The Columbian black-tailed deer (Odocoileus hemionus columbianus) has a geographic range that spans from southern British Columbia to Santa Barbara County in California, and as far east as the Cascade and Southern Sierra Nevada Mountains. The species is commonly found throughout Point Reyes National Seashore, in the forests of Muir Woods, as well as coastal scrub and agricultural fields throughout the region. Black-tailed deer are considered a “keystone” species in the native California coastal ecosystem because fluctuations in their population numbers have the potential for repercussions throughout the ecosystem.
Non-native deer have also been introduced into Point Reyes National Seashore in the past, and in many places their populations have grown and spread. Scientists are concerned about the effects these species may have on black-tailed deer populations, along with the rest of the ecosystem. As a result, biologists have developed theoretical models predicting the effect of non-native deer on black-tailed deer populations. Increased competition with non-native deer for food is likely to result in decreased food availability for black-tails, and the presence of non-native deer may also increase risk of transmission of certain diseases between these species. These factors, in combination with various other circumstances, could significantly reduce black-tailed deer numbers.