View source for Western capercaillie

{{short description|Species of bird}}
{{Speciesbox
| image = Capercaillie (8751340764).jpg
| image_caption = Male (cock)
| image2 = Tetrao urogallus - Eurasian Capercaille - Tjäder.jpg
| image2_caption = Female (hen)
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn">{{cite iucn |author=BirdLife International. |year=2024 |title=''Tetrao urogallus'' |volume=2024 |article-number=e.T22679487A264563031 |doi=10.2305/IUCN.UK.2024-2.RLTS.T22679487A264563031.en |access-date=8 August 2025}}</ref>
| genus = Tetrao
| species = urogallus
| authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| range_map = Western Capercaillie Tetrao urogallus distribution map.png
| range_map_caption = Range of the western capercaillie<ref name="iucn"/>
| range_map2 = Western Capercaillie Tetrao urogallus distribution in Europe map.png
| range_map2_caption = Distribution in Europe<ref name="IUCN_Eur">{{cite iucn |author=BirdLife International. |year=2021 |title=''Tetrao urogallus'' (Europe assessment) |volume=2021 |article-number=e.T22679487A166188330 |doi=10.2305/IUCN.UK.2021-3.RLTS.T22679487A166188330.en |access-date=8 August 2025}}</ref> 
}}

The '''western capercaillie''' ('''''Tetrao urogallus'''''), also known as the '''Eurasian capercaillie''', '''wood grouse''', '''heather cock''', '''cock-of-the-woods''', or simply '''capercaillie''' {{IPAc-en|ˌ|k|æ|p|ɚ|ˈ|k|eɪ|l|(|j|)|i}},<ref name="CEPD">{{Citation
|last=Roach
|first=Peter
|year=2011
|title=Cambridge English Pronouncing Dictionary
|edition=18th
|place=Cambridge
|publisher=Cambridge University Press
|isbn=978-0-521-15253-2
}}</ref> is a heavy member of the [[grouse]] tribe and the largest of all extant grouse species. Found across Europe and the [[Palearctic]], this primarily-ground-dwelling forest grouse is renowned for its courtship display. The bird shows extreme [[sexual dimorphism]], with males nearly twice the size of females. The global population is listed as "least concern" under the IUCN,<ref name="iucn" /> although the populations of central Europe are declining and fragmented, or possibly [[wikt:extirpate|extirpated]].

The western capercaillie is one of two living species under the genus ''[[Tetrao]]'', which also includes the lesser-known [[black-billed capercaillie]].

==Taxonomy==
The western capercaillie was [[Species description|formally described]] in 1758 by the Swedish naturalist [[Carl Linnaeus]] in the [[10th edition of Systema Naturae|tenth edition]] of his ''[[Systema Naturae]]'' under its current [[binomial nomenclature|binomial name]] ''Tetrao urogallus''. Linnaeus specified the [[type locality (biology)|type locality]] as Europe but this is now restricted to Sweden.<ref>{{cite book | last=Linnaeus | first=Carl | author-link=Carl Linnaeus | year=1758 | title= Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis | volume=1 | edition=10th | page=159 | publisher=Laurentii Salvii | location=Holmiae (Stockholm) | language=Latin | url=https://www.biodiversitylibrary.org/page/727066 }}</ref><ref>{{ cite book | editor-last=Peters | editor-first=James Lee | editor-link=James L. Peters | year=1934 | title=Check-List of Birds of the World | volume=2 | publisher=Harvard University Press | location=Cambridge, Massachusetts  | page=24 | url=https://www.biodiversitylibrary.org/page/14482837 }}</ref> The genus name is a [[Latin]] word that was used for both the [[black grouse]] and the western capercaillie.<ref>{{ cite web | last=Jobling | first=James A. | title=Tetrao | work=The Key to Scientific Names | url=https://birdsoftheworld.org/bow/key-to-scientific-names/search?q=Tetrao | publisher=Cornell Lab of Ornithology | access-date=17 February 2025 }}</ref> The specific epithet ''urogallus'' is a [[Neo-Latin]] partial [[homophone]] of German ''Auerhuhn'', a western capercaillie.<ref>{{ cite web | last=Jobling | first=James A. | title=urogallus | work=The Key to Scientific Names | url=https://birdsoftheworld.org/bow/key-to-scientific-names/search?q=urogallus | publisher=Cornell Lab of Ornithology | access-date=17 February 2025 }}</ref> The word had been used in 1555 by the Swiss naturalist [[Conrad Gessner]] in his ''[[Historia animalium (Gessner book)|Historiae animalium]]''.<ref>{{cite book| last=Gesner | first=Conrad | author-link=Conrad Gessner | title=Historiae animalium liber III qui est de auium natura. Adiecti sunt ab initio indices alphabetici decem super nominibus auium in totidem linguis diuersis: & ante illos enumeratio auium eo ordiné quo in hoc volumine continentur | year=1555 | publisher= Froschauer | location=Zurich | language=Latin | page=472 | url=https://www.biodiversitylibrary.org/page/52661354 }}<!--Linnaeus cited a different edition.--></ref>

