• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Carnivores being displaced (1 Viewer)

Not a "paleo scientist" but I can offer you the standard explanation for the phenomenon (which I've personally always found reasonably convincing). In Africa, man and megafauna co-evolved with the result that the latter "learned" (i. e., gradually acquired the necessary adaptations via the usual evolutionary processes) that we were dangerous and to keep out of our way. In Australia, the Americas etc etc, the situation was otherwise, the fauna in these places not seeing the invading humans as a threat--why should they having never encountered our species before?--and thus falling easy prey to them.

On top of that, not only did the critters evolve alongside human hunting, but Africa as the birthplace of humanity also has had a very large number of diseases and parasites that also evolved alongside man, and which played a significant role in constraining human population growth for a considerable period of time.
 
That's very interesting Andy - so quite ancient then, and ~3500 year old genetically stable Dingoes are relatively new 'pups' on the block! .... :cat:

Yet in that short (in evolutionary or geological/paleological epoch terms), the Dingo evolved (or had infused) quantifiable differences 'in the wild'. The howling, the notably different skull structure and the once a year breeding cycle (though with most beasties in Australia 'making hay while the sun shines' with back to back good seasons, I wonder if this is a hard and fast rule for Dingoes? - for example, I've seen Black Shouldered Kites raise 10! fledglings in 3 back to back broods over ~9 months .... 4, 3, and 3, after which I think the male went off to have a well deserved heart attack! :) :eek!:

That's why I said to John it's a rather complex situation, there's no reliable way of telling a genetically pure Dingo from a first or more generation hybrid, save for measuring the inside of the dead Dingoes cleaned skull - highly illogical methodology for conserving a species!

Also, where do you draw the line? 98% pure? 95? 90? 80? other? If any of our Paleo scientists can shed light on the accepted scientific classifications of such dilutions I would be very interested ...... :cat:

Because of this difficulty in identification separation, and the absolute impossibility of physical separation (at least on the mainland), I think the 'evolving Dingo' is largely here to stay. Average size /weight increases apart, I think the major risk and potential impacts come if a genetic dilution tipping point is reached and the Dingo starts breeding twice a year like the domestic dog (gone wild) genetically does .... there could be an explosion in numbers. Some may think the Dingo a bit of a non event, but I think several thousand years of genetic purity is reasonably remarkable in this modern age ....

I will never forget walking out the back of the Kanangra-Boyd National Park, and hearing this god unholy howling coming from the 'Wild Dog' Mountains - scared the living bejayzus outta me, I can tell ya! It sounded exactly like something from out of the movie 'The Grey' .... :eek!::eek!:

Again, if any of our Paleo scientists can shed light on how Mankind and latterly, a humble dingo was able to supposedly wreak such havoc (extinctions) on indigenous Megafauna including fearsome predators like the Marsupial Lion https://en.m.wikipedia.org/wiki/Marsupial_lion in Australia, and yet Africa didn't suffer the same effects. I read the Megafaunal mass extinction summary here: https://en.m.wikipedia.org/wiki/Megafauna , but I'm still struggling to come to terms with the magnitude of the difference between Australia and Africa ???? Neither had Guns, Germs or Steel ...... https://en.m.wikipedia.org/wiki/Guns,_Germs,_and_Steel

I can't say that I totally buy the 'fire stick farming' bit https://en.m.wikipedia.org/wiki/Fire-stick_farming , if anything, to my mind fluctuations in frequency possibly occurred as a result of the disappearance of Megafauna, not as a cause .... :cat: Also I'm thinking that natural lightning induced conflagrations far outweighed the effects of man.

Can anyone scientifically explain the difference between our present day large macropod grazing conditions/ vegetation /adaptations and those of the Megafauna herbivores?

Also, is it possible that some form of large native carnivore still exists in the depths of the wilds? Or are giant feral cats the extent of it? http://www.birdforum.net/showthread.php?p=3527496#post3527496

Thanks.



Chosun :gh:

Well for starters, I doubt dingos played much role in the big megafaunal extinctions, largely because available evidence suggests that they arrived in Australia long after the first humans, so most likely most of the megafauna was already eradicated.

Secondly, there are two main routes that Humans probably snuffed the megafauna in Australia.

