Wildlife extinction rates 'seriously underestimated'

by Amy Judd | July 4, 2008 at 10:03 am

1864 views | 14 Recommendations | 28 comments

Scientists have discovered that endangered species may become extinct 100 times faster than previously thought - which is a bleak re-assessment of the threat to global biodiversity.

Writing in the journal Nature, leading ecologists claim that methods used to predict when species will die out are seriously flawed, and dramatically underestimate the speed at which some plants and animals will be wiped out.

The findings suggest that animals such as the western gorilla, the Sumatran tiger and the Malayan sun bear, the smallest of the bear family, may become extinct much sooner than conservationists feared.

Ecologists Brett Melbourne at the University of Colorado at Boulder and Alan Hastings at the University of California, Davis, said conservation organisations should use updated extinction models to urgently re-evaluate the risks to wildlife.

"Some species could have months instead of years left, while other species that haven't even been identified as under threat yet should be listed as endangered," said Melbourne.

The warning has particular implications for the International Union for the Conservation of Nature, which compiles an annual "red list" of endangered species. Last year, the list upgraded western gorillas to critically endangered, after populations of a subspecies were found to be decimated by Ebola virus and commercial trade in bush meat. The Yangtze river dolphin was listed as critically endangered, but is possibly already extinct.

The researchers analysed mathematical models used to predict extinction risks and found that while they included some factors that are crucial to predicting a species' survival, they overlooked others. For example, models took into account that some animals might die from rare accidents, such as falling out of a tree. They also included chance environmental threats, such as sudden heatwaves or rain storms that could kill animals off.

But the two researchers also looked at some different factors that would affect the rate of extinction.

But Melbourne and Hastings highlighted two other factors that extinction models fail to include, the first being the proportion of males to females in a population, the second the difference in reproductive success between individuals in the group. When they factored these into risk assessments for species, they found the danger of them becoming extinct rose substantially.

"The older models could be severely overestimating the time to extinction. Some species could go extinct 100 times sooner than we expect," Melbourne said.

The researchers showed that the missing factors - the number of males to females, and variations in the number of offspring - were capable of causing unexpected, large swings in the size of a population, sometimes causing it to grow, but also increasing the risk that a population could crash and become extinct.

More that 16,000 species all over the world are currently being threatened with extinction.

One in four mammal species, one in eight bird species and one in three amphibian species are on the organisation's red list. An updated list is due to be published in October.

This site shows all the animals that are either endangered or extinct and the list is long and depressing.

An Independent article last year, talks about how a species becomes endangered.

In the final stages of dehydration the body shrinks, robbing youth from the young as the skin puckers, eyes recede into orbits, and the tongue swells and cracks. Brain cells shrivel and muscles seize. The kidneys shut down. Blood volume drops, triggering hypovolemic shock, with its attendant respiratory and cardiac failures. These combined assaults disrupt the chemical and electrical pathways of the body until all systems cascade toward death.

Such is also the path of a dying species. Beyond a critical point, the collective body of a unique kind of mammal or bird or amphibian or tree cannot be salvaged, no matter the first aid rendered. Too few individuals spread too far apart, or too genetically weakened, are susceptible to even small natural disasters: a passing thunderstorm; an unexpected freeze; drought. At fewer than 50 members, populations experience increasingly random fluctuations until a kind of fatal arrhythmia takes hold. Eventually, an entire genetic legacy, born in the beginnings of life on earth, is removed from the future.

Scientists recognise that species continually disappear at a background extinction rate estimated at about one species per million per year, with new species replacing the lost in a sustainable fashion. Occasional mass extinctions convulse this orderly norm, followed by excruciatingly slow recoveries as new species emerge from the remaining gene-pool, until the world is once again repopulated by a different catalogue of flora and fauna.

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René

at 14:08 on July 4th, 2008

Human encroachment on wildlife habitat is the most serious danger to endangered species.

Amy Judd

at 15:10 on July 4th, 2008

I agree and it is something that is not taken into consideration until after the fact and the habitat is already gone.

René

at 15:34 on July 4th, 2008

it's happening now in India and in Africa.

danesller0127

at 14:51 on July 4th, 2008

WWF safeguards hundred of species around the world, but the focus special attention to the: giant pandas, tigers, endangered whales and dolphins, rhinos, elephants, marine turtles, and great apes.

These species not only need special measures and extra protection in order to survive, they also serves as unbrella species.

From the start in 1961, WWF has worked to protect endangered species.

René

flagged this story as Good Stuff

at 14:57 on July 4th, 2008

amyjudd, I like this story. It's good stuff.

Barbara McPherson

flagged this story as Good Stuff

at 17:23 on July 4th, 2008

amyjudd, I like this story. It's good stuff. Yeah, it's really depressing. It's usually the big and beautiful that get the attention while the small and ugly are ignored. Try to get people interested in preserving lumpy old frogs. The new Sea to Sky Highway just wiped out an enclave of endangered frogs, but it saved the province $5 mil. Was that a bargain?

lapettit

at 21:18 on July 4th, 2008

This is a photo of a female Malayan Sun Bear at the St. Louis Zoo in Missouri. I was able to capture these photos of her when she was let out first thing in the morning, and the zoo keepers had put out the "yogurt" snack for her and the male that share the habitat. I was patient enough to get a picture of the infamous "necklace".

lapettit has contributed a photo to this story.