The common name ''capercaillie'' is a corruption of the [[Scottish Gaelic language|Scottish Gaelic]] ''capall coille'' ({{IPA|gd|kʰaʰpəɫ̪ˈkʰɤʎə}}) "Horse of the woodland". The [[Scots language|Scots]] borrowing is spelled ''capercailzie'' (the Scots use of z represents an archaic spelling with [[yogh]] and is silent;{{NoteTag|There exists a spelling pronunciation {{IPAc-en|-|l|z|i}}.<ref name="CEPD" />}} see [[Mackenzie (surname)]]). The current spelling was standardised by [[William Yarrell]] in 1843.<ref name=ODBBN/>

Its closest relative is the [[black-billed capercaillie]] (''Tetrao urogalloides''), which breeds in the larch [[taiga]] forests of eastern [[Russia]] and parts of northern [[Mongolia]] and [[China]].

===Subspecies===
The western capercaillie has 8 recognized [[subspecies]]:<ref name=ioc>{{cite web| editor1-last=Gill | editor1-first=Frank | editor1-link=Frank Gill (ornithologist) | editor2-last=Donsker | editor2-first=David | editor3-last=Rasmussen | editor3-first=Pamela | editor3-link=Pamela C. Rasmussen | date=August 2024 | title=Pheasants, partridges, francolins | work=IOC World Bird List Version 14.2 | url=https://www.worldbirdnames.org/new/bow/pheasants/ | publisher=International Ornithologists' Union | access-date=18 February 2025}}</ref>

*''[[Cantabrian capercaillie|T. u. cantabricus]]'' <small>(Castroviejo, 1967) -</small> northwestern [[Spain]]
*''T. u. aquitanicus'' (<small>Ingram, 1915) -</small> [[Pyrenees]] of [[Spain]] and [[France]]
*''T. u. crassirostris''  <small>(C.L. Brehm, 1831) -</small> [[Alps]] to [[Estonia]] 
*''T. u. rudolfi'' <small>(Dombrowski, 1912) -</small> [[Bulgaria]] to southwestern [[Ukraine]] 
*''T. u. urogallus'' <small>([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758)]] -</small> [[Scandinavia]] and [[Scotland]]
*''T. u. karelicus'' <small>(Lönnberg, 1924) -</small> [[Finland]] and [[Karelia]]
*''T. u. lonnbergi'' <small>([[Sergey Snigirewski|Snigirevski]], 1957) -</small> [[Kola Peninsula]]
*''T. u. pleskei'' <small>(Stegmann, 1926) -</small>  [[Belarus]] ([[Russia]])
*''T. u. obsoletus'' <small>([[Sergey Snigirewski|Snigerewski]], 1937) -</small> northern European [[Russia]]
*''T. u. volgensis'' <small>([[Sergei Buturlin|Buturlin]], 1907) -</small> found in southeastern European [[Russia]]
*''T. u. uralensis'' <small>(Nazarov, 1886) -</small> found in the [[Urals]] and [[western Siberia]]
*''T. u. taczanowskii'' <small>(Stejneger, 1885) -</small>  central [[Siberia]] to [[Altai Mountains]] (northwest [[Mongolia]] and eastern [[Kazakhstan]])

Subspecies of the western capercaillie show increasing amounts of white on the underparts of males distributed west to east, almost wholly black with only a few white spots underneath in western and central Europe to nearly pure white in Siberia, where the [[black-billed capercaillie]] is located. There is less variation in the females of this species. 

A native Scottish population of western capercaillie which became extinct between 1770 and 1785 was probably a distinct subspecies, although it was never formally described as such. The western capercaillie found in [[Scotland]] is an introduced population of the [[nominate subspecies]] ''urogallus''.<ref>{{Cite taxon|BOW |last1=de Juana |first1=Eduardo |last2=Kirwan |first2=Guy M. |date=2020 |title=Western Capercaillie (''Tetrao urogallus'')|version=1.0 |url=https://birdsoftheworld.org/bow/species/wescap1/cur/introduction |language=en |doi=10.2173/bow.wescap1.01|url-access=subscription }}</ref>

===Hybrids===
Western capercaillies are known to hybridise occasionally with [[black grouse]] (these hybrids being known by the German name ''[[Rackelhahn]]'') and the closely related black-billed capercaillie.

==Description==
[[File:Western Capercaillie Spain.jpg|thumb|left|Cock singing during courting season in the Spanish Pyrenees]]
[[File:Tjädertupp och tjäderhöna, Iduns kokbok.jpg|thumb|right|Male and female]]
[[File:Grand Tétra MHNT.jpg|thumb|Skeleton of ''Tetrao urogallus'']]
Male and female western capercaillie can easily be differentiated by their size and colouration. The cock is much bigger than the hen. It is one of the most [[Sexual dimorphism|sexually dimorphic]] in size of living bird species, only exceeded by the larger types of [[bustard]]s and a select few members of the [[Phasianidae|pheasant]] family.

