Guest post by Dr. Craig Loehle
Last year, Willis Eschenbach had a WUWT post about extinction rates being exaggerated in the literature. I offered to help him get this published, and it is now out. We conclude that the extinction crisis for birds and mammals is very specific to island fauna which are uniquely sensitive to human impacts, including our pets and commensals like rats. It is not valid to extrapolate these extinctions to either the problem of deforestation on continents or to future impacts of climate change.
The process of getting this published was relatively painless which is surprising given how much we counter conventional wisdom in it. The paper is available free at Researchgate.
I would argue that blogs CAN be a real part of the scientific process. I would recommend that people follow up on good ideas they see and get them into print as this example illustrates.
Loehle, C. and W. Eschenbach. 2011. Historical Continental Bird and Mammal Extinction Rates. Diversity & Distributions DOI: 10.1111/j.1472-4642.2011.00856.x
Methods: We examined historical extinction rates for birds and mammals and contrasted island and continental extinctions. Australia was included as an island due to its isolation.
Results: Only six continental birds and three continental mammals were recorded in standard databases as going extinct since 1500 compared to 123 bird species and 58 mammal species on islands. Of the extinctions, 95% were on islands. On a per unit area basis, the extinction rate on islands was 177 times higher for mammals and 187 times higher for birds than on continents. The continental mammal extinction rate was between 0.89 and 7.4 times the background rate, whereas the island mammal extinction rate was between 82 and 702 times background. The continental bird extinction rate was between 0.69 and 5.9 times the background rate, whereas for islands it was between 98 and 844 times the background rate. Undocumented prehistoric extinctions, particularly on islands, amplify these trends. Island extinction rates are much higher than continental rates largely due to introductions of alien predators (including man) and diseases.
Main Conclusions: Our analysis suggests that conservation strategies for birds and mammals on continents should not be based on island extinction rates, and that on islands the key factor to enhance conservation is to alleviate pressures from uncontrolled hunting and predation.
Table 1: Extinctions since 1500 according to IUCN and CREO, with per species and per unit area rates.
Abstract:
Loehle, Craig, and Willis Eschenbach. 2011. Historical bird and terrestrial mammal extinction rates and causes.
Diversity and Distributions. doi: 10.1111/j.1472-4642.2011.00856.x
We examined historical extinction rates for birds and mammals and contrasted island and continental extinctions. Australia was included as an island because of its isolation. Only six continental birds and three continental mammals were recorded in standard databases as going extinct since 1500 compared to 123 bird species and 58 mammal species on islands. Of the extinctions, 95% were on islands. On a per unit area basis, the extinction rate on islands was 177 times higher for mammals and 187 times higher for birds than on continents. The continental mammal extinction rate was between 0.89 and 7.4 times the background rate, whereas the island mammal extinction rate was between 82 and 702 times background. The continental bird extinction rate was between 0.69 and 5.9 times the background rate, whereas for islands it was between 98 and 844 times the background rate. Undocumented prehistoric extinctions, particularly on islands, amplify these trends. Island extinction rates are much higher than continental rates largely because of introductions of alien predators (including man) and diseases. Our analysis suggests that conservation strategies for birds and mammals on continents should not be based on island extinction rates and that on islands the key factor to enhance conservation is to alleviate pressures from uncontrolled hunting and predation.
Copyright © 2011 by Blackwell Publishing Ltd. All rights reserved. Article posted on this website with permission.
Download the paper 
(Adobe PDF) Loehle & Eschenbach2011
Craig & Willis:
Well done. I have been saying that human influence >>> climate for a long time, in fact I always challenge people to name one species that has been wiped out because of climate change, and have never yet had a satisfactory example given me. Where attribution is known, it’s normally got our name on it somewhere.
DocMartyn: you mention the Javan rhino. The thought occurs that maybe WWF could have spent a few tens of thou on full time armed guards and shaved a bit off climate advocacy spending.
But one rhino is, in the end, the last of a locally extinct species. They should have tranq’d it and sent it to Java, where the last 50 may be *just* viable. It would be ironic indeed if we have room for 7,000,000,000 people but not 50 rhinos, eh?
Sparks: Think about it. We accidentally introduced rats to a lot of islands where they were unknown. That alone was devastating for local fauna. Other introductions, planned or accidental, have been equally painful. Then there’s hunting. Including by idiots who think rhino horn is magic or somethin’. (See above.)
Your list includes the lagoon spire snail. This was never thought to be *globally* extinct, only in the *UK*. Haven’t the time to check the other 105 – happened to know a little about the snail! But you do raise a philosophical point. When do we declare a species “deceased”? Easier to do with a rhino than a minute snail. For many species this will be “presumed” for a long time – hence the “Lazarus” list.
