Question: On March 10, 2004, how many dead bison were found by biologists?
About the article "Yellowstone National Park", section "Geysers and the hydrothermal system".

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The non-native but charismatic Catalina Island bison herd has existed for nearly a century.
A herd of American Bison roam, supposedly first imported to California's Catalina Island in 1924 for the silent film version of Zane Grey's Western tale, "The Vanishing American".
However, the 1925 version of "The Vanishing American" does not contain any bison whatsoever and shows no terrain that even remotely resembles Catalina, according to Jim Watson, columnist for the Catalina Islander newspaper.
Over the decades, the bison herd grew to as many as 600 individuals.
The population currently numbers approximately 150.
Biologists found that the American Bison of Santa Catalina Island are not pure bred; 45 percent have a domesticated cow as an ancestor.
The island's bison herd is maintained and monitored by the Catalina Island Conservancy.
Although the bison are not native to the island, they play an important role in the cultural fabric of Catalina.
Therefore, the Conservancy has no plans to remove all the animals from the island.
Controlling the bison population, however, remains important for Catalina's overall ecological health.
In the past, bison were routinely removed and sent to the mainland to auction.
In 2004, the Conservancy partnered with the Morongo Band of Mission Indians, the Tongva (thought to be Catalina's original inhabitants some 7,000 years ago), and the Lakota tribe on the Rosebud Reservation in South Dakota.
A hundred bison were relocated "home" to the Great Plains.
Recently however, another solution was implemented.
The Conservancy initiated a scientific study that determined that a herd of between 150 and 200 would be good for the bison, and ecologically sound for the island.
Beginning in 2009, the herd was given animal birth control to maintain the population at around 150 animals. 
Antelope Island in Great Salt Lake, Utah, is part of Antelope Island State Park.
On the island, a semi–free-ranging population of American bison ("Bison bison, "buffalo) has been in existence since 1893.
Though the island was named for the pronghorn antelope that John C. Frémont and Kit Carson found there when they explored the Great Salt Lake, bison were later introduced and the island is now perhaps most famous for its bison herd.
The Antelope Island bison herd is significant because it is one of the largest and oldest publicly owned bison herds in the nation.
It is one of the two bison herds managed by the State of Utah, the other being the Henry Mountains bison herd.
The Antelope Island bison herd currently numbers between 550 and 700 individuals.
Other large free-ranging, publicly controlled herds of bison in the United States include the Yellowstone Park bison herd (3,500 bison), the herd in Custer State Park, South Dakota (1,300 bison), the Henry Mountains bison herd in south-central Utah (300 to 500 animals), the herd at Wind Cave National Park in South Dakota (350 bison), and the 400-strong National Bison Range Herd near Flathead Lake, Montana.
In addition, though the bison on Antelope Island are Prairie bison, which was the most common bison subspecies in North America, the bison have a distinct genetic heritage from many of the other bison herds in the United States and they are considered to be desirable as part of the breeding and foundation stock for other bison herds, because of their separate genetic heritage and some of the distinct genetic markers that are found in the population.
Buffalo watching is one of the most popular activities on Antelope Island.
In fact, the island is perhaps best known for the bison that inhabit it, and the bison are generally easily found and observed. 
The Wind Cave bison herd is considered to be genetically pure, meaning that there is no evidence of significant hybridization between these bison and cattle.
Most private and public bison herds in the United States are not genetically pure.
Genetic testing shows that there now appear to be some cattle genes present in approximately 95% of the bison surveyed in other areas.
Though the American bison (Species: "Bison bison") is not only a separate species, but a member of a separate genus from domestic cattle ("Bos primigenius"), they are genetically compatibile and American bison can interbreed freely with cattle.
Crossbreeds tend to look very much like purebred bison, so appearance is unreliable as a means of determining what is a purebred bison and what is a crossbred cow.
Many ranchers deliberately crossbred their bison with cattle, and it would also be expected that there could be some natural hybridization in areas where cattle and bison occur in the same range.
Since cattle and bison eat similar food and tolerate similar conditions, they have often been in the same range together in the past, and opportunity for cross breeding may have been common.
Most bison today are descendants of five herds that were conserved during the near-extinction event of the late 19th century.
These herds were subject to cattle crossbreeding experiments and as a result cattle genes are found throughout most bison populations.
In recent decades tests were developed to determine the source of mitochondrial DNA in cattle and bison, and it was found that most private 'buffalo' herds were actually crossbred with cattle, and even most state and federal buffalo herds had some cattle DNA.
With the advent of nuclear microsatellite DNA testing, the number of herds that contained cattle genes has increased.
Though approximately 500,000 bison exist on private ranches and in public herds, perhaps only 15,000 to 25,000 of these bison are pure and are not actually bison-cattle hybrids.
