From the Catalina Island Conservancy's website: "The bison were introduced to Catalina. Fourteen head were brought to the Island in the 1920s for the making of a film. Over the last 85 plus years of residence on the Island, bison have become an expected feature, almost iconic, to the Island traveler. A number of tours, literature and attractions feature the bison, which have become rather famous. In 2003, the Conservancy commissioned a scientific study of the bison and their impact on the Island. According to the study, the bison suffer from a poor diet due to frequent drought conditions and a history of overgrazing by other non-native herbivores.
The study also found that the animals are significantly smaller than mainland bison, and appear in relatively poor nutritional condition.The study additionally concluded that while a large, unrestricted herd of bison can be detrimental to some of the more fragile native habitats, a small herd (between 150 and 200 animals) restricted to certain areas of the Island could be sustained without causing undue stress to native plant communities. The Conservancy is sensitive to the wants and needs of the resident community, and has adopted this strategy. The Conservancy is committed to maintaining a herd of between 150 and 200 animals, the number determined through a scientific study to be optimum for keeping both the herd and the Island ecosystem healthy."