The American Bison (Bison bison) is the largest terrestrial mammal in North America, often strongly associated with the vast, open Great Plains. While the species is an icon of the central United States, its historical range was much broader, stretching from Alaska down into Mexico and from the eastern forests to parts of the western mountains. Given this expansive natural history, many people wonder if California, with its diverse habitats, still hosts these massive grazers. Bison do live within the state, though not in truly native or unmanaged populations, existing as a complex story of conservation, cinematic history, and careful management.
Current Status of Bison Populations in California
Bison populations in California today are entirely the result of introduction and subsequent management, existing in two distinct categories. The first category includes small herds allowed to roam freely within very large, non-fenced tracts of land, such as an island or a military installation. These herds are actively managed to control population size, health, and genetic diversity.
The second, more common category involves contained herds maintained for conservation, exhibition, or public education within fenced paddocks in metropolitan parks or specialized reserves. These herds are often small and intensively managed by municipal or non-profit organizations. There are no truly wild, native, or unmanaged bison populations remaining in California, as the species was extirpated from the state during the 19th-century slaughter.
The Unique Catalina Island Herd
The most famous bison population in the state resides on Santa Catalina Island, approximately 22 miles off the coast of Southern California. The herd was established in 1924 when a small group of 14 to 24 bison were brought to the island for a silent film production. When the production left, the animals were simply abandoned, and the population began to grow over the following decades.
The bison are not native to the island ecosystem, which did not evolve with large grazing ungulates, leading to concerns about their impact on endemic flora. The Santa Catalina Island Conservancy, which manages 88% of the island, actively works to manage the herd size to protect the native environment. The population peaked at over 520 individuals in 1987, requiring the Conservancy to implement control measures.
Since 1969, thousands of bison have been captured and exported to the mainland, often sent to Native American reservations or private ranches to reduce the ecological strain on the island. More recently, the Conservancy has employed immunocontraception, specifically the Porcine Zona Pellucida (PZP) vaccine, to control reproduction and maintain the herd at a sustainable size, typically targeting 150 animals or less. This management approach has been successful in limiting births, representing a humane alternative to continuous culling or export.
State and Private Managed Conservation Herds
Beyond Catalina Island, a second notable population considered “wild-roaming” within a contained area is the herd at the Marine Corps Base Camp Pendleton in San Diego County. This herd was established between 1973 and 1978 when a dozen Plains Bison were donated by the San Diego Zoo. The animals roam within a large, undeveloped 125,000-acre section of the military base, which offers abundant forage and water sources.
The Camp Pendleton Game Warden’s Office monitors the herd, which typically numbers around 90 to 150 individuals, for overall health and genetic diversity. Although they roam freely across the large expanse of the base, their movement is contained by the installation’s perimeter, and their presence sometimes requires the adjustment of military training exercises.
A contrasting example of a contained population is the historic herd in San Francisco’s Golden Gate Park. This urban herd was established in 1891 by Park Superintendent John McLaren as an early conservation effort to save the species from total collapse. The herd is housed in a fenced paddock, the Bison Paddock, and is now managed by the San Francisco Zoo and the city’s Recreation and Park Department. To prevent territorial aggression, the Golden Gate Park population currently consists only of female bison.
Extinction and Reintroduction History
The American Bison’s historical range included the Great Plains subspecies, whose western extent reached into the northeastern part of California. They were never established in the coastal or southern regions of the state, nor in the Central Valley, unlike their Pleistocene ancestors, which died out about 10,000 years ago. By the late 19th century, the relentless hunting campaign across North America had driven the species to near-extinction, with fewer than 1,000 individuals remaining.
This population collapse spurred a conservation movement that led to the establishment of the first managed herds in the early 20th century. The introduction of bison to places like Golden Gate Park in 1891, and later to Catalina Island and Camp Pendleton, was a direct response to this crisis, intending to preserve the species’ genetics and numbers. All bison found in California today are descendants of these introduced herds, serving as living legacies of one of the country’s most successful conservation stories.