The word ‘deer’ is an irregular noun. It is used for both single and multiple animals. Deer are also crepuscular, active during twilight hours.
Of the six subspecies of mule deer living in California, Nevada County is home to two; the California mule deer (west side of Sierra Nevadas to the southern coast) and the Columbia black-tailed deer (Northern California through the Pacific Northwest). Since black-tailed deer are the species roaming through my yard, they are the main subject of this article.
History & Range
The Columbia black-tailed deer is also known by the names; Pacific buck, Columbian deer, coast black-tailed buck, and black-tailed deer. It is a subspecies of Mule deer and will cross-breed with the California mule deer and Rocky Mountain mule deer where habitats overlap.
In 1846, an Oregon Trail traveler noted black-tailed deer as far west as Wyoming. Today their range is smaller. It includes northern California, Oregon, Washington, some parts of coastal and interior BC as well as the Alaskan panhandle.
With the 1934 Taylor Grazing Act, the organization that eventually became known as the Bureau of Land Management was tasked with managing public forage lands for cattle and wildlife. It became one of the numerous organizations cooperating across state and county lines to track and manage these wild animals. ( US Forest Service, California Department of Fish and Wildlife and U.S. Department of Agriculture.)
Identification
- large ears, relaxed
- short, stubby tail
- loose tail position
- winter coat color – silver gray
- cap / patch of fur at top of head
- thicker stripe of dark fir on tail than Mule deer
Behavior
Except for breeding season (November – December), does and bucks live in separate groups.
Female groups of related individuals are led by a dominant (alpha) animal, usually the eldest mother. She chooses foraging and birthing grounds. The alpha female is usually the first to mate during mating season and she generally chooses to stay close to her mother’s territory, leaving it only if forced.
Males leave their mothers between a year-and-a-half and eighteen months old to seek bachelor groups.
New antlers (bone protrusions) are grown each spring and shed every winter.
Antlers are grown out with a ‘velvet’ covering, a living structure with blood vessels. Once it dries and antlers harden, bucks rub them against trees to remove the velvet. A buck’s age is reflected in the number of forks. Antlers are used for sparring and determining social position as well as for mate competition.
Communication
Communication methods include vocalizations, scent, and pheromones. Glands between the toes, and near the knees (hock) create trail marking and individual recognition signals while glands outside the lower legs produce alarm scents.
Large, independently moving, ears enable sensitive hearing.
Migration
In California, at higher elevations, some herds of black-tailed deer migrate. Locations of forage food and snow levels determine their movements.
In Nevada County, below Nevada City, seasonal herd movements do not cover great distances.
Life Span
The black-tailed deer life span is approximately 7 years (in the wild), reaching sexual maturity between 1-2 years.
Reproduction
Males are polygynous, they’ll mate with multiple females.
Female gestation lasts between six to seven months, with fawns born May – June.
For the first week after birth, fawns have no scent. This allows the mother to leave her babies to replenish her body weight and produce adequate amounts of milk for her young.
Caution: Mothers with fawns view humans as predators.
Diet
Like cattle, sheep, giraffe, goats, and antelope, deer are cud-chewing grazers. With teeth and mouthparts specialized for breaking down cellulose as well as a digestive compartment housing bacteria necessary to turn plant material into protein, volatile fatty acids as well as vitamins B and K, deer spend the early morning and dusk hours grazing and afternoon and evening hours, bedded down, regurgitating, and giving food a second chew.
Spring and winter diet includes;
- California Buckeye
- Douglas-fir
- Fern
- Lichen
- Huckleberry
- Poison oak
- Grasses
- Cedar
- Bark & buds
Late spring and fall diet includes;
- Grasses
- Fruit (blackberry & apple)
- Fireweed
- Pearly everlasting
- Forbs
- Rosehips
- Salmonberry
- Salal
- Maple trees
- Acorns
Rumination – Chewing Cud
Grazer gut bacteria often match soil microbes. Eating and defecating perpetuate healthy regeneration cycles for both plants and animals.
Grazing to Heal the Earth – Grasses & Ruminants | 3:14 Chewing Cud
Predators
- Mountain lion
- Coyote
- Eagle
- Bear
- Humans
Deer Hunting Industry & Income Generation
In California, Deer hunting permit sales generate around $450 million dollars annually, attracting between 165 – 200K hunters.
Issues Affecting Deer Habitat & Populations
- Habitat loss & fragmentation
- Herbicide use on private and public lands
- Timber & reforestation practices – biomass, hardwood removal, clear-cutting & thinning
- Livestock grazing
- Prescribed fire & fire suppression & wildfires
- Reservoirs
- Ski areas, golf courses & agricultural land uses
- Poaching
- Changing weather patterns including severe winters and drought
- Highways and roads (1.5 million deer and vehicle collisions/year – Insurance Institute for Highway Safety)
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Resources:
Bay Nature – Are Deer Twins Common?
California Department of Fish and Game – Assessment of Mule and Black-tailed Deer Habitats and Populations in California – 1998 [PDF]
California Department of Fish and Wildlife – Mule Deer
California Department of Fish and Wildlife – Deer Management Documentation
California Department of Fish and Wildlife – Deer Population Estimates
California Department of Fish and Wildlife – Private Lands Management
iNaturalist – Columbian Black-tailed Deer
Journal of Wildlife Disease – Hair-Loss Syndrome in Black-tailed Deer of the Pacific Northwest
Mule Deer Foundation
Mississippi State University | Deer Ecology & Management Lab – Antler Growth Cycle
National Park Service – Pacific Coast Science and Learning Center – Black-tailed Deer Researchers, References & Links
Sierra Club – Largest Mule Deer Migration Ever Recorded
Western Hunter – Black-tailed deer of California
Wikipedia – Ruminants
Mule Deer Migrations
Nevada & Texas Deer Herd Management
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