Tetrao urogalluswestern capercaillie

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. (Segel­bacher, et al., 2003; Storch, 2000; Wegge, et al., 2007)

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. (Storch, 2000; Wegge and Rol­stad, 2011)

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. (Storch, 2000)

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. (Wegge, et al., 2007)

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 (Lyru­rus 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. (EU Wildlife and Sus­tain­able Farm­ing Pro­ject, 2009)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently
  • male more colorful
  • ornamentation
  • Range mass
    3,902 to 6,500 g
    to oz
  • Average mass
    4,078 g
    oz
  • Range length
    60.96 to 86.36 cm
    24.00 to 34.00 in
  • Range wingspan
    87 to 125 cm
    34.25 to 49.21 in

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. (Johns­gard, 1983; Rol­stad, et al., 2007)

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. (Johns­gard, 1983)

  • Breeding interval
    Western capercaillies breed once yearly.
  • Breeding season
    The onset of male displays have been documented as early as January, the mating period ends in late May.
  • Range eggs per season
    5 to 12
  • Average eggs per season
    6.2-7.6
  • Range time to hatching
    24 to 26 days
  • Range fledging age
    2 to 3 months

Once mated, fe­males are left to raise their brood alone. Fe­males in­cu­bate, tend, and pro­tect their young until they reach in­de­pen­dence. (Johns­gard, 1983; Wegge, et al., 2007)

  • Parental Investment
  • 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. (AnAge, 2014; Robin­son, 2005)

  • Range lifespan
    Status: wild
    3.5 (high) years
  • Range lifespan
    Status: captivity
    18 (high) 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. (Johns­gard, 1983)

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. (Johns­gard, 1983)

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. (Johns­gard, 1983)

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. (Johns­gard, 1983; Storch, 2000)

  • 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. (Storch, 2000; Sum­mers, et al., 2004)

  • Anti-predator Adaptations
  • 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. (Storch, 2000; Sum­mers, et al., 2004)

  • 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. (Dun­smore and Poole, 2004)

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. (Dun­smore and Poole, 2004)

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. (Dun­smore and Poole, 2004; Storch, 2000)

Con­trib­u­tors

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

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

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.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

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.

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).

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.

polygynous

having more than one female as a mate at one time

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

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).

terrestrial

Living on the ground.

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

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.

Rol­stad, J., E. Rol­stad, P. Wegge. 2007. Ca­per­cail­lie Tetrao uro­gal­lus lek for­ma­tion in young for­est. Wildlife Bi­ol­ogy, 13 (Suppl.1): 59-67.

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.

Segel­bacher, G., S. Piert­ney. 2007. Phy­lo­geog­ra­phy of the Eu­ro­pean ca­per­cail­lie (Tetrao uro­gal­lus) and its im­pli­ca­tions for con­ser­va­tion. Jounal of Or­nithol­ogy, 148: 269-274.

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.

Thiel, D., C. Unger, M. Kéry, L. Jenni. 2007. of night roosts in win­ter by ca­per­cail­lie Tetrao uro­gal­lus in Cen­tral Eu­rope. Wildlife Bi­ol­ogy, 13 (Suppl.1): 73-86.

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.