Cocks (males) typically range from {{convert|74|to|85|cm|in}} in length with wingspan of {{cvt|90|to|125|cm|in}} and an average weight of {{cvt|4.1|kg|lboz}}.<ref name=ARKive/><ref name=WAZA/><ref name=CRC/> The largest wild cocks can attain a length of {{cvt|100|cm|in|-1}} and weight of {{cvt|6.7|kg|lboz}}.<ref name=BBCNature/> The largest specimen recorded in captivity had a weight of {{cvt|7.2|kg|lboz}}. The weight of 75 wild cocks was found to range from {{cvt|3.6|to|5.05|kg|lboz}}.<ref name=CRC/> The body [[feather]]s are dark grey to dark brown, while the breast feathers are dark metallic green. The belly and undertail [[Wikt:covert#Noun|coverts]] vary from black to white depending on race (see below).

The hen (female) is much smaller, weighing about half as much as the cock. The capercaillie hen's body from beak to tail is approximately {{cvt|54|–|64|cm|in}} long, the wingspan is {{cvt|70|cm|in}} and weighs {{cvt|1.5|–|2.5|kg|lboz}}, with an average of {{cvt|1.8|kg|lboz}}.<ref name=CRC/> Feathers on the upper parts are brown with black and silver barring; on the underside they are more light and buffish yellow.

Both sexes have a white spot on the wing bow. They have feathered legs, especially in the cold season, for protection against cold. Their toe rows of small, elongated horn tacks provide a [[snowshoe]] effect that led to the German family name "Rauhfußhühner", literally translated as "rough-footed hens".

These so-called "courting tracks" make a clear track in the snow. The sexes can be distinguished very easily by the size of their footprints.

There is a bright red spot of naked skin above each eye. In German hunters' language, these are the so-called "roses"{{Failed verification|date=October 2025}}.

The small chicks resemble the hen in their cryptic colouration, which is a passive protection against predators. Additionally, they wear black crown feathers. At an age of about three months, in late summer, they moult gradually towards the adult plumage of cocks and hens. The [[Egg (biology)|egg]]s are about the same size and form as chicken eggs, but are more speckled with brown spots.

==Distribution and habitat==
[[File:Il gallo gedroni nel Parco Nazionale dello Stelvio.jpg|thumb|left|Male capercaillie the [[Stelvio National Park]], Italy.]]

The capercaillie is a non-migratory [[Wikt:sedentary|sedentary]] species, breeding across northern parts of Europe and the [[Palearctic]] in mature [[conifer]] [[forest]]s with diverse [[species composition]] and a relatively open canopy structure.

[[File:Keski-Suomi Coat of Arms.svg|thumb|upright|A capercaillie in the coat of arms of the [[Central Finland|Central Finland region]]. It is also the official regional bird.<ref name="keskisuomi">[https://keskisuomi.fi/ennakointi-ja-tietopalvelut/maakuntatunnukset/ Maakuntatunnukset] – Keski-Suomen Liitto (in Finnish)</ref>]]

At one time it was present in all the [[taiga]] forests of the [[Palearctic]] in the cold temperate [[latitude]]s and the coniferous forest belt in the mountain ranges of warm temperate Europe. The [[Scotland|Scottish]] population became [[Extinction|extinct]], but has been reintroduced from the [[Sweden|Swedish]] population; in [[Germany]] it is on the "Red List" as a species threatened by extinction and is no longer found in the lower mountainous areas of [[Bavaria]]; in the [[Bavarian Forest]], the [[Black Forest]] and the [[Harz]] mountains numbers of surviving western capercaillie decline even under massive efforts to breed them in captivity and release them into the wild. In [[Switzerland]], they are found in the [[Swiss Alps]] and in the [[Jura Mountains|Jura]]; they are also present in the Austrian and Italian Alps. In [[Ireland]] it was common until the 17th century, but was extirpated in the 18th century. In [[Norway]], [[Sweden]], [[Finland]], [[Russia]] and [[Romania]] populations are large, and it is a common bird to see in forested regions; especially in [[Central Finland]], where it occurs in the coat of arms of the [[Regions of Finland|region]] and is also a regional bird.<ref name="keskisuomi"/><ref>Iltanen, Jussi: ''Suomen kuntavaakunat'' (2013), Karttakeskus, {{ISBN|951-593-915-1}}</ref>

The most serious threats to the species are [[habitat degradation]], particularly conversion of diverse native [[forest]] into often single-species timber [[plantation]]s, and to birds colliding with [[agricultural fencing|fences]] erected to keep [[deer]] out of young plantations. Increased numbers of small predators that prey on capercaillies (e.g., [[red fox]]) due to the loss of large predators who control smaller carnivores (e.g., [[gray wolf]], [[brown bear]]) cause problems in some areas.

