Photo: Tsvangirayi Mukwazhi, Associated Press
In this photo taken on Thursday, Oct. 1, 2015, an elephant crosses the road in Hwange National Park, about 700 kilometers south west of Harare, Zimbabwe. Cyanide poisoning has killed 22 elephants in Zimbabwes Hwange National Park, the Zimbabwe National Parks and Wildlife Management Authority said on Monday, Oct. 26, 2015. This brings to 62 the number of elephants poisoned by poachers in this southern Africa country in October.
In this photo taken on Thursday, Oct. 1, 2015, an elephant crosses the road in Hwange National Park, about 700 kilometers south west of Harare, Zimbabwe. Cyanide poisoning has killed 22 elephants in Zimbabwes
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Aisling Farrell cleans a Columbian mammoth pelvis at the La Brea Tar Pits.
Aisling Farrell cleans a Columbian mammoth pelvis at the La Brea Tar Pits.
Photo: Wire Photo
The Western Black Rhinoceros was officially declared extinct by the International Union for the Conservation of Nature. It was hunted into oblivion by poachers, feeding the market for "traditional Chinese medicine." In Africa as a whole, the population of black rhinos has plummeted from 70,000 in 1970 to between 2,300 and 4,000 animals today.
The Western Black Rhinoceros was officially declared extinct by the International Union for the Conservation of Nature. It was hunted into oblivion by poachers, feeding the market for "traditional Chinese
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Vancouver Aquarium director of animal operations Dr. Dennis Thoney holds a Panamanian golden frog at the aquarium in Vancouver, British Columbia on Thursday March 27, 2014. The aquarium has successfully bred the frogs, thought to be extinct in the wild, as part of a worldwide effort to preserve the species. They are native to the mountainous, higher-altitude regions of western-central Panama and the goal is to eventually re-populate their natural habitat in the country.
Vancouver Aquarium director of animal operations Dr. Dennis Thoney holds a Panamanian golden frog at the aquarium in Vancouver, British Columbia on Thursday March 27, 2014. The aquarium has successfully bred
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In this Nov. 29, 2012 photo, Keeper Shannon Smith gets a lick from Shiley, a 3-and-half-year-old male cheetah, during a animal ambassador walk through at Safari Park, in Escondido, Calif. Cheetahs might be the fastest mammals in the world, but they are also the world's biggest scaredy-cats. The tightly wound, timid, flight-minded, anti-social creatures don't breed easily and are in danger of going extinct in the wild and in captivity.
In this Nov. 29, 2012 photo, Keeper Shannon Smith gets a lick from Shiley, a 3-and-half-year-old male cheetah, during a animal ambassador walk through at Safari Park, in Escondido, Calif. Cheetahs might be the
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A 14 month old Tasmanian Devil bares its teeth at Devil Ark in the Barrington Tops area of Australia's New South Wales state, in this photo taken on April 27, 2012. At Devil Ark situated deep in eastern Australia's cattle and thoroughbred country, a group of endangered Tasmanian Devils are being taught to forage in the wild as researchers race a contagious cancer threatening the species with extinction.
A 14 month old Tasmanian Devil bares its teeth at Devil Ark in the Barrington Tops area of Australia's New South Wales state, in this photo taken on April 27, 2012. At Devil Ark situated deep in eastern
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A couple of spot-billed toucanets are pictured at the zoo in Rio de Janeiro, Brazil on Tuesday, March 9. These toucanets were the first to be born of their species in captivity in the zoo. According to biologists, the spot-billed toucanet is at risk of extinction.
A couple of spot-billed toucanets are pictured at the zoo in Rio de Janeiro, Brazil on Tuesday, March 9. These toucanets were the first to be born of their species in captivity in the zoo. According to
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A female anteater carries her baby at the zoo in Rio de Janeiro, Brazil. The baby is the first to be born of its species in captivity at the zoo. According to biologists, the anteater is at risk of extinction.
A female anteater carries her baby at the zoo in Rio de Janeiro, Brazil. The baby is the first to be born of its species in captivity at the zoo. According to biologists, the anteater is at risk of extinction.
Photo: Getty Images
A sacred ibis baby waits for its mother to bring food at the zoo in Rio de Janeiro, Brazil. Biologists in Rio de Janeiro's zoo work on the reproduction of species that are at risk of extinction.
A sacred ibis baby waits for its mother to bring food at the zoo in Rio de Janeiro, Brazil. Biologists in Rio de Janeiro's zoo work on the reproduction of species that are at risk of extinction.
Photo: Getty Images
A guara bird takes flight at the zoo in Rio de Janeiro, Brazil. The species is of the Amazonian area, in northern Brazil, and according to biologists, it is at risk of extinction, but was able to be reproduced in the zoo.
A guara bird takes flight at the zoo in Rio de Janeiro, Brazil. The species is of the Amazonian area, in northern Brazil, and according to biologists, it is at risk of extinction, but was able to be reproduced
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Yellow-spotted Amazon River turtles mate at the zoo in Rio de Janeiro, Brazil. This species, of the Amazonian region in northern Brazil, is at risk of extinction but can be easily reproduced in captivity according to biologists.