Prince Bart

at 22:28 on July 4th, 2008

Sumatran Tiger, Panthera tigris sumatrae, San Francisco Zoo. She was watching over her newborn cubs and I got a little too close and she let me know.

Prince Bart has contributed a photo to this story.

wdthem

at 23:37 on July 4th, 2008

Great article - thanks!

_Karlie_

at 03:00 on July 5th, 2008

My photo is Sean the Malayan Sun bear at the Wellington Zoo in New Zealand.
He was rescued in Cambodia by Free the Bears before coming to Wellington.

_Karlie_ has contributed a photo to this story.

vkreynin

at 03:26 on July 5th, 2008

vkreynin has contributed a photo to this story.

jenniesuz

at 03:54 on July 5th, 2008

This was taken whilst I was on an expedition with Earthwatch monitoring bat species in the rainforest- many of which are threatened.
As far as I'm concerned, as long as the human population continues to treat the earth as if it belongs to them, and using up its vital resources, no breeding programmes or conservation efforts will make much difference in the long run. Pretty grim opinion I know, with myself being involved in various conservation programmes. I think such efforts need to be coupled with a re-think in at least how the western world lives,- return to simplicity, more reliant on locally produced foods, not having to rely on oil fuelled transport, throwing away the throw-away society.
Issues like this make me feel trapped, I know that any efforts I make on a personal level are pretty insignificant, but for some reason, I won't give up.
Nothing lasts forever, and the earth is included in that, but we could at least try to give it, and the rest of its inhabitants some respect while we are here.

jenniesuz has contributed a photo to this story.

writmm

at 04:41 on July 5th, 2008

I saw this beautiful bear while visiting the St. Louis Zoo. I was happy to see him in a pleasant environment (many zoos have come so far from their beginnings of just cages). I missed a shot of him yawning just as we arrived at the exhibit. His pink tongue must have been at least 12 inches long. I am grateful that zoos are helping to preserve amazing animals like the Malayan Sunbear and I hope that this article will help to encourage further research efforts and funding to protect the many animals on our planet.

writmm has contributed a photo to this story.

3BigBears

at 05:09 on July 5th, 2008

Very informative. I have learned something today. I am glad I got a chance to read this article.

3BigBears has contributed a photo to this story.

jessiesmom

at 07:12 on July 5th, 2008

I've always had a bitter sweet feeling about zoos. I love the animals and would never be able to witness them if not for zoos. However, I know they were not made to be caged even in large enclosures. This bear was playing through out the day with the other bears, and climbing the trees. As we were leaving, he was curled up in the sun taking a nap. It was the sweetest thing. But I couldnt help thinking about his natural home and family.

jessiesmom has contributed a photo to this story.

dbillian

at 11:33 on July 5th, 2008

If memory serves me correctly, this little sun bear was photographed at the Chiang Mai Zoo in Thailand.

A lot of animals in SE Asia and Asia are under extreme pressure because of population density:(

dbillian has contributed a photo to this story.

Readerr

at 13:54 on July 5th, 2008

This photo gives you a chance to *do something*. It links to *how to knit Bear Mittens for rescued Malayan Sun Bears receiving medical care from Animals Asia Foundation* , associated in the U.S. with the
Oregon Zoo, who have worked on conservation issues since the late 1800's.
It is easy knitting:they want acrylic(Orlon)not animal or plant fibers; Ravelers can check Ravelry's Project Gallery for: Bear Booties.

NP_1_816897 has contributed a photo to this story.

andri pribadi wiriasto

at 21:27 on July 5th, 2008

Every littlr thing in this world has it's own purpose,,, and also the wildlife.... Keep balance the world!!!

andri pribadi wiriasto has contributed a photo to this story.

amitch101

at 11:44 on July 6th, 2008

This photo was taken at Taronga Zoo - Sydney in Nov 2007

amitch101 has contributed a photo to this story.

macloo

at 20:17 on July 6th, 2008

(Singapore Zoo, 2005) The smallest kind of bear, also called the sun bear. I first saw these in the Seattle zoo many years ago. Their coats are fabulously glossy and sleek. Their front claws are remarkably long, in proportion to their size (about as big as an English sheepdog). One of only eight bear species in the world.

macloo has contributed a photo to this story.

johnjan99ca

flagged this story as Good Stuff

at 16:10 on July 7th, 2008

amyjudd, I like this story. It's good stuff.

Good writing. From all my travels the past two years, it's rather sad to see how much green space keeps disappearing. Just hope that somehow things turn around for the better.

dunkelberg

flagged this story as Good Stuff

at 16:10 on July 7th, 2008

Warmer weather producing more male reptiles than female, coastal development at the loss of wetlands and a continued arrogance that humans rule and the rest watch out all are but a part of this problem.

alfred_the_chicken

at 16:20 on July 7th, 2008

kolypie

at 17:06 on July 8th, 2008

These bears are just so beautiful and amazing. we actually got to see them eating a big piece of grapefruit. their claws are so long. i believe these are the most beautiful of all bears.

kolypie has contributed a photo to this story.