Tetrao urogallus

Geographic Range

Tetrao urogallus (western capercaillies) have a Palearctic distribution. They are a non-migratory species, although hens with broods seem to use the same route to travel in search of high-quality insects for multiple years in succession. The northern boundary of their range reaches as far north as Scandinavia and continuously extends eastward into eastern Siberia. Further south in temperate Europe, western capercaillie populations occur in fragments. Prior to the second half of the 20th century, forestry practices and efforts to improve habitat lead to range expansion and high connectivity. During this time the connected habitats probably functioned as meta-populations. Western capercaillie populations are now declining in most of their central European range due to habitat deterioration and human disturbance.

• Biogeographic Regions
• palearctic palearctic
  • native native

Habitat

Western capercaillies live mainly in taiga and montane ecosystems. They prefer middle to late successional forests, but are not confined to old forests and have shown tolerance in the face of forest management regimes. Their habitats are characterized by the presence of coniferous trees with moderate canopy cover and ground vegetation rich with ericaceous shrubs, especially bilberry. In winter, western capercaillies almost exclusively feed on conifer needles. In the spring and summer their diet is supplemented with buds, flowers, leaves and shrubs.

Western capercaillies require large, contiguous areas of forested habitat. In the fragmented, temperate, region of central Europe, western capercaillies are exclusively found in montane regions.

Western capercaillie broods use late succession stage forests, often near peat bogs, and have been found to stay in natural forests rather than moving into pine plantations. Brood movements can be extensive, moving almost continuously in 24 hours in search of high-quality insects.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• taiga taiga
• mountains mountains

• Wetlands
• bog bog

Physical Description

Western capercaillies are large grouse that exhibit extreme sexual dimorphism. Males are the largest of the grouse family, ranging from 4 to 5 kg while females weigh no more than 2 kg. Males are distinguished by their dark black body color, iridescent blue and green, and vibrant red combs over the eye. Their fanlike tail is used for displaying to females. Female western capercaillies are similar to female black grouse ( Tetrao tetrix ), but are larger and have warmer brown coloration on her body. Females are distinguished by the rosy-rufous color on their throat, breast, and tail.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful
• ornamentation ornamentation

Reproduction

Western capercaillies are considered promiscuous and polygynous. Females show preference to dominant males on display grounds, and these males account for the majority of copulations amongst females. There is variation in the literature regarding the lekking habitat of western capercaillies. Leks are widely thought to be located in old forests. There are records of individual displaying areas being used for as long as one hundred years. On the other hand, a study by Rolstad and colleagues suggest that young forest stands (26 to 46 years) can be suitable for western capercaillie displaying activity. Mueller (1979 as cited in johnsgard 1983) found that, for fifteen years, a lek was occupied every spring and fall. In addition, some males occupied the same territories for as long as four years. His research suggests that the males who rank high amongst their peers gain respect for their territory. Interestingly, only the high-ranking males are allowed to copulate without disturbance. Males may hold this rank for several seasons and were observed performing more than 90% of total copulations in Mueller’s study. Once male capercaillies obtain a territory, they begin to advertise their fertility. There are three forms of advertisement including, tree display, flight display, and ground display. At the break of dawn, male western capercaillies begin their display by singing from their roost. The flight display is a noisy, drumming flight down from a perch. Variations of the flight display have also been noted; once on the ground a western capercaillie may perform “drumming jumps” in which he springs into the air and beats his wings. The ground display is performed with the “thinned-necked upright” posture with an extended “beard” and fanned tail. The wings are held downward flashing the white shoulder patches. Territory defense includes ritualized confrontations that may lead to intense fights. Rival males may begin with a “display flight” with the two males bill-to-bill. Neck feathers become increasingly ruffled and the males may perform the “belching cantus.” As the confrontation becomes more intense, pecking and blows are exchanged. Although most observed fights seem to end inconclusively, if there is a true victor, the losing grouse retreats.

• Mating System
• polygynous polygynous
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Male western capercaillies gather at traditional display grounds. The onset of display varies in different areas of their range. Territory occupation has been documented as early as January and seems to end near the onset of molt in adult males. Usually, nesting sites are not far from lekking grounds and are often times clumped. After mating, females are left to incubate young on their own in shallow scrapes. Scrapes are often created at the base of trees under thick cover. Anywhere from 5 to 12 eggs are laid, a complete clutch takes about 10 days to lay. After the last egg is laid the female incubates her clutch about 25 days. During incubation the female only leaves the nest to feed, usually once in the morning and once late afternoon. Western capercaillies exhibit synchronous hatching. After hatching, the chicks soon leave the nest to feed, during this time the hen acts as a sentinel and keeps her brood close. Brood movements are nearly continuous, interspersed with intense foraging in “hot-spots.” Short flight is observed when broods are 2 to 3 weeks. The chicks fledge at 2 to 3 months old.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Once mated, females are left to raise their brood alone. Females incubate, tend, and protect their young until they reach independence.

