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Black-tailed Deer (Odocoileus hemionus columbianus)

DSC_0471.jpegThe black tailed deer might not be super common throughout Lower Putah Creek, but spend some time at Lake Solano or in the inter-dam reach and you are sure to see plenty of deer jumping, running, or staring right at you. Black tailed deer are a subspecies of the mule deer that are found in northwestern United States including Northern California. These deer are distinguished by their entirely black tails all the way to their rump.

A drive up to our new headquarters nearby Lake Solano for a volunteer nursery day provides plenty of opportunity to see black tailed deer browsing around the hillsides and orchards. Often seen relaxing in the shade of trees or roaming by the water, black tailed deer prefer a small home range that provides for their needs in every season making Putah Creek a great place for roots! Deer are browsers and so they enjoy grasses, berries, oaks, and small underbrush for their food sources. Because they enjoy underbrush and grasslands, you won’t often see black tailed deer in densely forested areas unless they are escaping predators or the sun. They are even known to enjoy poison oak despite its irritating qualities!

November through early December is the mating season for black tailed deer. Does will often give birth to twins or even triplets in late spring (May and June) after a gestation period of around 210 days. Fawns are scentless for the first week of their lives allowing mothers to leave their young behind to replenish on food to produce enough milk for their young. Despite being excellent mothers, the mortality for black tailed deer is around 45 to 70% meaning does must be very protective of their fawns.The average lifespan of these deer are 9-10 years although some have been known to survive up to 17 years in captivity. Bucks grow their antlers starting in April and drop them after mating season between January and March. After mating, bucks often retreat and hide in order to rest and recuperate from any battle wounds from the mating season. 

Deer communicate through scent and pheromones from glands on the lower part of their legs. Through glands on the metatarsal part of their leg, they can secrete an alarm scent while the tarsal gland secretes pheromones that create a unique ID for mutual recognition. They even have glands between their toes and leave a scent behind as they walk! With excellent sight and hearing, deers use their independently moving ears to avoid predators and other dangers. 

Deer are most active at dawn and dusk and often browse for food under moonlight near roadsides particularly in wooded areas. Care should be taken when driving in such areas during dark as to avoid hitting them. Throughout California, there have been sporadic outbreaks of adenovirus hemorrhagic disease causing higher mortality in populations of black tailed deer. In order to prevent the spread of the disease, the California Department of Fish and Wildlife urges people to not feed, provide salt licks, water, or other attractants that would encourage grouping. 

If you’re looking for another reason to join our volunteer days out at our Native Plant Nursery, spotting a black tailed deer browsing in the surrounding hillsides is a great one!