Tom Harley says:
October 25, 2011 at 11:48 pm
Thanks to Craig and Willis for this thoughtful paper. Here in the NW of Western Australia, we are about to go through major species reduction due to the advancing cane toad, foxes have just reached the Kimberley, camels and donkeys are now widespread, and introduced weeds are spreading rapidly, it just seems like a never-ending invasion……………
————————————Tom, imagine how the Aborigine felt.
For a creature to be known to have become extinct, first it must have been known to exist. Is it possible that an island’s fauna is more likely to be documented than that of the the interior of a continent and that this might affect the outcome of the research?
Congrats, and with appreciation!
Congratulations! I read the paper and it makes perfect sense to me. Once again, models have been proved to be lacking. Seems sad that the present era might be known in the future as “The Age of Modelling Hypochondriasis”.
Well done!
Best,
J.
“richardjamestelford says:
October 26, 2011 at 3:22 am
…….This makes the most important conclusion of the paper very susceptible to questions like “Is the ivory-billed woodpecker extinct?” If it is extinct, that bird alone would increase your continental extinction rates by 1/6………”
That’s a “what if” not supported by the available data and therefore outside the scope of their paper. I am a photographer and one of my specialties is Avian photography. I’ve delved quite a bit into the Ivory-billed woodpecker situation and have been tempted to go on a search for it. It seems to be alive and well in Arkansas: http://www.birdinginarkansas.com/birding/ivory-billed-woodpecker.aspx
And, it is almost impossible to mistake the Ivory-billed with the common Pileated by anyone with enough bird-watching and avian photography experience . Here is an image sequence of a Pileated made by yours truly: http://www.josesuroeditorial.com/Nature/Nonpasserines/Woodpeckers/2791726_kZdGMn#424297743_BqSUA-O-LB
It looks nothing like an Ivory-billed…..
Best,
J.
Someone asked what about Australia: we did calculations both ways (shows they did not read the paper), but if you count australia as a continent you have to ask why most of the mammal extinctions are marsupials. Marsupials are the losers when they encounter modern mammals, as happened when North & South America joined up 2 million yrs ago and modern mammals moved south.
People are listing various species extinct to make some sort of point. Many of those listed are subspecies, like a rhino, bear, lion that were mentioned. Some are not officially confirmed–we used a standard database to avoid subjectivity. Many species thought extinct are later found again.
Jit, if you ever want an example of the complexity of existence and the inability of humans to forecast the future, think on this: The greatest factor in the survival of the rhinoceros over the last 20 years has been the development of a failed heart drug.
Prior to the emergence of Viagra, powdered rhino horn was the de facto anti-impotence treatment throughout the Middle East and South East Asia. Viagra works much better than sympathetic magic and the price of rhino horn dropped through the floor.
However, don’t think that anti-impotence sympathetic magic was restricted to the third world and we sophisticated Westerners didn’t fall for it. The introduction of Viagra also destroyed the market for many psychiatrists and psychotherapists who managed to convince middle aged men that all their troubles stemmed from childhood sexual conflicts.
Amazingly, the same practitioners now focus their laser sharp minds, and peddle their sympathetic magic, on childhood behavioral problems.
Congratulations Craig and Willis. After reading the (excellent) paper I agree with your conclusions. A well written piece and logically laid out.
One quibble I have concerns the separation of island and continent. It is obvious (from your paper) that island extinctions are dramatically higher and those extinctions cannot be used to estimate continental ones. After all, on a continent there is the greater possibility of movement to a new (similar) habitat compared to islands.
However, there are continental features (and oceanic ones) that for awhile may support the long term adaptation of a species but then suddenly can disappear. For example, within a valley blocked by mountains in which a catastrophe (volcano, land-slide from earth quakes, man-made lake for hydro power etc) occurs, species could be wiped out instantly. Another example would be marine life living along the continental shelf where over-fishing occurs, eventually wiping out the species because they can only survive on the shelf.
I raise this issue (that continents can have island-like habitats) because as humans increase their influence over the earth’s surface, this will increase the likelihood of extinctions as certain species are pushed into a corner from which they cannot adapt. We (humans) are creating more continental island-habitats. It would make sense to quantify the adaptability of a species and protect the habitats of the ones that cannot adapt (if we even want to be in the species preservation game).
Craig, I understand your point, but submit that your classification is too narrow.
I agree that the actual definition of a species and an ‘island’ is problematic.
However, one would suspect that any potential extinction stress would be better modeled using a power law whereby one estimates the actual size of the ecological niche and the species specialization.
Extinction events occur much more frequently in specialist species than in generalist species.