• Parental Investment
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Typical lifespan of western capercaillies is unreported in the literature, but in the U.K. one wild individual lived to 3.5 years and a captive individual was recorded living to 18 years.

Behavior

Western capercaillies can be very mobile, yearling males have been reported traveling up to 7 km in a day visiting leks. Once broods have fledged, females and yearlings travel and forage in loose flocks while adult males remain solitary. They forage on the ground and in trees. Males often forage in areas 3 to 4 m below the apex of trees.

• Key Behaviors
• terricolous
• flies
• glides
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social

Home Range

Home range sizes of western capercaillies are not reported in the literature, but they are capable of moving over large areas in search of food and mating opportunities.

Communication and Perception

Probably the most fascinating communication center of western capercaillies is the lekking grounds. Male displays take three distinct forms including tree display, flight display, and ground display. The tree display is exclusively vocal, the song includes a metallic "gulping" sound accompanied by "clicking" sounds. During the tree display, capercaillies assume an upright posture holding their tail low. The flight display includes a loud flight down from a tree to the ground. The flight down is accompanied by noisy wing drumming and vocal rattles. Once on the ground capercaillies continue to make short vertical flights into the air known as "drumming flights." Ground displays are performed in a "thin-necked up right" posture. The neck is stretched and the head held upward so that the beard (a thick patch of chin feathers) is protruding. The wings are held lowered exposing the white shoulder patch. The song of western capercaillies, also called the "canto," is categorized into four phases. The first phase consists of a series of doubled-noted clicks, the bill is opened on the first and closes on the second. The tempo increases until the clicks merge into a roll and ends in a "cork note" (the sound is similar to that when a cork is popped from a bottle). The canto is completed when the bird utters 3 to 5 notes that have been described as a scythe being whetted.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Western capercaillies depend on pine most of the year, although food habits change seasonally. In the winter they depend on pines, primarily Scots pine ( Pinus silvestris ). They may also feed on the needles and berries of juniper ( Juniperus commuis ) sparingly. In the spring and summer their diet expands to include leaves, stems, mosses and berries; bilberry becomes an important food plant. Western capercaillies younger than 20 days have been observed feeding on invertebrates, including spiders, ants and, beetles.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Animal Foods
• insects
• terrestrial non-insect arthropods

• Plant Foods
• leaves
• wood, bark, or stems
• seeds, grains, and nuts
• fruit
• flowers
• bryophytes

Predation

The main predators of western capercaillies include carrion crows ( Corvus corone ), red foxes ( Vulpes vulpes ) and raptors . Although pine martens ( Martes martes ) have been documented feeding on western capercaillie eggs, their abundance does not seem to significantly affect breeding success. Western capercaillie females, and most female grouse , have cryptic plumage that blends into ground and shrub vegetation. Females and juvenile males are mottled and barred with dull white, black and buff. This cryptic plumage pattern aids in their ability to remain undetected by predators.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Western capercaillies, like many ground nesting birds, fall victim to egg predation. Common nest predators include crows, foxes, raptors, and martens. They sparingly feed on juniper and other berries, and therefore may aid in seed dispersal, however, there is no evidence that this dispersal is significant.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Historically, western capercaillies have been of hunting and cultural importance across their range. Being the largest grouse species, they have been highly valued as hunting trophies in central Europe. Since the 1700’s, there have been times when western capercaillie hunts were reserved for the patricians. According to the Capercaillie Life Project, they have traditionally been hunted in their spring lek. Highest ranking cocks were preferred hunting trophies. Research testing the affects of spring and autumn hunts on populations are needed. In addition to their economic benefit as a game species, western capercaillies are enjoyed by bird-watchers and naturalists who may engage in ecotourist activities to see these, and other, European birds.

• Positive Impacts
• food food
• ecotourism ecotourism
• research and education

Economic Importance for Humans: Negative

Large, late succession forests seem to be favored by western capercaillie populations. These forests are often cleared for farm land or lumber. If maintaining these forests for western capercaillie populations provide profits lower than that of farms or lumber, there is potential for a negative economic effect.

