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Archive for the ‘Marsupials’ Category

Intelligent “dog with hands” versus primitive (and quite stupid) marsupial:

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Treed opossum, 1917

opossum treed 1917

This photo comes from Mammals of America by Harold Elmer Anthony. This book was published in 1917, so it unfortunately refers to the opossum hunter as a “Southern Darkey.”

Of course, African Americans living the South often hunted opossums for meat, and they relied upon good treeing dogs to assist them in their hunts.

This dog appears to be of a farm shepherd type, but just as often, they would rely upon their curs or feists to tree the marsupials, which they usually captured alive.   To get the opossum out of the tree, they would shake the tree to make it fall out.

The opossum would then be brought home in a burlap sack and then fed table scraps for several weeks to make the flesh taste better. Opossums are known carrion eaters, and it was commonly believed that the carrion diet tainted the meat.

After a few weeks of being fed table scraps,  they would slaughter the opossum.

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Eastern quolls

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The quoll of two colors

eastern quoll

Quolls are small marsupial carnivores that fill a niche somewhat similar to that of martens in the northern hemisphere.

They are dasyurids and are close relatives of the Tasmanian devil and the thylacine.

There are four species of quoll in Australia and two in New Guinea.

One of the Australian quolls is the Eastern quoll (Dasyurus viverrinus). It is currently found only in Tasmania, but its range once included much of the southeastern Australian mainland.

It comes in two distinct morphs.

A fawn:

fawn eastern quoll

And a black:

black eastern quoll

Now, remember when I said these animal were extinct on the Australian mainland?

Well, that’s not exactly accurate.

The last “native” mainland Eastern quoll died in Sydney in 1963. These little marsupials, though called “native cats,” are thought to have suffered greatly when foxes were introduced to Australia.  Foxes readily kill them, and because Tasmania has been fox free up until very recently. it was thought that this was why the Eastern quoll has been able to thrive there.

However, there appears to be a population of Eastern quolls living in the state of Victoria. Victoria is within the Eastern quoll’s historical range on the mainland.

These quolls are most likely not a relict population of native Victorian Eastern quolls.  They most likely are escapees from Mount Rothwell Conservation and Research Centre near Melbourne. These quolls are breeding in large enclosures at the facility, and it is possible that they get a few escapees every now and then.

But that’s what’s left of the Eastern quoll on the Australian mainland, but there do continue to be lots of sightings of them.

Maybe one day we’ll find a genuine relict population of Eastern quolls on the mainland.

I certainly hope so.

I don’t think the fox can ever be eliminated in Australia.

That genie was let out of the bottle long ago, and it can never be put back.

But fox and cat free areas can be created. Even encouraging dingo populations to expand might play an important role in controlling fox and cat numbers.  Dingoes will kill cats and foxes, and that could mean that the quolls and other small native fauna might thrive in dingo-rich habitats.

Australia’s native fauna was essentially doomed the second Europeans encountered the continent.

But parts of the doom can be mitigated.

I hope we can mitigate some of the issues have that have really harmed the quoll of two colors.

Such a bad fate shouldn’t befall such a ridiculously cute and undeniably fascinating animal.

 

 

 

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white thing

As most of you figured out this white creature is a white sugar glider (Petaurus breviceps).

It is a leucistic individual. Unlike albinos, leucistic animals still produce some pigment.

This white coloration would never serve it well in the wild. Something that white would attract virtually any owl that happened to pass through the area.

However, this white coloration does increase their value on the pet market.  This is a captive individual.

Sugar gliders are the most commonly available marsupial on the pet market, even if they do make a lot of noise at night (including some pretty loud buzzer shrieks) and can give a pretty nasty bite.

 

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Hell’s welcome committee

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Taxonomy joke

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Female mainland thylacines that were living during the Holocene (skull at far left) were much smaller than dingoes from the same time period (skull at far right). This size difference means that dingoes could be effective predators of female thylacines on the mainland and could have been a cause of their extinction.

Thylacines went extinct on the mainland of Australia before European colonization.

They were around on Tasmania up until the twentieth century.

After the Thylacoleo (“marsupial lion”) species became extinct some 40,000 to 50,000 years ago, the thylacines were the largest marsupial carnivores.

And the largest terrestrial predators in Australia. The saltwater crocodiles clearly had them licked, but outside of riparian and coastal areas and in the southern part of the continent, the thylacine was the top “dog.”

However, the reason why the thylacine disappeared from the mainland has been up to conjecture.

Several hypotheses have been propsed.  Almost all involve some discussion of the dingo’s arrival on the continent– a date that is not exactly clear in either the genetic or paleontology literature.

The initial hypothesis was that dingoes simply outcompeted thylacines. Dingoes hunted in packs, and what’s more, as variants of domestic dogs, they would have had a very close relationship with humans.

Pretty much every study about thylacines has made comparisons with those that were in Tasmania during historical times.

These thylacines weighed as much as 70 pounds, and because we have historical accounts a thylacin splitting the skulls of a bull terrier with its jaaws,  it assumes they would have been a match for even a pack of dingoes that included individuals that weighed 30 to 45 pounds. (There is, however, some recent recent research that suggest thylacines had structurally quite weak jaws, so they may not have been all that effective in a combat situation with a mid-sized dog).

However, this is a bit of an unfair comparison.