Yellow-spotted Amazon River turtles mate at the zoo in Rio de Janeiro, Brazil. This species, of the Amazonian region in northern Brazil, is at risk of extinction but can be easily reproduced in captivity
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A captive Sumatran tiger pads through its enclosure at Jakarta's Ragunan Zoo. The Indonesian government has hatched a plan to save the endangered tigers from extinction by allowing people to adopt captive-born animals as pets for 100,000 US dollars a pair officials said.
A captive Sumatran tiger pads through its enclosure at Jakarta's Ragunan Zoo. The Indonesian government has hatched a plan to save the endangered tigers from extinction by allowing people to adopt captive-born
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Two Giant Pandas take a nap at a zoo in Xian, north China's Shaanxi province on August 15, 2009. China's giant panda could be extinct in just two to three generations as rapid economic development is infringing on its way of life, citing an expert at conservation group.
Two Giant Pandas take a nap at a zoo in Xian, north China's Shaanxi province on August 15, 2009. China's giant panda could be extinct in just two to three generations as rapid economic development is infringing
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Yuri and Sasha, a pair of rare Amur tigers get fed at their new home the Highland Wildlife Park in Kincraig, Scotland. With only 500 remaining in the wild, it is hoped that the pair will continue to contribute to the worldwide breeding programme, which acts as a safety-net against extinction.
Yuri and Sasha, a pair of rare Amur tigers get fed at their new home the Highland Wildlife Park in Kincraig, Scotland. With only 500 remaining in the wild, it is hoped that the pair will continue to contribute
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A koala yawns as he sits on a branch at Koala Park in Sydney, Australia, Tuesday, July 27, 2004. Animal activists urged the government Wednesday, July 28, 2004 to make koala protection an election issue, as they presented evidence that urban sprawl is driving the much-loved marsupial toward extinction. The Australian Koala Foundation delivered a dossier of evidence to government scientists to support its prediction that koalas will disappear from the populous eastern seaboard within 15 years if the eucalyptus trees whose leaves they eat continue to be cleared to make way for new homes and farmland.
A koala yawns as he sits on a branch at Koala Park in Sydney, Australia, Tuesday, July 27, 2004. Animal activists urged the government Wednesday, July 28, 2004 to make koala protection an election issue, as
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Big animals’ extinction forever alters environment, study shows
Extinctions of large animals — a fate that could soon befall elephants and rhinoceroses — have a cascade effect on local ecosystems, including Northern California, where many smaller animals and plants died off after mammoths were wiped out, a team of scientists has discovered.
The size of elephants, wildebeests and other big plant-eaters makes them not only impressive and fascinating but also vital to the many species that live with and depend on them, according to a joint report by UC Berkeley, Stanford University, California State University Sacramento and the University of Chile.
“Ecological studies have shown that if you pull out a top predator or a key herbivore today, you get dramatic change in the ecosystem,” said Anthony Barnosky, a UC Berkeley professor of integrative biology and the study leader. “Our study makes it clear that in the past, such changes have lasted for thousands of years. These extinctions really do permanently change the dynamics. You can’t go back.”
The study, which was released Monday and is to be published in the journal Proceedings of the National Academy of Sciences, looked at extinctions in North and South America since humans arrived about 15,000 years ago.
The scientists found that the number and diversity of small animals and vegetation decreased all along the Pacific Northwest, as well as the western and northeastern United States, after mammoth and mastodon extinctions. In Alaska and the Yukon, what was once a mix of forest and grassland became mostly tundra after the loss of mammoths, native horses and other large animals, according to the study.
Nowhere has the change been more dramatic than in the Bay Area. Columbian mammoths were among thousands of now-extinct animals that roamed the region as late as 12,000 years ago. The shoreline was 12 miles farther out at that time, and a vast plain stretched from the Golden Gate, where a fast-moving river flowed, to the Farallon Islands.
Herds of mammoths, mastodons, camels, horses, llamas, elk, tapirs, moose and bison would have darkened the Farallon Plain. Mingling with these great herbivores were predators like the short-faced bear, saber-tooth cat, wolf packs and prides of California lions.
Some 60 large mammals have died out in North America since that time.
The situation is relevant today because previous studies have concluded that Earth is in the midst of a sixth mass extinction. A report published in June in the journal Science Advances found that animals are going extinct at a rate 100 times faster than they should. It concluded that humans are polluting the ecosystem, destroying habitat and killing off species at a rate so rapid that the demise of animals like elephants, tigers, rhinoceroses and others could occur within three human lifetimes.
The study released Monday explains how large browsing animals like mammoths, mastodons and today’s elephants, bison and moose change the ecosystem by eating small trees and shrubs, uprooting trees and trampling and churning up soil. They also distribute seeds and change nutrients in the soil when they defecate and urinate, according to the study.
The result is more open grasslands, fewer overgrown forests and a different mix of animals and plants.
“You see the impact of defaunation today in Africa, where the removal of elephant populations has led to these shrubby, scraggly acacias filling the savanna landscape,” said co-author Charles Marshall, a professor of integrative biology and director of the UC Museum of Paleontology. “Africa today, with its elephant populations, seems to fit the model of North America with its mammoths and mastodons.”
Peter Fimrite is a San Francisco Chronicle staff writer. E-mail: pfimrite@sfchronicle.com Twitter: @pfimrite
http://www.sfgate.com/bayarea/article/Scientists-warning-Extinction-of-big-land-6591471.php