===Status and conservation===
[[File:Foot print of Tetrao urogallus in Kladské rašeliny.jpg|thumb|Footprints of western capercaillie in the Czech national nature reserve [[Kladské rašeliny]]]]
This species has an estimated range of {{convert|1000000|–|10000000|km2|sqmi|abbr=on}} and a population of between 1.5 and 2 million individuals in Europe alone. There is some evidence of a population decline,<ref>{{cite journal |last1=Gil |first1=Juan Antonio |last2=Gómez-Serrano |first2=Miguel Ángel |last3=López-López |first3=Pascual |title=Population Decline of the Capercaillie Tetrao urogallus aquitanicus in the Central Pyrenees |journal=Ardeola |date=2020 |volume=67 |issue=2 |pages=285–306 |doi=10.13157/arla.67.2.2020.ra4 |s2cid=216382815 |url=https://bioone.org/journals/ardeola/volume-67/issue-2/arla.67.2.2020.ra4/Population-Decline-of-the-Capercaillie-Tetrao-urogallus-aquitanicus-in-the/10.13157/arla.67.2.2020.ra4.short |issn=0570-7358|url-access=subscription }}</ref> but the overall species is not believed to approach the IUCN Red List threshold of a population decline of more than 30% in ten years or three generations. It is therefore evaluated as [[least concern]].<ref name="iucn" />

As reported by the Spanish researcher [[Félix Rodríguez de la Fuente]] in his "Fauna" series, the northwestern Spanish subspecies ''[[Cantabrian capercaillie|T. u. cantabricus]]''—an Ice Age remnant—was threatened in the 1960s by commercial gathering of [[holly]] fruit-bearing branches for sale as Christmas ornaments—a practice imported from [[Anglo-Saxon]] or [[Germanic peoples|Germanic]] countries.

In [[Scotland]], the population has declined greatly since the 1960s because of deer fencing, predation and lack of suitable habitat ([[Caledonian Forest]]). The population plummeted from a high of 10,000 pairs in the 1960s to fewer than 1000 birds in 1999. It was even named as the bird most likely to become extinct in the [[United Kingdom|UK]] by 2015, a survey then identified 1114 birds, occupying a reduced range of terrain. In mountainous skiing areas, poorly marked cables for [[Platter lift|ski-lifts]] have contributed to mortality. Their effects can be mitigated by proper coloring, sighting and height alterations.

A study published in 2022 by [[NatureScot]] scientific advisory committee<ref>{{Cite web |title=Review of Capercaillie Conservation and Management - Report to the Scientific Advisory Committee |url=https://www.nature.scot/doc/review-capercaillie-conservation-and-management-report-scientific-advisory-committee |access-date=2022-02-26 |website=NatureScot |language=en}}</ref> recommended 'renewed intensive measures' to maintain the population, especially steps to assist in the survival of eggs and chicks. Predators like crows, foxes and [[European pine marten|pine martens]] are blamed for the decline, as well as the [[Agricultural fencing|deer fences]], and increased human recreation in the territory which can injure adult birds.It was declared as 'extremely vulnerable' and requiring urgent action. [[Biodiversity]] Minister for Scotland, [[Lorna Slater]], MSP described capercaillie as 'magnificent birds' and 'iconic' for Scotland and called for 'partnership working' to reverse the decline.<ref>{{Cite news |last=Young |first=Gregor |date=26 February 2022 |title=New extinction fears for the capercaillie |page=21 |work=The National}}</ref>

==Behaviour and ecology==
The western capercaillie is adapted to its original habitats—old coniferous forests with a rich interior structure and dense ground vegetation of ''[[Vaccinium]]'' species under a light canopy. They mainly feed on ''Vaccinium'' species, especially [[bilberry]], find cover in young tree growth, and use the open spaces when flying. As habitat specialists, they hardly use any other forest types.

Western capercaillies are not elegant fliers due to their body weight and short, rounded wings. While taking off they produce a sudden thundering noise that deters predators. Because of their body size and wingspan they avoid young and dense forests when flying. While flying they rest in short gliding phases. Their feathers produce a whistling sound.

[[File:Western Capercaillie (Tetrao urogallus) (W1CDR0001418 BD47).ogg|thumb|left|Capercaillie with her chicks, recorded in Scotland]]

Western capercaillie, especially the hens with young chicks, require resources that should occur as parts of a small-scaled patchy mosaic: These are food plants, small insects for the chicks, cover in dense young trees or high ground vegetation, old trees with horizontal branches for sleeping. These criteria are met best in old forest stands with spruce and pine, dense ground vegetation and local tree regrowth on dry slopes in southern to western expositions. These open stands allow flights downslope, and the tree regrowth offers cover.