Significant public bison herds that do not appear to have hybridized domestic cattle genes are the Yellowstone Park bison herd, the Henry Mountains bison herd, which was started with bison taken from Yellowstone Park, the Wind Cave bison herd, and the Wood Buffalo National Park bison herd in Canada and herds derived from it.
A landmark study of bison genetics was undertaken by James Derr of Texas A&M University in an attempt to determine what genetic problems bison might face as they repopulate former areas.
It concluded that bison seem to be doing quite well, despite their apparent genetic bottleneck.
All of the state-owned bison herds tested contained animals with domestic cattle mitochondrial DNA, with the possible exception of the Henry Mountains bison herd of Utah.
Most national herds, except Wind Cave and Yellowstone, also appear to be hybridized.
As genetic testing improves, it may be discovered that almost all bison have some genetic inheritance from domestic cattle.
A separate study by Wilson and Strobeck, published in Genome, was done to define the relationships between different herds of bison in the United States and Canada, and to determine whether the bison at Wood Buffalo National Park in Canada and the Yellowstone Park bison herd were possibly separate subspecies, and not plains bison.
Some people had suggested that the Yellowstone Park bison were actually either of the 'athabascae' (wood buffalo) subspecies, or else that they were of an unspecified 'mountain' subspecies.
In the study, it was determined that the Wood Buffalo Park bison were actually cross breeds between plains bison and wood bison, but that their predominant genetic makeup was truly that of the expected "wood buffalo" (Bison bison athabascae).
However, the Yellowstone Park bison herd were pure plains bison ("Bison bison bison"), and not any of the other previously suggested subspecies.
This is significant for the Wind Cave bison herd, since this herd was founded, in part, with animals from the Yellowstone Park bison herd.
The bison in Wind Cave National park were also plains bison, as expected. 
John Dooly, owner of the island in 1893, with the help of William Glassman brought a herd of twelve bison to Antelope Island.
At the time American bison were nearly extinct in North America, having suffered years of over hunting and extermination during the settlement of the American West.
Biologists estimate that as many as 60 million bison roamed the western United States prior to the lands being settled by Anglo Americans.
These bison once inhabited the grasslands of North America in massive herds; their range stretched across most of what is now the United States, from Florida and New York in the east and south to the Texas/Mexico border and the Yukon Territory in Canada to the south and north and all the way west to the Pacific Coast.
The bison were an important resource for the native tribes of the western United States.
The United States Government knew this and began a campaign to rid the plains of the bison, thereby depriving the Native Americans of their most prized natural resource and making them dependent on handouts from the government.
Without the bison the Native Americans were forced to "seek peace".
Some conservationists saw that destroying the bison population was detrimental to the future of the nation and in 1874 Congress voted to stop the government sponsored slaughter.
By the 1890s approximately 800 bison remained.
Dooly purchased the bison after Glassman had failed to establish a bison preserve on the south shore of the Great Salt Lake.
Glassman had hope to attract tourists to the area with some of the few remaining bison in the United States at the time.
His venture failed and he was forced to sell some of the herd at auction.
Dooly bought the bison with the intention of supplementing his income with private bison hunts.
At approximately the same time a herd of elk was brought to the island.
The elk did not last very long due the island being a poor habitat for elk.
In 1993, 17 elk were reintroduced to the island with negative results; three drowned, three were never found, the remaining eleven survived.
However, due to the lack of a natural predator, the gray wolf, the bison thrived on the island and the herd rapidly increased in size.
The island was opened for bison hunts beginning in 1896.
The hunting of bison on the island was limited to those who could afford the $200 requested by Dooly and his ancestors.
Heavyweight boxing champion Jack Dempsey and 1920s sports writer Robert Edgren were just two of the celebrities that came to the island to shoot a bison.
Bison hunting continued on the island until 1926 when the final "Big Buffalo Hunt" eliminated all but a few of the bison.
Public sentiment changed during the 1920s and activists began to call for the protection of the herd on Antelope Island.
The hunt of 1926 was covered by "Time".
A herd of approximately 300-400 bison was culled to about 50 by a large group of hunters on horseback with modern rifles.
John Dooly had sold the herd to A. H. Leonard in 1924.
Leonard intended to sell the bison to zoos, but was not able to corral them.
He next tried to offer the island and the Antelope Island bison herd to the United States Department of the Interior.
Leonard had hoped that a national park would be established on the island therefore preserving the herd.
Time Magazine cites "Congressional apathy" for the lack of a land transfer.
Leonard was one again forced to change his business plan.
This time he wanted to expand the cattle ranching on the island and to do this the number of bison needed to be reduced.
Leonard announced a that a hunt would be held in the fall of 1926.
The hunt took place in November, but not without protests from around the nation.
The New York World and other newspapers of the day tried to arouse public sentiment against the hunt.
