wildlife, the only members of their respective genera and with no close relations.

The Swamp Wallaby Wallabia bicolor is common and widespread along the entire east and south-east coast and hinterland; indeed it was apparently to this species that the Sydney language name of  'wallaby' (or something similar) was applied and adopted by Europeans for all the familiar smaller kangaroos. The names Black and Black-tailed Wallaby have also been used - and arguably more helpfully, though I have also read that the Swamp name refers to the rank smell and taste of the meat. The black tail, relatively small head and odd gait - hump-backed with head held low and tail stiffly out behind - immediately mark the Swampy as 'different' from other wallabies.

Swamp Wallaby, Mulligans Flat Nature Reserve, north Canberra. This is an attractive, colourful species.
It is more of a browser than grazer; this one is munching on a benign mistletoe leaf from a low-hanging clump,
but they are also seemingly immune to toxic fare such as Bracken Fern (poisonous to stock) and introduced Hemlock -
if only poor Socrates could have learnt that trick.

Lastly, and far from least, the Quokka, Setonix brachyurus, the favourite of many Australians, though they are only found in Western Australia, and only likely to be seen on Rottnest Island, off the coast of Fremantle, Perth's port. This was the second Australian marsupial to come to the attention of European explorers when Dutch navigator Samuel Volckerzoon reported 'wild cats' on an unidentified island near Perth in 1658. The poor Quokkas had to get used to being misrepresented, as later Willem de Vlamingh characterised them as 'a kind of rat big as a common cat'. Indeed he named their island Rottnest - ie Rat's Nest. They were common along the coastal plain but while still there they are scarce and not often seen; on Rottnest however they are completely accustomed to people.

Quokka, Rottnest Island. The round face, shaggy body and short tail make this engaging little
animal quite unmistakable.

So, a fairly extensive survey-cum-tribute to one of the most fascinating groups of mammals in the world, though most of us don't know much about most of them, and we've overall treated them very badly. We should never ignore them though, and I'd love to think I might have encouraged you to look more closely - and seek out more of them. Marvellous macropods. Thanks for coming with me.

NEXT POSTING THURSDAY 14 MARCH
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