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Ian Murray
23-12-2018, 09:47 PM
I have not heard of any serious damage to the environment due to hunting and gathering

Hunting was not too beneficial to biodiversity:

Humans Blamed for Extinction of Mammoths, Mastodons & Giant Sloths (https://www.livescience.com/46081-humans-megafauna-extinction.html)

Humans, not climate change, wiped out Australian megafauna (https://phys.org/news/2017-01-humans-climate-australian-megafauna.html)

MichaelBaron
24-12-2018, 12:55 AM
Hunting was not too beneficial to biodiversity:

Humans Blamed for Extinction of Mammoths, Mastodons & Giant Sloths (https://www.livescience.com/46081-humans-megafauna-extinction.html)

Humans, not climate change, wiped out Australian megafauna (https://phys.org/news/2017-01-humans-climate-australian-megafauna.html)

Interesting read...but if we assume that Mammoths etc were populating vast territories and it is hard to imagine. On the other hand ..anything is possible.

Ian Murray
24-12-2018, 12:15 PM
Interesting read...but if we assume that Mammoths etc were populating vast territories and it is hard to imagine. On the other hand ..anything is possible.

Don't underestimate the ruthlessness of humankind. At the present rate of extinctions, WWF has calculated that all wildlife vertebrates will be extinct by 2026.

Kevin Bonham
24-12-2018, 01:49 PM
Don't underestimate the ruthlessness of humankind. At the present rate of extinctions, WWF has calculated that all wildlife vertebrates will be extinct by 2026.

This can't be right. They have been saying that 2/3 of all "wild animals" could be gone by 2020, but that is a claim about numbers of specimens (I think compared to 1970), not a claim about species extinction rates.

Calculating past and predicting future extinction rates are both very difficult. Claims that seek to use specimen decline rates as a proxy for "mass extinction" are not scientific.

Ian Murray
24-12-2018, 02:07 PM
This can't be right. They have been saying that 2/3 of all "wild animals" could be gone by 2020, but that is a claim about numbers of specimens (I think compared to 1970), not a claim about species extinction rates.

Calculating past and predicting future extinction rates are both very difficult. Claims that seek to use specimen decline rates as a proxy for "mass extinction" are not scientific.

It's an extrapolation of the extinction rate between 1970-2010 and 1970-2012. I don't believe in the total extinctiom either, but there is ample cause for alarm.

Kevin Bonham
24-12-2018, 03:28 PM
It's an extrapolation of the extinction rate between 1970-2010 and 1970-2012. I don't believe in the total extinctiom either, but there is ample cause for alarm.

Searching for it I found this as a summary of the claim (not necessarily the original source):

http://www.climatehealers.org/mass-extinction/

Firstly, this is indeed a calculation based on estimated rates of specimen loss, which are not a valid proxy for extinction rates, though if 100% of wild vertebrate specimens are lost then that would indeed represent a mass extinction in the wild, with specimens only surviving in captivity, urban areas or outside their natural ranges.

Secondly the following breakdowns from IUCN are notable:

1970-2010 estimates:

* 39% terrestrial wildlife lost
* 39% marine wildlife lost
* 76% freshwater wildlife lost
* total 52%

1970-2012 estimates:

* 38% terrestrial wildlife lost
* 36% marine wildlife lost
* 81% freshwater wildlife lost
* total 58%

Just looking at these figures it's completely obvious the actual rate can't have gone up 6 points in 2 years since even freshwater wildlife have not gone down that much and the others are actually doing slightly better in the 2012 data set. The answer turns out to be that the lists of species used in the two lists are not the same. (see pp. 19, 20, 40, 41 at http://awsassets.panda.org/downloads/lpr_2016_full_report_low_res.pdf) Primarily, they added data on more fish species. The extrapolation from the 1970-2010 data to the 1970-2012 data is therefore unsound as they do not share the same set of species, and if they did then the 1970-2010 loss rate would have been higher and the loss over the two years 2010-12 lower.

Extinction rates are unacceptably high and this is a great concern (not necessarily just because of potential ecosystem collapses but also simply because it is sad to lose any species), but there are also some silly claims about them.

MichaelBaron
24-12-2018, 05:38 PM
Don't underestimate the ruthlessness of humankind. At the present rate of extinctions, WWF has calculated that all wildlife vertebrates will be extinct by 2026.

I am trying to think of any animals/birds that have been ''spread'' across several continents but yet got extinct over the last 100 or so years...why would it happen by 2026?

Desmond
24-12-2018, 05:44 PM
I don't foresee the Bin Chicken (https://en.wikipedia.org/wiki/Australian_white_ibis) going extinct anytime soon, they appear to be thriving.

Ian Murray
24-12-2018, 06:47 PM
I am trying to think of any animals/birds that have been ''spread'' across several continents but yet got extinct over the last 100 or so years...why would it happen by 2026?

A wildlife species with a worldwide range (if any) would obviously have a much greater chance of survival than one with a narrow range

10 Animals That Have Become Extinct in the Last 100 Years (https://www.rd.com/culture/animals-extinct-last-100-years/)
Readers Digest
Since 1900, nearly 500 species of animal have gone extinct, according to a 2015 study. The good news is, scientists are trying to bring some back.

13 rare animals that are teetering on the brink of extinction (https://www.businessinsider.com/12-rare-animals-that-are-almost-extinct-2016-7/?r=AU&IR=T/#the-bornean-orangutan-1)
Every day, species around the planet are going extinct. And for each species that goes extinct, many more become and remain endangered due to habitat loss, poaching, and climate change.

Kevin Bonham
25-12-2018, 10:37 AM
A wildlife species with a worldwide range (if any) would obviously have a much greater chance of survival than one with a narrow range

10 Animals That Have Become Extinct in the Last 100 Years (https://www.rd.com/culture/animals-extinct-last-100-years/)
Readers Digest
Since 1900, nearly 500 species of animal have gone extinct, according to a 2015 study. The good news is, scientists are trying to bring some back.

That said, four of these 10 extinct "species" (heath hen, Caspain tiger, Pyrenean ibex, Western black rhino) are currently considered to be subspecies - they are not currently considered to be full species extinctions. And while the golden toad is probably extinct, it has only been missing for 29 years. Another toad declared extinct by IUCN in the same area was rediscovered. IUCN has overconfidently declared many species extinct only for them to be found again. In my own field (land snails) there was a particularly bad case of this where the Aldabra banded snail was declared extinct on the basis of inadequate surveying and used as a poster species for climate-change caused extinction, only to be rediscovered.

Kevin Bonham
25-12-2018, 10:43 AM
I am trying to think of any animals/birds that have been ''spread'' across several continents but yet got extinct over the last 100 or so years...why would it happen by 2026?

Not that many species are naturally spread across several continents. Some migratory birds are very vulnerable. The Eskimo curlew, which bred in the north of North America but migrated to South America and sometimes Europe, is a possible example of such an extinction but its extinction is still unconfirmed.