In the lowlands such forest structures developed over centuries by heavy exploitation, especially by the use of litter and grazing [[livestock]]. In the highlands and along the ridges of mountain areas in temperate Europe as well as in the taiga region from [[Fennoscandia]] to Siberia, the [[boreal forest]]s show this open structure due to the harsh climate, offering optimal habitats for capercaillie without human influence. Dense and young forests are avoided as there is neither cover nor food, and flight of these large birds is greatly impaired.

The abundance of western capercaillie depends—as with most species—on habitat quality. It is highest in sun-flooded open, old mixed forests with spruce, pine, fir and some beech with a rich ground cover of ''Vaccinium'' species.

[[File:Ferdinand von Wright - Taistelevat metsot - 1886 - oljymaalaus - Ateneumin taidemuseo.png|thumb|[[Ferdinand von Wright]], ''The Fighting Capercaillies'' (''Taistelevat metsot''), 1886]]

Spring territories are about {{convert|25|ha|acre}} per bird. Comparable abundances are found in taiga forests. Thus, the western capercaillie never had particularly high densities, despite the legends that hunters may speculate about. Adult cocks are strongly territorial and occupy a range of {{convert|50|to|60|ha|acre}} optimal habitat. Hen territories are about {{convert|40|ha|acre|-1}}. The annual range can be several square kilometres (hundreds of hectares) when storms and heavy snowfall force the birds to winter at lower altitudes. Territories of cocks and hens may overlap.

Western capercaillie are diurnal game, i.e., their activity is limited to the daylight hours. They spend the night in old trees with horizontal branches. These sleeping trees are used for several nights; they can be mapped easily as the ground under them is covered by pellets.

The hens are ground breeders and spend the night on the nest. As long as the young chicks cannot fly, the hen spends the night with them in dense cover on the ground. During winter the hens rarely go down to the ground and most tracks in the snow are from cocks.

==Diet==
The western capercaillie lives on a variety of food types, including buds, leaves, [[Berry|berries]], [[insect]]s, grasses and in the winter mostly conifer needles. One can see the food remains in their droppings, which are about {{cvt|1|cm|in|frac=2}} in diameter and {{cvt|5|–|6|cm|in|frac=2}} in length. Most of the year the droppings are of solid consistency but, with the ripening of [[Blueberry|blueberries]], these dominate the diet and the [[faeces]] become formless and bluish black.

The western capercaillie is a highly specialized [[herbivore]], which feeds almost exclusively on blueberry leaves and berries with some grass seeds and fresh shoots of [[Cyperaceae|sedge]]s in summertime. The young chicks are dependent on [[protein]]-rich food in their first weeks and thus mainly prey on insects. Available insect supply is strongly influenced by weather—dry and warm conditions allow a fast growth of the chicks, cold and rainy weather leads to high mortality.

During winter, when a high snow cover prevents access to ground vegetation, the western capercaillie spends almost all day and night in trees, feeding on coniferous needles of [[spruce]], [[pine]] and [[fir]] as well as on buds from [[beech]] and [[rowan]].

To digest this coarse winter food, the birds need grit: small stones or [[gastrolith]]s which they actively search for and devour. With their very muscular [[stomach]]s, gizzard stones function like a mill and break needles and buds into small particles. Additionally, western capercaillie have two [[vermiform appendix|appendixes]] which grow very long in winter. With the aid of [[Symbiosis|symbiotic]] [[bacteria]], the plant material is [[Digestion|digested]] there. During the short winter days the western capercaillie feeds almost constantly and produces a [[Pellet (ornithology)|pellet]] nearly every 10 minutes.

A recent study using DNA from faeces in Norway and France found that their diet is much more varied than had been documented.<ref>{{cite journal |last1=Chua |first1=Physilia Ying Shi |last2=Lammers |first2=Youri |last3=Menoni |first3=Emmanuel |last4=Ekrem |first4=Torbjørn |last5=Bohmann |first5=Kristine |last6=Boessenkool |first6=Sanne |last7=Alsos |first7=Inger Greve |title=Molecular dietary analyses of western capercaillies (''Tetrao urogallus'') reveal a diverse diet |journal=Environmental DNA |date=13 July 2021 |volume=3 |issue=6 |pages=1156–1171 |doi=10.1002/edn3.237|hdl=10037/22006 |s2cid=238773874 |hdl-access=free }}</ref>

==Courting and reproduction==
[[File:Tetrao urogallus -Bayerischer Wald, Europe -female-8a (1).jpg|thumb|Female in [[Bavarian Forest]], Germany]]
[[File:Grand Tétras MHNT.jpg|thumb|''Tetrao urogallus urogallus''—eggs]]
[[File:Capercaillie(2).JPG|thumb|left|Male capercaillie marking his territory to a hiker in a Finnish taiga forest]]

The [[seasonal breeder#breeding season|breeding season]] of the western capercaillie starts according to spring weather progress, vegetation development and altitude between March and April and lasts until May or June. Three-quarters of this long courting season is mere territorial competition between neighbouring cocks or cocks on the same courting ground.