Utah governor George Dern received formal protests of the hunt from the American Humane Society, Massachusetts governor Alvan T. Fuller and Boston mayor Malcolm Nichols.
Governor Dern declined to prevent the hunt stating, "Antelope Island and the buffalo herd are privately owned."
The hunt took place with noted participants Ralph and Edward Ammerman of Scranton, Pennsylvania and big game hunter J. O. Beebe of Omaha, Nebraska.
The Antelope Island bison herd and the island remained in private hands until 1969 when the northern of the island were purchased by the state of Utah.
The southern end of the island was acquired in 1981, granting the entire herd protected status on Antelope Island State Park.
In 1986, park rangers saw the need to begin controlling the bison population to prevent overgrazing and disease.
The first "roundup" was held in 1987 and it has since become an annual event that brings in revenue by way of the sale of excess bison and tourist dollars brought in by spectators. 
The Henry Mountain bison herd is considered to be genetically pure, meaning that there is no evidence of significant hybridization between these bison and cattle.
This genetic purity appears to be different from the Antelope Island bison herd, also managed by the State of Utah.
In the Antelope Island bison herd, there now appear to be some cattle genes present.
Officially, the "American Buffalo" is classified by the United States Government as a type of cattle, and the government allows private herds to be managed as such.
This is a reflection of the characteristics that bison share with cattle.
Though the American bison ("Bison bison") is not only a separate species, but actually in a separate genus from domestic cattle ("Bos primigenius"), they clearly have a lot of genetic compatibility and American bison can interbreed freely with cattle.
Moreover, when they do interbreed, the crossbreeds tend to look very much like purebred Bison, so appearance is completely unreliable as a means of determining what is a purebred bison and what is a crossbred cow.
Many ranchers have deliberately cross bred their cattle with bison, and it would also be expected that there could be some natural hybridization in areas where cattle and bison occur in the same range.
Since cattle and bison eat similar food and tolerate similar conditions, they have often been in the same range together in the past, and opportunity for cross breeding may sometimes have been common.
In recent decades tests were developed to determine the source of mitochondrial DNA in cattle and bison, and it was found that most private 'buffalo' herds were actually cross bred with cattle, and even most state and federal buffalo herds had some cattle DNA.
With the advent of nuclear microsatellite DNA testing, the number of herds that contained cattle genes has increased.
Though approximately 500,000 bison exist on private ranches and in public herds, some people estimate that perhaps only 15,000 to 25,000 of these bison are pure and are not actually bison-cattle hybrids.
"DNA from domestic cattle (Bos taurus) has been detected in nearly all bison herds examined to date."
Significant public bison herds that do not appear to have hybridized domestic cattle genes are the Yellowstone Park bison herd, the Henry Mountains bison herd which was started with bison taken from Yellowstone Park, the Wind Cave bison herd and the Wood Buffalo National Park bison herd and subsidiary herds started from it, in Canada.
A landmark study of bison genetics that was performed by James Derr of the Texas A&M University corroborated this.
The Derr study was undertaken in an attempt to determine what genetic problems bison might face as they repopulate former areas, and it noted that bison seem to be doing quite well, despite their apparent genetic bottleneck.
One possible explanation for this might be the small amount of domestic cattle genes that are now in most bison populations, though this isn't the only possible explanation for bison success.
In the study cattle genes were also found in small amounts throughout most herds.
"The hybridization experiments conducted by some of the owners of the five foundation herds of the late 1800s, have left a legacy of a small amount of cattle genetics in many of our existing bison herds."
He also said, "All of the state owned bison herds tested (except for possibly one) contain animals with domestic cattle mtDNA."
It appears that the one state herd that had no cattle genes was the Henry Mountains Bison Herd in the Henry Mountains of Utah.
It was originally founded with bison from the Yellowstone Park Bison Herd.
However, the extension of this herd into the Book Cliffs of Central Utah involved mixing the founders with additional bison from another source, so it is not known if the Book Cliff extension of the herd is also free of cattle hybridization.
A separate study by Wilson and Strobeck, published in Genome, was done to define the relationships between different herds of bison in the United States and Canada, and to determine whether the bison at Wood Buffalo National Park in Canada and the Yellowstone Park bison herd were possibly separate subspecies, and not Plains bison.
Some scientists had previously suggested that the Yellowstone bison were either of the "athabascae" (Wood bison) subspecies, or that they were a type of 'Mountain bison' subspecies.
It was determined by the study that the Wood Buffalo Park bison were actually cross breeds between Plains bison and Wood bison, but that their predominant genetic makeup was truly that of the expected "Wood Buffalo" (Bison bison athabascae).
However, the Yellowstone Park bison herd were pure Plains bison (Bison bison bison), and not any of the other previously suggested subspecies.
Since the Yellowstone Park herd are Plains bison, that would indicate that the Henry Mountain herd are also Plains bison.