Antelope Island holds populations of pronghorn, bighorn sheep, American bison, porcupine, badger, coyote, bobcat, mule deer, and millions of waterfowl.

The geology of Antelope Island consists mostly of alluvial plains with prairie grassland on the north, east and south of the island, along with a mountainous central area of older Precambrian metamorphic and igneous rocks and late Precambrian to Paleozoic sedimentary rocks, covered by a thin layer of Quaternary lake deposits, colluvium and alluvium.

Originally, Antelope Island was used as a ranch for cattle and sheep, starting from the earliest days of the arrival of the Mormon pioneers into the Salt Lake Valley.

[11][12] In February 2024, the Miller family foundation announced a $2.2 million donation to support water conservation efforts through the Antelope Island Learning Center.

Paleolithic people lived near the Great Basin's wetlands, which had an abundance of fish, birds, and small game animals.

Big game, including giant bison, mammoths and ground sloths, were also attracted to the water sources.

Relying more on gathering than the previous Utah residents, their diet was largely made of cattails and other salt tolerant plants such as pickleweed, burro weed and sedge.

The Desert Archaic people used nets and the atlatl to hunt water fowl, small animals and pronghorns.

About 3,500 years ago, lake levels rose and the population of Desert Archaic people appears to have dramatically decreased.

[16] Historians speculate that Dooly introduced the herd to the island for commercial purposes with the idea of establishing a rare opportunity for hunters to take the nearly extinct American bison.

[20][16] The last herds of cattle were removed from the island in 1984 after an extremely snowy winter that caused the death by starvation of about 350 heifers and calves.

[23] The study had high praise for Antelope Island as a potential national park, but found "little else worthwhile about the Great Salt Lake".

The National Park Service was concerned with a lack of planning by the State of Utah and the fact that the lake was used as a dumping site for municipal and industrial waste.

[24] In 1971 the directors of the Golden Spike Empire, Inc., a local civic group that sought to promote the Great Salt Lake area as a tourist destination, recommended that all of Antelope Island be purchased.

The local government was in favor of the state park and encouraged its development as a means of attracting tourists and increasing county revenues.

The inland grasslands on the island provide habitat for chukars, burrowing owls, long-billed curlews and several species of birds of prey.

Biologists estimate that as many as 60 million bison roamed the western United States prior to the lands being settled by Anglo Americans.

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.

[41] However, due to the lack of a natural predator, the gray wolf,[17] the bison thrived on the island and the herd rapidly increased in size.

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.

The animals are worthless — there isn't worse meat on Earth to eat — and they ruin the whole territory for cattle grazing purposes.

Governor Dern declined to prevent the hunt stating, "Antelope Island and the buffalo herd are privately owned.

"[22] 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 first roundup was held in 1987[40] 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.

[17][40] Every year, in late October, all the bison on the island are herded to a central area in a "Great Buffalo Roundup" and sent briefly into pens where they are examined, weighed and vaccinated, whereupon decisions are made on culling and selecting breeding stock.

Some bison are also purchased at the pen site in a yearly public auction, and are taken as meat or breeding stock for commercial farms in other parts of the world.

[45] Biologists at the park and with the state of Utah felt that Antelope Island would be an "ideal oasis" for establishing a "nursery herd" of bighorn.

[18][33] The lake and surrounding wetlands are home to over 250 species of birds and form a stop over on the Pacific Flyway between South and North America.

A large population of black-necked stilts, American avocets and newborn pelicans are also found on and near the Great Salt Lake.

Along the shoreline of the island, mallard, Canada goose, avocets, black-necked stilts, willets, long-billed curlews, sanderlings, American white pelicans, pied-billed grebes, killdeer, great blue herons, snowy egrets, white-faced ibis and many migratory birds can be observed.