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Dendragapus obscurusblue grouse

By Steven James

Geographic Range

Dusky grouse (Dendragapus obscurus) have a very large geographic range, extending from the Northwest Territories in northern Canada to northern New Mexico in the United States. They cover the western half of North America, living in the Rocky Mountains along with other neighboring mountainous areas such as the Black Hills in South Dakota, Wyoming, and Nebraska. This region covers an area of about 2,100,000 square kilometers, with a very large range of elevations. ("Colorado Parks and Wildlife", 2011; Barrowclough, et al., 2004; Bird and Symes, 2008)

Habitat

Dusky grouse live in a wide variety of environments, ranging from aspen mixed with sagebrush near sea level to dense areas of Douglas fir, lodgepole pine, and spruce at the tree line. They use these areas for different purposes throughout the year and migrate between them. During the summer months, these birds spend their time feeding in sub-alpine meadows or low lying areas rich with aspen, chokecherry, service berry, and oak brush. Along with grasshoppers, these plants are a prominent food source for dusky grouse this time of year. During the winter months, while most other animals found in mountainous areas have migrated to lower elevations, dusky grouse spend their time near the tree line at high elevations. They spend most of the winter roosting in Douglas fir and lodgepole pines feeding on the cones and needles these trees produce. These high elevation areas not only provide major food sources, but tend to have less predation during this time of year, as most predators follow the larger game animals to lower elevations. ("Colorado Parks and Wildlife", 2011; Bird and Symes, 2008; Fowle, 1960)

  • Range elevation
    0 to 3600 m
    0.00 to 11811.02 ft

Physical Description

Dusky grouse are exceeded in size only by sage grouse in North America, making them the second largest grouse on the continent. They can measure anywhere from 38 to 61 centimeters (12 to 15 inches) in length, with the males tending to be larger than the females. Males and females are hard to distinguish from one another at first glance. Upon close examination, males of this species are prominently slate grey mixed with white, whereas females are prominently greyish-brown mixed with white. Both sexes have a fan-shaped tail with a grey band running along the tip of the tail feathers. This band is most prominently evident in males, which fan their tail out during the spring mating season in the hopes of attracting a female. Dusky grouse have a prominent eye comb, especially during the spring time. The eye comb appears yellowish-orange on males and covers the entire upper half of their eye. The female eye comb only covers the upper inner top corner of the eye, and usually is dull yellow. Male grouse also have cervical sacks located bilaterally at the base of the neck, which can be filled with air as part of the mating ritual and are covered in white feathers. This distinguishes them from females, which lack these embellishments. ("Colorado Parks and Wildlife", 2011)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently
  • Range mass
    0.91 to 1.36 kg
    2.00 to 3.00 lb
  • Range length
    30 to 38 cm
    11.81 to 14.96 in
  • Range wingspan
    61 to 71 cm
    24.02 to 27.95 in
  • Average basal metabolic rate
    4.9570 W cm3.O2/g/hr

Reproduction

The mating behavior of dusky grouse takes place in the spring to mid-summer and is initiated by the hooting of males beginning in late March and continuing until mid-July. Males claim and defend a mating territory by fanning out their tail feathers, hoping, and clapping their wings. Dusky grouse are both lekking and non-lekking birds. This means the males either gather in a preferred area to challenge each other for females (lekking) or the males go out individually in search of females ready for mating. The males continue to hoot into the mid-summer months to try and attract females that have lost their clutch and are willing to mate again. ("Colorado Parks and Wildlife", 2011; Barrowclough, et al., 2004; Fowle, 1960; Martinka, 1970)

Once they breed, females find a downed tree or thick brush to provide protection for the nest they construct from grass and small twigs. Here they will lay an average of 7 to 9 eggs. The egg laying period fluctuates in different areas depending on the weather, but usually takes place in March. Research suggests after the eggs are laid they require an 18 to 21 day incubation period. Chicks begin to hatch in late May to early June. If a mother loses her clutch in early summer, she will often mate again with a willing male. ("Colorado Parks and Wildlife", 2011; Barrowclough, et al., 2004; Fowle, 1960; Martinka, 1970)

