nature

Antelope Island

Antelope Island is the largest of all the islands in the Great Salt Lake in the U.S. state of Utah. The lake is fed by the Bear, Weber and Jordan rivers and has no outlet. Its size varies greatly depending on the evaporation rate and the flow of the three rivers that feed it. And so it is not very surprising that in the early and mid-19th century, when the water level was low, it was easier for the first explorers and researchers to cross the large inland lake and reach the island. In 1845, the U.S. explorer John Charles Frémont wrote: “There is at this southern end of the lake a large peninsular island which the Indians informed me could at this low stage of the water be reached on horseback. Accordingly … I took with me (Kit) Carson and a few men and rode across the shallows.“

The island owes its protection and seclusion primarily to salt. The tributaries of the Bear, Weber and Jordan rivers discharge more than 1.1 million tons of salt annually into the Great Salt Lake. This high salt content makes the lake itself almost uninhabitable. Only a few life forms, such as the brine shrimp, brave this hostile biotope. On the other hand, the surrounding marshes and saline alluvium are habitat and food source for halophilic plants and several water birds. These include pelicans, herons, cormorants, terns and gulls. Small and large wading birds, divers and ducks can also be identified with the help of informative panels. Another panel provides information on the feeding cycle of brine flies. The population of this salt or marsh fly grows to an astonishing density in the presence of an abundance of algae (under and above water), and – often suspended in black ribbon-like formations – provides the food base for local waterfowl.

In the course of its discovery, human intervention in the nature of the island increased rapidly. Thus, Frémont continued in his execution: “On the island we found grass and water and several bands of antelope. Some of these were killed, and in memory of the grateful supply of food they furnished, I gave their name to the island.“
The antelope named by Frémont were pronghorn antelope. Two of these pronghorns served as meals for the island pioneers and subsequently became the namesakes of the island. However, this was both the discovery and the decline of the native pronghorn. For by 1930 the antelope had completely disappeared from the island. It was not until 1933 that 24 pronghorn antelope were reintroduced to the island, and their population nearly doubled in the following two years.

Until 1847, Antelope Island was primarily covered with native plants. However, when the land was grazed for cattle and sheep the following year, not only were livestock and seeds introduced, but also quite a few plant species, some of which are now considered harmful in Utah. For example, 150 years of permanent livestock and overgrazing caused plants and trees such as desert mugwort and Fremont cottonwood to give way to invasive thistles, forbs, grasses, and flowers.

A few California bighorn sheep were introduced in March 1997 and have intermediately multiplied to a total of 200. After many animals became infected with a fatal respiratory disease, the entire herd on Antelope Island had to be completely culled. This was followed by repopulation with 25 bighorn sheep, which were to be protected from a new outbreak of the disease by observation and fencing.

On 15 February 1893, 12 bison were brought to the island by sailboat. By the 1930s, the once small herd had grown to over 500 animals and is now regulated by humans to keep them compatible with the island's vegetation. When the young are born in the spring, the base of the herd can grow to over 700 animals. At the end of October, all the animals on the island are rounded up, examined and vaccinated. Surplus animals are sorted out in the course of this for auctions, in order to achieve again the basic stock.
Today, Antelope Island is considered a refuge for bison and other wildlife – the island's eastern slope, for example, offers a widely available area inaccessible to humans that ensures protection and seclusion for the animals.

Although the history of Antelope Island has been strongly influenced by man, it also bears witness to the natural richness and coexistence of the most diverse forms of life, which have not only adapted to each other but also to the circumstances surrounding them. On an area of a good 115 km², native and neobiotic, interconnected plants and animals can be found here in a unique biological community that – today as then – is worth discovering.

USA, May 2022. | All words and photos by The Sturgheons.