First, the larger the mammal, the slower the breeder (and this could have been even more enhanced for giant marsupials). If your a diprotodont that maybe only produces one offspring ever few years, it doesn't take much hunting pressure to result in negative population growth. And a good chunk of the megafauna probably would not have been terribly difficult to hunt. Again, a giant diprotodon doesn't have much in the way of defenses, nor were they particularly fast and agile Unlike on the other continents, Australian megafauna never really had to evolve ANY defense again cooperative pack endurance hunters.

Loss of several species of megafauna would have had ripple effects. First, large mammals are often keystone species that have a huge effect on their environment. They clear brush and open up habitat, preferentially feed on certain types of vegetation, spread the seeds of some species, and their dung provides important fertilizer. Wiping them out or just significantly reducing them can have a huge effect on the environment, something we have been seeing in Africa recently with the loss of elephants, and which has been used as an explanation for the Pleistocene loss of Arctic steppe habitat and Spruce Parkland, two environments that don't even exist anymore effectively. These environmental changes could have resulted in loss of other species.

The second main way proposed that humans could initiate megafaunal extinctions in Australia was through the spread of deliberate use of wildfire for hunting. Beyond just being a pretty destructive way of hunting and resulting in a lot of incidental mortality, continued use of fire can significantly alter the landscape. First, you burn up the topsoil and available nutrients for plant life, especially problematic given that Australia is geologically dead and nutrient poor compared to other continents. Secondly, fire tends to favor species which reproduce using fire, causing replacement by fire prone taxa and loss of the original flora (and even more wildfires). Repeated bouts wildfires can gradually cause desertification...which in turn can alter the local hydrology of an area and cause it to become even drier. As habitat alters, any water sensitive species or herbivores dependent on certain foliage will die off. The Geological record so far supports this above scenario playing out, and suggests that until relatively recently Australia was probably a much wetter and forested place than it is today.

As for why giant wombats went extinction but red kangaroos didn't? the simplest answer is one we see demonstrated on all of the other continents as well. Fast and/or hard to catch animals (which is a good description for Kangaroos) generally can survive a megafaunal purge
 
Well for starters, I doubt dingos played much role in the big megafaunal extinctions, largely because available evidence suggests that they arrived in Australia long after the first humans, so most likely most of the megafauna was already eradicated.

Secondly, there are two main routes that Humans probably snuffed the megafauna in Australia.

First, the larger the mammal, the slower the breeder (and this could have been even more enhanced for giant marsupials). If your a diprotodont that maybe only produces one offspring ever few years, it doesn't take much hunting pressure to result in negative population growth. And a good chunk of the megafauna probably would not have been terribly difficult to hunt. Again, a giant diprotodon doesn't have much in the way of defenses, nor were they particularly fast and agile Unlike on the other continents, Australian megafauna never really had to evolve ANY defense again cooperative pack endurance hunters.

Loss of several species of megafauna would have had ripple effects. First, large mammals are often keystone species that have a huge effect on their environment. They clear brush and open up habitat, preferentially feed on certain types of vegetation, spread the seeds of some species, and their dung provides important fertilizer. Wiping them out or just significantly reducing them can have a huge effect on the environment, something we have been seeing in Africa recently with the loss of elephants, and which has been used as an explanation for the Pleistocene loss of Arctic steppe habitat and Spruce Parkland, two environments that don't even exist anymore effectively. These environmental changes could have resulted in loss of other species.

The second main way proposed that humans could initiate megafaunal extinctions in Australia was through the spread of deliberate use of wildfire for hunting. Beyond just being a pretty destructive way of hunting and resulting in a lot of incidental mortality, continued use of fire can significantly alter the landscape. First, you burn up the topsoil and available nutrients for plant life, especially problematic given that Australia is geologically dead and nutrient poor compared to other continents. Secondly, fire tends to favor species which reproduce using fire, causing replacement by fire prone taxa and loss of the original flora (and even more wildfires). Repeated bouts wildfires can gradually cause desertification...which in turn can alter the local hydrology of an area and cause it to become even drier. As habitat alters, any water sensitive species or herbivores dependent on certain foliage will die off. The Geological record so far supports this above scenario playing out, and suggests that until relatively recently Australia was probably a much wetter and forested place than it is today.

As for why giant wombats went extinction but red kangaroos didn't? the simplest answer is one we see demonstrated on all of the other continents as well. Fast and/or hard to catch animals (which is a good description for Kangaroos) generally can survive a megafaunal purge

A very interesting and informative post. Many thanks.
 