Extinction events occur much more frequently in geographically isolated species than in geographically dispersed species.
I will point out that both the Great Auk and the Passenger Pigeon were generalist and geographically dispersed species. These two species are extinct due to the impact of humans and are not included in your list.
You may not think that this is unimportant or an illegitimate criticism. I would however like to know why you think that to be the case.
One of the major criticisms leveled at various papers issued by proponents of CAGW is the issue of ‘cherry-picking’. I believe that one can make the same criticism of your criteria for species selection.
I think it reasonable they you address these criticisms, in my own case, why did you not include the Great Auk and the Passenger Pigeon?
Good paper Craig, Willis. Thank you very much!
Craig Loehle says:
October 26, 2011 at 6:40 am
People are listing various species extinct to make some sort of point. Many of those listed are subspecies, like a rhino, bear, lion that were mentioned. Some are not officially confirmed–we used a standard database to avoid subjectivity. Many species thought extinct are later found again.
—
It does not matter how good your methods are, if the raw data are inadequate, the results may be meaningless. Many mammal species are listed by the IUCN as data deficient. You have assumed that none of these are extinct. If this enormous assumption is seriously violated, your conclusion that species are robust to habitat loss will be unsupportable.
As someone who has actually worked in the endangered species conservation field, I have to second other commenters here on the waste of attention and resources spent on climate change.
The CO2 obsession has taken up a lot of money that could’ve been far more effectively spent, and I’ve been tearing my hair out over it for years. I’ve even talked to “environmentalists” who said they would knowingly advocate for wind turbines that kill endangered birds and bats because the problem of CO2, Satan’s molecule, is so much more urgent.
Willis, will there be a Press Release?
Craig Loehle said in his lead-off post,
From the Loehle & Eschenbach 2011
Craig,
Have you tried to express quantitatively the uncertainties of the background rates of extinction?
John
The point of including Australia as an island is to identify the CAUSES of extinction. The primary cause of extinction is the introduction of foreign species that can take over the ecosystem with no competition. In the past 200 years, dogs, horses, cows, and camels have all been introduced to Australia. Rats killed the majority of Pacific Island flightless birds, and dogs have taken care of much of the rest. The point is that you cannot extrapolate these extinction rates to say X acres of forest loss means Y number of species go extinct.
John, I think that the order of magnitude range in percentage of background rate is a good indication about just how well we know that rate.
DocMartyn: passenger pigeon is listed in our Table 1. Great Auk I think we treated as an island species.
John Whitman: we could find no way to quantify the uncertainty of background rates of extinction. We listed all the estimates we could find. They are all very squishy.
Craig,
Thank you for your quick reply. OK, squishy.
Here is a little humorous personal anecdote wrt squishy.
My father used to say, “You are born screaming. Then life is squishy. Then you die.” He would pause solemnly for a minute to let the somber thought sink in. Finally, he would smile and say, “But the squishy part is really, really nice.”
John
Craig, I do apologize, I need new glasses. I didn’t read Table 1 correctly.
I was looking for E. migratorius
In Table 1 you have
Passenger pigeon (C. carolinensis)
Conuropsis carolinensis is of course the extinct Carolina Parakeet (Conuropsis carolinensis) mentioned two places above.
The extinct Passenger pigeon would be correctly labeled Ectopistes migratorius.
The Great Auk ranged from Newfoundland, Greenland, Iceland, Ireland, Scotland, Norway and Finland.
One could make the argument that all the nesting sites were coastal and they favored islands, but I do not think that they can be counted as an Island species.
jamie says:
October 26, 2011 at 1:58 am
It was published last year, in Energy and Environment.
w.
@DocMartyn,
Why don’t you take the data from the paper and reanalyze it the way you want and show if the results change significantly, or not.
Also, definition of species is not difficult. Any two organisms that can interbreed and produce live offspring are a species. There are some caveats that have been used to inflate the number of species by saying some sub populations don’t overlap in geography/breeding time enough to allow proper mixing, but in the end they still do interbreed.
None the less, you can always use -whatever definition you want- and re-do the analysis under those new criteria, and then come to us with the results, why don’t you. I see absolutely nothing in your arguments that were not already considered and addressed both by this paper and the curated source data it’s based on. In short, all you’re saying has no merit as far as I can see, and it’s up to you to prove otherwise with factual data points and outlined criteria.
@DocMartyn,
By “live” offspring, I meant to say “viable”. That is, the offspring can produce offspring, ensuring biological continuity.
Also, I think the main point of it all, is if you change your criteria for analysis, the numbers for -both- continental and island are going to be changed. Are you proposing the ratio between island and continent would significantly change under new criteria away from the results of this paper? Show us the evidence by doing the analysis if you believe so.