At the very beginning of dawn, the tree courting begins on a thick branch of a lookout tree. The cock postures himself with raised and fanned tail feathers, erect neck, beak pointed skywards, wings held out and drooped and starts his typical aria to impress the females. The typical song in this display is a series of double-clicks like a dropping ping-pong ball, which gradually accelerate into a popping sound like a cork coming off a champagne bottle, which is followed by scraping sounds.

Towards the end of the courting season the hens arrive on the courting grounds, also called [[Lek mating|"lek"]], [[Swedish language|Swedish]] for "play". The cocks continue courting on the ground: This is the main courting season. The cock flies from his courting tree to an open space nearby and continues his display. The hens, ready to get mounted, crouch and utter a begging sound. If there is more than one cock on the lek, it is mainly the alpha-cock who engages in [[Copulation (zoology)|copulation]] with the hens. In this phase western capercaillies are most sensitive to disturbances. Even single human observers may cause the hens to fly off and prevent copulation in this very short time span where they are ready for conception.

In [[Scandinavia]] and in Scotland, male western capercaillies are well-known for their combative behavior during mating season, sometimes even challenging and chasing off people who enter their territory.<ref>{{cite news |title=Sex-crazed grouse terrorizes Swedish family |url=https://www.thelocal.se/20150503/sex-crazed-grouse-terrorises-family |access-date=8 May 2020 |work=The Local |date=3 May 2015}}</ref><ref>{{cite web |last1=Suter |first1=Paul |title=Capercaillie in Finland |url=https://toomuchtosee.com/capercaillie-in-finland/ |website=Too Much To See |date=12 November 2019 |access-date=8 May 2020}}</ref><ref>{{cite web |title=Capercaillie |url=https://harjureitti.fi/en/nature/other-trails/capercaillie/ |website=Harjureitti |access-date=8 May 2020}}</ref> In a study it was found that the testosterone level in such "deviant" males was about five times higher than that of normal displaying males.<ref>{{cite journal |last1=MILONOFF |first1=M |title=The abnormal conduct of capercaillies ''Tetrao urogallus'' |journal=Hormones and Behavior |date=December 1992 |volume=26 |issue=4 |pages=556–567 |doi=10.1016/0018-506X(92)90022-N|pmid=1478639 |s2cid=22285083 }}</ref>

There is a smaller courting peak in autumn, which serves to delineate the territories for the winter months and the next season.

===Egg-laying===
About three days after copulation the hen starts laying eggs. In 10 days the clutch is full. The average clutch size is eight eggs but may amount up to 12, rarely only four or five eggs. Brooding lasts about 26–28 days according to weather and altitude.

At the beginning of the brooding season, the hens are very sensitive to disturbances and leave the nest quickly. Towards the end they tolerate disturbances to a certain degree, crouching on their nest which is usually hidden under low branches of a young tree or a broken [[crown (botany)|tree crown]]. As hatching nears, hens sit tighter on the nest and will only flush from the nest if disturbed in very close proximity. Nesting hens rarely spend more than an hour a day off of the nest feeding and as such become somewhat constipated. The presence of a nest nearby is often indicated by distinctively enlarged and malformed droppings known as "clocker droppings". All eggs hatch in close proximity after which the hen and clutch abandon the nest where they are at their most vulnerable. Abandoned nests often contain "caeacal" droppings; the discharge from the hens' appendixes built up over the incubation period.

===Hatching and growth===
After hatching the chicks are dependent on getting warmed by the hen. Like all [[precocial]] birds, the young are fully covered by down feathers at hatching but are not able to maintain their body temperature which is {{cvt|41|C|F}} in birds. In cold and rainy weather the chicks need to get warmed by the hen every few minutes and all night.

They seek food independently and prey mainly on insects, like [[butterfly]] [[caterpillar]]s and [[pupa]]e, [[ant]]s, [[myriapoda]]e, ground [[beetle]]s.

They grow rapidly and most of the energy intake is transformed into the protein of the flight musculature (the white flesh around the breast in chickens). At an age of 3–4 weeks they are able to perform their first short flights. From this time on they start to sleep in trees on warm nights. At an age of about 6 weeks they are fully able to maintain their body temperature. The down feathers have been moulted into the immature plumage and at an age of 3 months another moult brings in their subadult plumage; now the two sexes can be easily distinguished.

From the beginning of September the families start to dissolve. First the young cocks disperse, then the young hens. Both sexes may form loose foraging groups over the winter.