Interesting sidebar. Now that more of the true history of the invasion and theft of Australia by Europeans is emerging, it seems there is a school of thought that the high levels of mortality of Indigenous Aborigines soon after arrival by the white man was not just due to displacement and murder, but also by the deliberate release of germ warfare. Specifically, small pox.

Regarding the Dingo, there are samples of remains from ~350 years ago which will be sent for DNA testing, with the aim of conserving the dingoes genetic purity.
https://www.msn.com/en-au/news/tech...-ago-could-save-species/ar-BBNTMjr?li=AAwmrQf




Chosun :gh:
 
Regarding your previous post: theory that Europeans deliberately released smallpox to kill natives in Australia plainly lacks any grounds. Not there is anything 'emerging'; for the ideological debates has being going on long enough to receive a name 'history wars'.
https://en.wikipedia.org/wiki/History_wars#Controversy_over_smallpox_in_Australia

Regarding dingo, I am surprised why no genetic research is done on dogs in southern Asia which are the recent ancestors of dingos. They can be potential source of 'pure dingos' if such a thing exists and is worth having.

However, more sensible than debating 'is dingo native' may be reintroducing Tasmanian Devils to some dingo-free reserves in mainland Australia. Devils are certainly native, themselves endangered, and proven to control numbers of foxes and cats.
 
Last edited:
Regarding your previous post: theory that Europeans deliberately released smallpox to kill natives in Australia plainly lacks any grounds. Not there is anything 'emerging'; for the ideological debates has being going on long enough to receive a name 'history wars'.
https://en.wikipedia.org/wiki/History_wars#Controversy_over_smallpox_in_Australia

Regarding dingo, I am surprised why no genetic research is done on dogs in southern Asia which are the recent ancestors of dingos. They can be potential source of 'pure dingos' if such a thing exists and is worth having.

However, more sensible than debating 'is dingo native' may be reintroducing Tasmanian Devils to some dingo-free reserves in mainland Australia. Devils are certainly native, themselves endangered, and proven to control numbers of foxes and cats.
Walks like a duck, quacks like a duck = is a duck ! ..... it's a bl**dy long walk from the Top End to Port Jackson !

'History Wars' is a quaint whitewashing concept. There's no debate about it. The invaders came here with express orders to steal the land, and committed genocide in the process.

I'm not schooled in the genetic similarities of the Asian dogs, but given that there is now compelling evidence of Aboriginal inhabitance as far back as ~65,000 years ago in Australia https://www.birdforum.net/showthread.php?t=364276 , one has to wonder at the origins and timing of the dingoes arrival. A number of unique and distinctive features had evolved into a distinct stable species prior to the arrival of the white man.

As I said in an earlier post, I think one of the biggest risks from the genetic pollution by feral domestic dogs to the dingo would be an increase in the breeding cycle to more than once yearly.

Has there been any research on the Tasmanian Devils predating Foxes? - they certainly don't co-exist in the wild. Likewise is there any research on their effect on Feral Cats? some of those are getting up over 20kg now .... https://www.birdforum.net/showthread.php?p=3730446#post3730446

It's an interesting concept, though Wedge-tailed Eagles also predate circa ~10% of Feral Cats and Foxes ..... perhaps we should just prevent 'farmers' from killing hundreds of these precious birds ?!




Chosun :gh:
 
On top of that, not only did the critters evolve alongside human hunting, but Africa as the birthplace of humanity also has had a very large number of diseases and parasites that also evolved alongside man, and which played a significant role in constraining human population growth for a considerable period of time.
Mysticete, thanks for your replies in this thread.

What do you make of recent discoveries of archeological evidence of Aborigines in 'Australia' as far back as 100,000ya + ? and even further, cultural story of stars falling from the sky and crashing into the earth (specifically the Wolfe Creek crater - however old that is ~ up to 300,000 years + ?).
Many details and links in this thread:
https://www.birdforum.net/showthread.php?t=364276

Also to theories of 'Out of Australia' as opposed to Africa? Even on the current evidence it seems there was coexistence between Megafauna and Aborigines for 10's and 10's and 10's of 1000's of years.

Elders tell me that they have been here "forever" and didn't come from anywhere .....

