Columbia Black-tailed Deer – Crepuscular Cud Chewer 

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. 

 

California Department of Fish and Wildlife Twenty-five Year Dear Population Estimates

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)
Click image to purchase or see more Life on the Creek art
click image to download FREE coloring sheet

 

 

If you liked this post, you may also like Mountain Lion – Fragmented Power Pouncer.

 

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

 

Sierran Tree Frog with Chemical Sensitivities

Even though it has ‘tree’ in its name, the Sierran Tree Frog is mostly found near the ground.

Habitat

Tree frogs live in bushes and grass. Their preference is for damp, moist areas.

Behavior

Large toe pads that allow it to walk on vertical surfaces. The toe pads are also useful for clinging to sticks and twigs.

To avoid being eaten, the Sierran Tree Frog is fast! It can jump long distances and swim quickly to hide.  It also remains perfectly still and changes color to stay camouflaged. Sierran Tree Frogs can change from green and gray to brown.

The Sierran Tree Frog is more often heard than it is seen. Males call to advertise availability and attract mates. Breeding and egg-laying occur from November through July. During this time, males establish a territory that they defend with encounter calls, butting, or wrestling with rivals.

Diet

Worms, small invertebrates, and flying insects are the frog’s dietary staples.

Tadpoles feed on algae, bacteria and organic debris. Their feeding activities help keep streams and waterways clear of slippery plant material.

Global Amphibian Issues

Scientists say that we are living in the Anthropocene epoch, a time when human activity is the dominant influence on climate and the environment. Unfortunately, the consequences of this are that many habitats and species will disappear.

Frogs and newts are indicator species because they have thin skin that easily absorbs pollutants. Since they live both in water and on land, they absorb toxins from both environments. Like the miners who used canaries to warn when toxic gas was present, amphibian health determines the quality of the environment.

There are a number of factors that affect amphibian populations. Not unique to Nevada County, these conditions are happening globally.

Factors Contributing to Amphibian Decline

  • Housing and Habitat Loss

“We’re running out of places where frogs are healthy,” Amphibian Study Volunteer

“It doesn’t matter how many frogs we save if there is no place to put them back in the wild,” Edgardo Griffith, El Valle Amphibian Conservation Center

  • Chytridiomycosis (Batrachochytrim dendrobatidis) Skin Fungus – A Global Epidemic
  • Pesticide Runoff & Flushed Prescription Medications

California agriculture is the number one consumer of pesticides in the United States.

The state produces half of the US agricultural produce.

  • 99 percent of artichokes
  • 99 percent of walnuts
  • 97 percent of kiwis
  • 95 percent of garlic
  • 89 percent of cauliflower
  • 85% of the lettuce
  • 71 percent of spinach, and
  • 69 percent of carrots

Contaminated agricultural water runoff affects the entire ecosystem.

“Atrazine (an herbicide) is the most common contaminant in our drinking water. It causes male frogs to turn into females.” – Tyrone Hayes, UC Berkeley Biologist

  • Invasive Bullfrogs

“Bullfrogs pose several threats to the native amphibians of California, many of which are endangered. When bullfrogs—the largest frogs in North America—escape or are released into the wild, they have a tendency to eat other amphibians and any other wildlife that will fit in their mouths. Their size also allows them to outcompete native species for food. Even worse, a large portion of the bullfrogs imported into this country—62 percent according to one study—are infected with the deadly chytrid fungus (Batrachochytrium dendrobatidis), a lethal skin disease which has already been blamed for extinctions of about 100 amphibian species around the globe.” – Should California Ban American Bullfrogs? Scientific American Blog

 How to Help

Speak up for Nevada County frogs, toads, and salamanders.

 

If you liked this post, check out Miniscule Mountain Beetle Turning Forests Red

click on image to download free coloring sheet

click image to purchase or view more Life on the Creek art

Resources:

Books

Discovering Sierra Reptiles and Amphibians, Basey, H. E.

The Audubon Society Field Guide to North American Reptiles & Amphibians, Behler, J. L., King

Peterson Field Guide to Western Reptiles and Amphibians, Third Edition, Stebbins, R. C.

Websites

AmphibianWeb – Overview of Chytridiomycosis

California Tree Frog identification

Chytrid in Nevada County – Sierra Streams Institute

El Valle Amphibian Conservation Center

Frogs Need Our Help – amphibianfoundation.org

Hazards of Atrazine herbicide – Clear Health Centers video

Indicator Species – ecology.com

Nevada County Resource Conservation District – Amphibians

Reproductive problems linked to atrazine – Tyrone Hayes, UC Berkeley Biologist

Wildherps.com– Sierran Tree Frog

Service Working to Combat Killer Chytrid in California Frog Populations – Sacramento Fish & Wildlife Office

State of Sierra Frogs (2008) PDF – Sierra Nevada Alliance

Wildherps.com– Sierran Tree Frog

What if there is no happy ending? – Scientific American, 2013

Worldwide Amphibian Declines 2017

RSS
Follow by Email
LinkedIn
Share
Pinterest
fb-share-icon
Instagram