==Predation and hunting==
Mammalian predators known to take capercaillie include [[Eurasian lynx]] (''Lynx lynx'') and [[gray wolf]] (''Canis lupus''), although they prefer slightly larger prey. Meanwhile, [[European pine marten]]s (''Martes martes''), [[beech marten]]s (''Martes foina''), [[brown bear]]s (''Ursus arctos''), [[wild boar]]s (''Sus scrofa'') and [[red fox]]es (''Vulpes vulpes'') take mostly eggs and chicks but can attack adults if they manage to ambush the often wary birds.<ref name=Odden2006/><ref name=Muller2006/><ref name=Saniga2002/><ref name=Wegge2007/><ref name=Smedshaug1999/> In [[Sweden]], western capercaillies are the primary prey of the [[golden eagle]] (''Aquila chrysaetos'').<ref name=Tjernberg1981/> Large numbers are taken by [[Eurasian goshawk]]s (''Astur gentilis''), including adults but usually young ones, and [[Eurasian eagle-owl]]s (''Bubo bubo'') will occasionally pick off a capercaillie of any age or size; they normally prefer mammalian foods.<ref name=Kenward2006/><ref name=Voous/> [[White-tailed eagle]]s (''Haliaeetus albicilla'') are more likely to take [[water bird]]s than upland-type birds but have been recorded preying on capercaillie around the [[White Sea]].<ref name=Koryakin2005/>

A traditional [[Game (hunting)|gamebird]], the capercaillie has been widely hunted with guns and dogs throughout its territory in central and northern Europe. This includes [[trophy hunting]] and hunting for food. Since hunting has been restricted in many countries, trophy-hunting has become a tourist resource, particularly in central European countries. In some areas, declines are due to excessive hunting, though this has not generally been a global problem. The bird has not been hunted in [[Scotland]] or Germany for over 30 years.<ref name="CLP">{{cite web|url=http://www.capercaillie-life.info/htm/bird_world_europe.php|archive-url=https://web.archive.org/web/20070818174603/http://www.capercaillie-life.info/htm/bird_world_europe.php|url-status=usurped|archive-date=August 18, 2007|title=Capercaillie Life Project|access-date=2015-12-25}}</ref>

===Notes===
{{NoteFoot}}

==References==
{{Reflist|refs=
<ref name=ARKive>{{cite web |url=http://www.arkive.org/capercaillie/tetrao-urogallus/ |title=Capercaillie (''Tetrao urogallus'') |website=[[ARKive]] |access-date=2012-12-26 |archive-url=https://web.archive.org/web/20120823055948/http://www.arkive.org/capercaillie/tetrao-urogallus/ |archive-date=2012-08-23 }}</ref>

<ref name=BBCNature>{{cite web |url=https://www.bbc.co.uk/nature/life/Western_Capercaillie |publisher=BBC Nature – Wildlife |title=Capercaillie |access-date=2012-06-21 |archive-url=https://web.archive.org/web/20171021234421/http://www.bbc.co.uk/nature/life/Western_Capercaillie |archive-date=2017-10-21 }}</ref>

<ref name=CRC>{{cite book |title=CRC Handbook of Avian Body Masses |editor-first=John B. Jr. |editor-last=Dunning |publisher=CRC Press |year=1992 |isbn=978-0-8493-4258-5}}</ref>

<ref name=Kenward2006>{{cite book |last=Kenward |first=R. |year=2006 |title=The Goshawk |publisher=Poyser Monographs, T. & A.D. Poyser / A. & C. Black |location=London |isbn=978-0-7136-6565-9}}</ref>

<ref name=Koryakin2005>{{cite conference |last1=Koryakin |first1=A.S. |last2=Boyko |first2=N.S. |date=November 2005 |title=The White tailed Sea Eagle ''Haliaeetus albicilla'' and the Common Eider ''Somate ria mollissima'' in the Gulf of Kandalaksha, White Sea |work=Status of Raptor Populations in Eastern Fennoskandia |conference=Proceedings of the Workshop, Kostomuksha |location=Karelia, Russia |pages=49–55 |url=http://www.krc.karelia.ru/doc_download.php?id=740&table_name=publ&table_ident=2403}}</ref>

<ref name=Muller2006>{{cite thesis |last=Müller |first=S. |year=2006 |title=Diet composition of wolves (Canis lupus) on the Scandinavian peninsula determined by scat analysis |publisher=School of Forest Science and Resource Management, Technical University of München, Germany |url=http://www.slu.se/Documents/externwebben/nj-fak/ekologi/forskning/skandulv%20dokument/M%C3%BCller%202006%20Diet%20composition%20of%20wolves%20on%20the%20Scandinavian%20peninsula%20determined%20by%20scat%20analysis.pdf |access-date=2015-05-01 |archive-url=https://web.archive.org/web/20160304204645/http://www.slu.se/Documents/externwebben/nj-fak/ekologi/forskning/skandulv%20dokument/M%C3%BCller%202006%20Diet%20composition%20of%20wolves%20on%20the%20Scandinavian%20peninsula%20determined%20by%20scat%20analysis.pdf |archive-date=2016-03-04 }}</ref>

<ref name=ODBBN>{{cite book |title=The Oxford Dictionary of British Bird Names |last=Lockwood |first=W.B. |year=1993 |publisher=[[OUP]] |isbn=978-0-19-866196-2}}</ref>

