Due to the eradication of the Mule Deer herd on Santa Rosa Island, which took place in 2011, the Catalina Island Mule Deer is now the only known Island Mule Deer herd remaining in California. The Catalina Island Mule deer is a unique herd as a result of its genetic history. The original mule deer were introduced to the Island in 1928. Three deer came from Modoc County in northern California and then 19 deer were brought to the Island a few years later from Los Angeles County.
The environment of Catalina Island has some very unique attributes when compared to the common Mule Deer habitat. Although the topography is similar with deep canyons and fairly tough terrain, the winters are relatively mild with no snow or extreme cold temperatures. These environmental conditions provide for ideal conditions for the deer to not only exist but to thrive. The only limiting factor is the lack of adequate rainfall during the winter rainy season. Unlike the larger Rocky Mountain Mule Deer found in the west, the Catalina Island mule deer body size is comparable to those of the coastal blacktail. A unique feature of a good number of Catalina bucks are the dark chocolate colored antlers. The exact reason for the dark color has not been determined; it could be genetics, environment or both. For whatever the reason, these bucks are truly a unique and sought after trophy to have on the wall.