As such, they would have seen dramatic changes in climate and environment - from wetter, lusher, volcanic activity, to sea inundation, to glaciation, much colder and drier, to hotter, to catastrophic events like fireball earth's from meteorite strikes and resulting 'nuclear winters'. With the El Nino cycle, they would have lived through droughts (and conversely floods) lasting for decades.

I recall parts of a documentary I saw that postulated that ~600 years ago there was a 3 decade long drought in Australia and correspondingly 3 decades of downpour in South America which led to the extinction of some of those South American civilizations.

There was no bushfire brigade in those days (not that they can even do much today anywhere in the world when conditions are against them) , and I don't find it difficult to imagine at all that a dry lightning strike during similar conditions, which with 100km/hr winds would have burnt just about the entire country down.

It seems to me that Aboriginal use of fire was a survival tool to guard against such conflagrations though 'mosaic' landscape management. Further that the slow, cool burns used were 'pyrolyzing' adding fertility to the land through charcoal and therefore building carbon in the soil rather than CO2 in the air.

I'm not saying that accidents never happened though (changing weather conditions sending a controlled burn out of control, or fire being used for warfare, etc). By and large there was a sophisticated 'Aboriginal Nation' in place with advanced governance laws. The health of the 'country' (environment) was integral to the spiritual and physical health of the people.

What you have said previously about slower moving, more defenseless large Megafauna and longer breeding cycles makes sense. Given the evidence of man co-habitating for millenia though, I don't think it is the 'alien species (man) invasion scenario that is often thought of. Likely environmental factors have had profound compounding effects to permanently tip the balance at some stage. Even now there is story and a palpable fear of entering certain waterholes at certain times of year (this may be reference to the megafauna pythons which may have done more to contribute to the extinction of other Megafauna in extended drought periods and then evolved to smaller species or become extinct themselves - a hypothesis to consider anyway ....) . Have a look at the next post I will make about the effect of lack of Dingoes (fenced out) and the effect that is having on the environment (admittedly in the face of feral animals too).





Chosun :gh:
 
Last edited:
I thought bush or dry forest was much more abundant in native Australia, and grassland spread after humans regularly burned shrub.
 
I thought bush or dry forest was much more abundant in native Australia, and grassland spread after humans regularly burned shrub.
As elsewhere in the world it all depends on soil types, topography, and rainfall /prevailing weather (more closely linked to vegetation and in-soil hydrology than is widely understood) and the interaction of grazing animals and carnivores.

Apart from the heavily forested wet mountainous regions, and the rocky thinner soiled dry schlerophyll ridgetops, large areas of the country were grassy box-gum woodlands with attendent ephemeral wetlands and creek and river netkworks (inland side of dividing mountain ranges which has been mostly cleared for agricultural land, and on the coastal plains which has mostly been cleared for what are now cities).

Modern 'Western' agricultural practices that were introduced here have totally decimated fertility, topsoil volumes and native grasslands. 'Bush' is now much more prone to invade other ecotypes because the land has been drained and dried so much.



Chosun :gh:
 
Regarding low genetic diversity of Tasmanian Devil and Thylacine. Surprisingly many mammal species have naturally very low genetic diversity (among others European Badger) and are doing fine.
 
Regarding low genetic diversity of Tasmanian Devil and Thylacine. Surprisingly many mammal species have naturally very low genetic diversity (among others European Badger) and are doing fine.

Interesting. Any thoughts on why this should be?
 
Not really. Often there is no obvious reason. Maybe the relatively low dispersal of badgers forces them to mate in the pool of distant relatives. And their solitary nature and low density (outside Britain, Badgers are loners) mean that badgers can have uniform immunological system and be safe from epidemies. In case of Cheetahs, it was suggested that low genetic diversity comes from near-extinction several 10,000 years ago. However I never saw a reasonable follow-up whether there is another proof of this supposed near-extinction and why it should happen just for Cheetahs.

In any case, there are many known examples of mammal populations with low genetic diversity which are very healthy. Presumably, many genetically uniform populations by luck 'purge' genetic disorders so stay healthy.
 
Surprisingly many mammal species have naturally very low genetic diversity (among others European Badger) and are doing fine.
Just as an aside, this applies to a fair scattering of plants, too; Stone Pine (Pinus pinea; Iberia) and Red Pine (Pinus resinosa; NE North America) being two examples.
 
Warning! This thread is more than 4 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Users who are viewing this thread

Back
Top