<ref name=Odden2006>{{cite journal |last1=Odden |first1=J. |last2=Linnell |first2=J.D. |last3=Andersen |first3=R. |year=2006 |title=Diet of Eurasian lynx, Lynx lynx, in the boreal forest of southeastern Norway: the relative importance of livestock and hares at low roe deer density |journal=European Journal of Wildlife Research |volume=52 |issue=4 |pages=237–244 |doi=10.1007/s10344-006-0052-4|bibcode=2006EJWR...52..237O |s2cid=23472006 }}</ref>

<ref name=Saniga2002>{{cite journal |last=Saniga |first=M. |year=2002 |title=Nest loss and chick mortality in capercaillie (''Tetrao urogallus'') and hazel grouse (''Bonasa bonasia'') in West Carpathians |journal=Folia Zoologica-Praha |volume=51 |issue=3 |pages=205–214}}</ref>

<ref name=Smedshaug1999>{{cite journal |last1=Smedshaug |first1=C.A. |last2=Selås |first2=V. |last3=Lund |first3=S.E. |last4=Sonerud |first4=G.A. |year=1999 |title=The effect of a natural reduction of red fox Vulpes vulpes on small game hunting bags in Norway |journal=Wildlife Biology |volume=5 |issue=3 |pages=157–166|doi=10.2981/wlb.1999.020 |bibcode=1999WildB...5..157S |s2cid=90693193 }}</ref>

<ref name=Tjernberg1981>{{cite journal |last1=Tjernberg |first1=Martin |year=1981 |title=Diet of the Golden Eagle ''Aquila chrysaetos'' during the Breeding Season in Sweden |journal=Holarctic Ecology |volume=4 |issue=1 |pages=12–19 |doi=10.1111/j.1600-0587.1981.tb00975.x|bibcode=1981Ecogr...4...12T }}</ref>

<ref name=Voous>{{cite book |last=Voous |first=K.H. |year=1988 |title=Owls of the Northern Hemisphere |publisher=MIT Press |isbn=978-0-262-22035-4}}</ref>

<ref name=WAZA>{{cite web |url=http://www.waza.org/en/zoo/choose-a-species/birds/pheasants-grouse-chickens-quails-and-relatives-galliformes/tetrao-urogallus |title=Western capercaillie |publisher=[[World Association of Zoos and Aquariums]] (WAZA) |access-date=2012-06-21 |archive-url=https://web.archive.org/web/20110107034240/http://www.waza.org/en/zoo/choose-a-species/birds/pheasants-grouse-chickens-quails-and-relatives-galliformes/tetrao-urogallus |archive-date=2011-01-07 }}</ref>

<ref name=Wegge2007>{{cite journal |last1=Wegge |first1=P. |last2=Kastdalen |first2=L. |date=January 2007 |title=Pattern and causes of natural mortality of capercaille, ''Tetrao urogallus'', chicks in a fragmented boreal forest |journal=Annales Zoologici Fennici |pages=141–151 |url=http://www.sekj.org/PDF/anzf44/anzf44-141.pdf |issn=0003-455X}}</ref>
}}

==External links==
{{Commons category|Tetrao urogallus}}
{{Wikispecies|Tetrao urogallus}}
{{EB1911 poster|Capercally}}
* [http://ibc.lynxeds.com/video/western-capercaillie-tetrao-urogallus/video-shows-spectacular-capercaillie-mating-game Capercaillie mating game] on the Internet Bird Collection
* [https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/capercaillie/ Capercaillie at RSPB Birds by Name]
* {{usurped|1=[https://web.archive.org/web/20070224172229/http://www.aigas.co.uk/Capercaillie-ecology-g.asp Aigas Field Centre Capercaillie Ecology and breeding programme pages]}}
* {{usurped|1=[https://web.archive.org/web/20120603060232/http://www.janneheimonen.net/Gallery/Birds/Western-Capercaillie-Tetrao-urogallus/1/ Western Capercaillie]}}—pictures in nature photographer Janne Heimonen's photo gallery
* {{BirdLife|22679487|Tetrao urogallus}}
* {{Avibase|name=Tetrao urogallus}}
* {{InternetBirdCollection|western-capercaillie-tetrao-urogallus}}
* {{VIREO|Capercaillie}}
* {{IUCN_Map|22679487/166188330|Tetrao urogallus}}
* {{Xeno-canto species|Tetrao|urogallus|Western capercaillie}}

{{Birds|state=collapsed}}
{{Phasianidae|state=collapsed}}
{{Portal bar|Birds|Animals|Biology|Scotland}}
{{Taxonbar |from=Q129059}}
{{Authority control}}

[[Category:Birds described in 1758]]
[[Category:Birds of Europe]]
[[Category:Birds of Russia]]
[[Category:Grouse]]
[[Category:Animal taxa named by Carl Linnaeus]]
[[Category:Tetrao]]