Conservation Status

In 1785 over-hunting and land mismanagement caused western capercaillie populations be extirpated in Scotland. A Swedish stock of western capercaillie were reintroduced in 1837, but numbers declined to around 1,000 birds in 1999. Western capercaillie are still located throughout most of their Palearctic distribution, but serious declines in western and central Europe have resulted in local extinctions. In the southern reaches of the range, they are found almost exclusively in montane regions. Some major causes of population decline include deer fences, which cause large mortalities from collisions, predation, habitat fragmentation and loss. Western capercaillie require large areas of contiguous forest and chicks are more sensitive to habitat changes than adults and require higher quality habitat. The forest areas that best support western capercaillies also benefit many other native species. For these reasons, they are often thought of as indicator, or umbrella species. Conservation efforts that target western capercaillie will likely benefit an array of native species.

Additional Links

Encyclopedia of Life

Contributors

Laurel Hill (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

AnAge, 2014. "Tetrao urogallus" (On-line). AnAge: The Animal Ageing and Longevity Database. Accessed February 26, 2014 at http://genomics.senescence.info/species/entry.php?species=Tetrao_urogallus .

Bajc, M., M. Cas, D. Ballian, S. Kunovac, G. Zubic, M. Grubesic, P. Zhelev, L. Paule, T. Grebenc, H. Kraigher. 2011. Genetic differentiation of the western capercaillie highlights the importance of south-eastern Europe for understanding the species phylogeography. PLoS ONE , 6: e23602.

Butchart, S., J. Eckstrom, A. Symes. 2010. "LC Western Capercaillie Tetrao urogallus " (On-line). Birdlife International. Accessed February 14, 2013 at http://www.birdlife.org/datazone/speciesfactsheet.php?id=295 .

Catt, D., D. Baines, N. Picozzi, R. Moss. 1998. Abundance and distribution of capercaillie Tetrao urogallus in Scotland 1992-1994. Biological Conservation , 85: 257-267.

Dunsmore, J., T. Poole. 2004. "The Bird" (On-line). Capercaillie Life Project. Accessed March 01, 2013 at http://www.capercaillie-life.info/index.php .

EU Wildlife and Sustainable Farming Project, 2009. "Capercaillie Tetrao urogallus Fact Sheet" (On-line pdf). Accessed February 13, 2012 at http://ec.europa.eu/environment/nature/natura2000/management/docs/Tetrao%20urugallus%20factsheet%20-%20SWIFI.pdf .

Johnsgard, P. 1983. The Grouse of the World . United States of America: University of Nebraska Press.

Picozzi, N., D. Catt, R. Moss. 1992. Evaluation of capercaillie habitat. Journal of Applied Ecology , 29: 751-762.

Robinson, R. 2005. "Capercaillie Tetrao urogallus [Linnaeus, 1758]" (On-line). BirdFacts: profiles of birds occurring in Britain & Ireland (BTO Research Report 407).. Accessed February 26, 2014 at http://blx1.bto.org/birdfacts/results/bob3350.htm .

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Segelbacher, G., J. Höglund, I. Storch. 2003. From connectivity to isolation: genetic consequences of population fragmentation in capercaillie across Europe. Molecular Ecology , 12: 1773-1780.

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Storch, I. 2000. Grouse . IUCN, Gland, Switzerland and Cambridge, UK and The World Pheasant Association, Reading, UK: IUCN Publications Service Unit.

Storch, I. 1995. Annual Home Ranges and Spacing Patterns of the Capercaillie in Central Europe. The Journal of Wildlife Management , 59/2: 392-400.

Storch, I. 2002. On Spatial Resolution in Habitat Models: Can Small-scale Forest Structure Explain Capercaillie Numbers?. Ecology and Society , 6/1: 6. Accessed February 14, 2013 at http://www.ecologyandsociety.org/vol6/iss1/art6/ .

Summers, R., R. Green, R. Proctor, D. Dugan, D. Lambie, R. Moncrieff, R. Moss, D. Baines. 2004. An Experimental Study of the Effects of Predation on the Breeding Productivity of Capercaillie and Black Grouse. Journal of Applied Ecology , 41: 3.

Thiel, D., E. Menoni, J. Brenot. 2007. Effects of recreation and hunting on flushing distance of capercaillie. The Journal of Wildlife Management , 71: 1784-1792.

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Wegge, P., M. Finne, J. Rolstad. 2007. GPS satellite telemetry provides new insight into capercaillie Tetrao urogallus brood movements. Wildlife Biology , 13 (Suppl.1): 87-94.

Wegge, P., J. Rolstad. 2011. Clearcutting forestry and Eurasian boreal forest grouse: Long-term monitoring of sympatric capercaillie Tetrao urogallus and black grouse T. tetrix reveals unexpected effects on their population performances. Forest Ecology and Management , 261: 1520-1529.