If one assumes that thylacines that on the mainland when dingoes arrived were exactly like the ones in Tasamania, then it becomes more difficult to see how dingoes could have dominated them. Only by allowing for the dingo’s advantages– such as its association with people, who were on the increase throughout the continent, and the dingo’s pack hunting behavior which allowed it access to wider variety of prey– can we see how a dingo would have dominated the thylacine on the mainland.

However,  a recent study was just published in PLoS One.  In this study, researchers examined the body and skull size thylacine and dingo remains from Nullarbor Plain and the southwestern part of Western Australia that were dated to the early Holocene.

The results revealed something amazing.

Dingoes of that time were quite a bit larger and heavier than mainland thylacine.  The researchers found:

The smallest thylacines were 19.2% and 28.2% smaller than the smallest dingoes in the Nullarbor and southwest, respectively. The largest dingoes were estimated to be 36.8% and 54.1% heavier than the smallest thylacines in the Nullarbor and southwest, respectively.

If thylacines on the mainland were typically that much smaller than dingoes, then they certainly would have been killed by dingoes.

Dingoes are derived from domestic dogs, which are derived from wolves, and we know that wolves kill jackals and coyotes where their ranges overlap.

In fact, canids  in general will kill predators that are smaller than themselves.  Red foxes kill arctic foxes. Coyotes kill red foxes.

Even today, dingoes are effective at controlling fox numbers in Australia.

So it is very possible that larger dingoes were killing thylacines.

The authors of the recent study suggest that the smaller thylacines were female, and unlike Tasmanian thylacines, these mainland individuals had significant sexual dimorphism.

If the dingoes could easily kill these smaller ones, then they were likely killing many female thylacines, and without females, the population could not be sustained.

Of course, the authors point out that all of these relationships were likely much more complex than can be concluded through simple morphological studies.

Dingoes, as feral and semi-domesticated dogs, were attached to people, and the time in which thylacines became extinct is associated with a population increase among indigenous Australians. Indigenous Australians were using fire to manage lands in order to create landscapes that were filled with prey species. They may have even been using the dingoes as hunting dogs, which would make it much easier for them to catch prey.

And if people were doing well, the dingoes likely were, too.  And if the dingoes were doing well, they could have been competing with thylacines for prey.

If their jaw structure meant that thylacines were reduced to preying on smaller animals, dingoes would have had an advantage.  They could hunt larger macropods that were out of the thylacine’s grasp, and they could very easily attack the same prey that thylacines were relying upon.

And if they were also killing thylacines, this would have been very bad for them.

After the extinction of the marsupial lions, the thylacine was the only predatory mammal of any size in Australia.

It evolved without competition.

Dingoes, as derivatives of domestic dogs that evolved from wolves, had derived from lineages that spent millions of years with lots of competition from other predators and very wily, recalcitrant prey.

The wolf had evolved pack-hunting behavior to deal with these challenges.

The thylacine, by all accounts, had not.

One way of interpreting the wolf’s success is that certain wolves evolved to have a relationship with humans. We call the descendants of these wolves domestic dogs. Dingoes are derivatives of domestic dogs, and virtually all accounts suggest that they had some sort of relationship with the indigenous people of Australia.

Thylacines had no relationships with anyone.

The cards were clearly stacked against the mainland thylacine when it went extinct.

Humans were changing the landscape through fire– which allowed human populations to increase.  But that same fire got rid of the forested habitat that thylacines preferred to use to ambush their prey.

And the success of humans also meant that the dingo’s numbers would increase.

And dingoes were much more efficient and generalized predators than thylacines were.

And the dingoes may have considered these mainland thylacines prey.

It was not a good situation for a predator that had spent so many thousands of years evolving without competitors.

And in this case, dingoes were an invasive species.

Over time, they became native, but not after being possibly implicated in the extinction of the mainland thylacine and Tasmanian devil.

It’s not a smoking gun, but dingoes certainly had the opportunity.

 

 

 

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“Ashy pouched bear”

From The fur traders and fur bearing animals (1914) by Marcus Petersen:

While not as important commercially as the Common Phalanger, the skins of the Koala are used extensively in the manufacture of sleeping bags, coats and other articles where a durable, reasonable priced fur is desired. The scientific designation of this animal signifies Ashy Pouched Bear, which is a very good description of it. The Koala is strictly arboreal, the natives often being obliged to follow it to the top of the highest trees sixty and seventy feet above the ground.

The Koala is the largest Australian mammal living in the trees and that is probably the reason why it is called the bear by the natives, as it is unlike that animal in its nocturnal habits as well as its slow movements, in both of which characteristics it resembles the sloth.

It is from eighteen to twenty-four inches long, and the general color is a light grey, the tips of the coarse hair being white. The upper part of the belly and chest and the insides of the legs are white, and the lower part of the belly is reddish brown, at times approaching to a dark purple hue. The fur on the hind quarters is much shorter than on the rest of the body, and has patches and spots of white. The ears are very short, tufted on the inside with long white hairs. The head, which is broad and short, is surrounded with a fringe of hair. The nose is bare, and whiskers are absent. The formation of the feet is singular, the claws of the fore-paws being five in number, the two inner ones opposable to the toes like the thumb of a man to the fingers of the hand. The next two toes are small and joined together, and the fourth, which is the longest, is separate, as is also the fifth which however is somewhat shorter (pg. 263-264).

The fur trade just about did the koala in in the early twentieth century.

It was one of the first marsupials in Australia to be protected, and it currently has healthy numbers, although it is rare or extinct in some parts of its former range

 

 

 

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