  • Breeding interval
    Dusky grouse breed 1 to 4 times yearly.
  • Breeding season
    Dusky grouse breed from early March to mid-July
  • Range eggs per season
    5 to 24
  • Range time to hatching
    12 to 14 days
  • Range fledging age
    12 to 24 hours
  • Range time to independence
    2 to 3 months
  • Average age at sexual or reproductive maturity (female)
    365 days
  • Average age at sexual or reproductive maturity (male)
    365 days

After the eggs have hatched, the chicks are protected from predators and intruders by their mother who will hiss and flap her wings to scare the intruder from the chicks. Male dusky grouse have no part in parental care. After the chicks have reached 10 to 28 days of age, the mother and her chicks begin to separate while feeding, but the mother can often be found perched over her chicks, keeping a watchful eye for intruders. By early autumn, the young stop following the mother and become independent, after which they begin grouping with other adults. ("Colorado Parks and Wildlife", 2011; Bird and Symes, 2008; Fowle, 1960)

  • Parental Investment
  • altricial
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents
  • inherits maternal/paternal territory

Lifespan/Longevity

Dusky grouse have a fairly short lifespan, with 50 percent of the birds lost in the first year. The birds that survive past the first year have an average lifespan of about three years. In areas with ample food and very low predation, birds have been known to survive up 14 years. (Redfield, 1975)

  • Range lifespan
    Status: wild
    1 to 14 years
  • Average lifespan
    Status: wild
    3 years
  • Typical lifespan
    Status: wild
    4 to 12 months

Behavior

Dusky grouse tend to stay in smaller groups during the warmer months and form larger flocks during the winter, when they spend most of their time in the tree tops eating needles and cones. In the summer months, the largest flocks are generally comprised of a female with her chicks, about 6 or 7 birds. During the winter, groups of 15 to 20 birds have been observed. This occurs because of the food and cover density during these times. In areas where food is not as plentiful, small groups can be unusual as many move to join larger groups when food becomes scarce. During the summer, these birds spread out through areas rich with resources, such as blueberry, chokecherry, or gooseberry bushes. ("Colorado Parks and Wildlife", 2011; Fowle, 1960; King and Bendell, 1982; Redfield, 1975; Schroeder, 2004)

Home Range

Dusky grouse move between alpine environments at the tree line where they spend their winters and down into lower lying areas high in food sources in the summer time. They tend to use the same areas year after year. The young birds follow their mother and continue to migrate between these areas as they get older. These birds usually travel short distances, but in some instances dusky grouse travel up to 30 miles between their summer and winter ranges. ("Colorado Parks and Wildlife", 2011; Fowle, 1960)

Communication and Perception

Dusky grouse communicate socially through a series of chirps and peeps throughout the year. These sounds are very subtle to the human ear and are hard to distinguish from other forest birds. They are used to alert each other to predators, and are particularly common between a mother and her young. If the mother and young get separated, the mother will call her young with a series of deep clucks that sound similar to the hoot males give during the breeding season. During the mating season, a male will use hooting to communicate with females. In association with the hoots, males clap their wings together, producing a loud series of thumps. This call is used to defend their territory and also to call females. ("Colorado Parks and Wildlife", 2011; Bird and Symes, 2008; Fowle, 1960)

Food Habits

Dusky grouse spend the winter months perched high in spruce, Douglas fir, and other conifer trees feeding on the needles and cones these trees produce. A favorite this time of year is the seed found in whitebark pine cones. It is high in protein and fats and provides these birds with a nutrient-rich diet that helps them through these cold months. During the summer months, dusky grouse feed on a variety of berries produced by blueberry, chokecherry, gooseberry, and huckleberry bushes. They also feed on a vast array of insects, especially grasshoppers. These birds rely on small gravel in their craw (a muscular organ located at the base of their neck) to grind up large foods. When the foods are ground enough to be digested, they pass into the stomach and intestines where the nutrients can be absorbed. (King and Bendell, 1982; Stewart, 1944)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit

Predation

Dusky grouse are a food source for many predators found in the surrounding areas. Coyotes, red foxes, Canada lynx, bobcats, mountain lions, grizzly bears, and black bears often take advantage of an opportunity to eat a dusky grouse if it arises. Other predators include American badgers, ermines, pine martens, hawks, and both golden and bald eagles. The best defense for dusky grouse is their camouflage and ability to fly. These abilities sometimes keep them from becoming prey but are not uniformly successful as dusky grouse are not very accomplished fliers. They are only able to fly in relatively short bursts compared to the aerial predators that pursue them, as such; camouflage is their best defense against raptors. Terrestrial predators have a much harder time catching dusky grouse. Many predators eat the eggs out of the nests, which are located on the ground. This gives dusky grouse a high mortality rate at a very young age. ("Colorado Parks and Wildlife", 2011; Fowle, 1960; Redfield, 1975)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Their major ecosystem roles include being an important food source for many predators. They also help control insect populations, such as grasshoppers, and disperse seeds from berry bushes throughout the ecosystem. In addition, dusky grouse may carry several parasites. ("Colorado Parks and Wildlife", 2011; Bendell, 1955)

  • Ecosystem Impact
  • disperses seeds
Commensal/Parasitic Species

Economic Importance for Humans: Positive

Dusky grouse are upland game birds that provide many hunters with a great opportunity to enjoy the mountainous areas they inhabit along with an appetizing meal for their dinner table. ("Colorado Parks and Wildlife", 2011)

Economic Importance for Humans: Negative

The only negative impact this species might have on humans is the spread of parasites from eating their meat. However, this is very uncommon and can be easily avoided through proper food handling and preparation. (King and Bendell, 1982)

Conservation Status

Dusky grouse have exhibited a very minor decrease in population over the last 40 years. There are an estimated 3,000,000 mature individuals in the wild, and the decrease is so small that the species is still listed as 'least concern' by the International Union for Conservation and Nature (IUCN). (Bird and Symes, 2008)

Other Comments

Dusky grouse are a recently identified species. The species formerly known as blue grouse (Dendragapus obscurus) was divided into dusky grouse (Dendragapus obscurus) and sooty grouse (Dendragapus fuliginosus) in 2006 based on DNA evidence. Sooty grouse live along the Pacific coast, from northern Canada to Southern California in the Sierra Madre Mountains. On the other hand, dusky grouse are found in inland North America, following the Rocky Mountains and other nearby montane regions. (Schroeder, 2004)

Contributors

Steven James (author), University of Wyoming, Hayley Lanier (editor), University of Wyoming - Casper, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

References

2011. "Colorado Parks and Wildlife" (On-line). Accessed November 13, 2013 at http://wildlife.state.co.us/Pages/Home.aspx.

Barrowclough, G., J. Growth, L. Mertz, R. Gutierrez. 2004. Phylogeographic structure, gene flow and species status in blue grouse (Dendragapus obscurus). Molecular Ecology, 13 Issue 7: 1911-1922.

Bendell, J. 1955. Disease as a control of a population of blue grouse. Canadian Journal of Zoology, 33: 195-223.

Bird, J., A. Symes. 2008. "Dusky Grouse (Dendragapus obscurus) Bird life international" (On-line). Birdlife.org. Accessed November 07, 2013 at http://www.birdlife.org/datazone/speciesfactsheet.php?id=32361.

Fowle, D. 1960. A study of blue grouse (Dendragapus obscurus Say) on Vancouver Island, British Columbia. Canadian Journal of Zoology, 38: 701-713.

King, D., J. Bendell. 1982. Foods selected by blue grouse (Dendragapus obscurus fuliginosus). Canadian Journal of Zoology, 60: 3268-3281.

Martinka, R. 1970. Structural characteristics and ecological relationships of male blue grouse (Dendragapus obscurus Say) territories in southwestern Montana. Canadian Journal of Zoology, Volume 38: 701-713.

Redfield, J. 1975. Comparative demography of increasing and stable populations of blue grouse (Dendragapus obscurus). Canadian Journal of Zoology, 53: 1-11.

Schroeder, M. 2004. Blue grouse (Dendragapus obscurus) are now considered to be two. Newsletter of Grouse Specialist Group, 32: 4-6. Accessed November 07, 2013 at http://wdfw.wa.gov/publications/01273/wdfw01273.pdf.

Stewart, R. 1944. Food habits of blue grouse. The Condor, 46: 112-120.

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