{{Short description|Species of bird}} {{Speciesbox | image = Perisoreus infaustus Kittilä 20180418 01.jpg | image_caption = Near Kittilä, Finland | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=BirdLife International |date=2016 |title=''Perisoreus infaustus'' |volume=2016 |article-number=e.T22705775A87356809 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22705775A87356809.en |access-date=12 November 2021}}</ref> | taxon = Perisoreus infaustus | authority = (Linnaeus, 1758) | synonyms = *''Corvus infaustus'' {{small|Linnaeus, 1758}} *''Lanius infaustus'' {{small|Linnaeus, 1766}} |synonyms_ref = <ref name = Avibase>{{cite web |url=https://avibase.bsc-eoc.org/species.jsp?avibaseid=43E6246776E789EC | title = Siberian Jay ''Perisoreus infaustus'' (Linnaeus, 1758) | access-date = 2 July 2017 | publisher = Denis Lepage | work = Avibase}}</ref> |range_map = PerisoreusInfaustusIUCNver2020-1.png |range_map_caption= Current approximate range according to the IUCN }}
The '''Siberian jay''' ('''''Perisoreus infaustus''''') is a small jay with a widespread distribution within the coniferous forests in North Eurasia. It has grey-brown plumage with a darker brown crown and a paler throat. It is rusty-red in a panel near the wing-bend, on the undertail coverts and on the sides of the tail. The sexes are similar. Although its habitat is being fragmented, it is a common bird with a very wide range so the International Union for Conservation of Nature has assessed its conservation status as being of "least concern".
==Taxonomy and systematics== The Siberian jay was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his ''Systema Naturae'' under the binomial name ''Corvus infaustus''.<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=107 | publisher=Laurentii Salvii | place=Holmiae (Stockholm) | language=Latin |url=https://www.biodiversitylibrary.org/page/727012 }}</ref> Linnaeus specified the location as "Europae alpinis sylvis" but the type location was restricted to Sweden by Ernst Hartert in 1903.<ref>{{ cite book | editor1-last=Mayr | editor1-first=Ernst | editor1-link=Ernst Mayr | editor2-last=Greenway | editor2-first=James C. Jr | year=1962 | title=Check-List of Birds of the World | volume=15 | publisher=Museum of Comparative Zoology | place=Cambridge, Massachusetts | page=238 |url=https://www.biodiversitylibrary.org/page/14485611 }}</ref><ref>{{ cite book | last=Hartert | first=Ernst | author-link=Ernst Hartert | year=1903 | title=Die Vögel der paläarktischen Fauna | volume=1 | language=German | location=Berlin | publisher=R. Friedländer und Sohn | page=34 |url=https://www.biodiversitylibrary.org/page/14029823 }}</ref> The specific epithet ''infaustus'' is Latin meaning "unlucky" or "unfortunate" as Siberian jays were formerly considered a bad omen.<ref>{{cite book | last=Jobling | first=James A. | year=2010| title=The Helm Dictionary of Scientific Bird Names | publisher=Christopher Helm | location=London | isbn=978-1-4081-2501-4 | page=205 }}</ref> The Siberian jay is now placed together with the Canada jay and the Sichuan jay in the genus ''Perisoreus'' that was introduced in 1831 by Charles Lucien Bonaparte.<ref>{{ cite journal | last=Bonaparte | first=Charles Lucien | author-link=Charles Lucien Bonaparte | year=1831 | title=Saggio di una distribuzione metodica degli Animali Vertebrati di Carlo Luciano Bonaparte principe di Musignano | journal=Giornale Arcadico di Scienze, Lettre ed Arti | volume=49 | pages=3–77 [42] |url=https://biodiversitylibrary.org/page/10034645 }}</ref><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 Rasmussen | date=January 2021 | title=Crows, mudnesters, birds-of-paradise | work=IOC World Bird List Version 11.1 |url=https://www.worldbirdnames.org/bow/crows/ | publisher=International Ornithologists' Union | access-date=16 May 2021 }}</ref>
Five subspecies are recognised:<ref name=ioc/> * ''P. i. infaustus'' (Linnaeus, 1758) – Scandinavia to west Siberia (includes ''ruthenus'') * ''P. i. rogosowi'' Sushkin & Stegmann, 1929 – northeast European Russia to northcentral Siberia (includes ''ostjakorum'') * ''P. i. opicus'' Bangs, 1913 – east Kazakhstan, northwest China and south central Siberia * ''P. i. sibericus'' (Boddaert, 1783) – central Siberia and north Mongolia (includes ''yakutensis'' and ''tkachenkoi'') * ''P. i. maritimus'' Buturlin, 1915 – southeast Siberia and northeast China
The Siberian jay differs from the other two species in its group-living behaviours. Unlike the other two species, where group individuals unrelated to breeding parents may help provision the young,<ref name=Jing>{{Cite journal | last1=Jing | first1=Y. | last2=Fang | first2=Y. | last3=Strickland | first3=D. | last4=Lu | first4=N. | last5=Sun | first5=Y.-H. | date=2009 | title=Alloparenting in the rare Sichuan Jay (''Perisoreus internigrans'') | journal=The Condor | volume=111 | issue=4 | pages=662–667 | doi=10.1525/cond.2009.080114 | doi-access=}}</ref> the group individuals accompanying a breeding pair of Siberian jays do not help raise the offspring.<ref name="Ekman and Sklepkovych">{{Cite journal | last1=Ekman | first1=Jan | last2=Sklepkovych | first2=Bohdan | date=1994 | title=Conflict of interest between the sexes in Siberian jay winter flocks | journal=Animal Behaviour | volume=48 | issue=2 | pages=485–487 | doi=10.1006/anbe.1994.1266}}</ref> The lack of extra-parental care within the groups may be due to historic selection against cooperative breeding in the Siberian jay;<ref>{{Cite journal | last1=Ekman | first1=Jan | last2=Ericson | first2=Per G.P | date=2006 | title=Out of Gondwanaland; the evolutionary history of cooperative breeding and social behaviour among crows, magpies, jays and allies | journal=Proceedings of the Royal Society B: Biological Sciences | volume=273 | issue=1590 | pages=1117–1125 | doi=10.1098/rspb.2005.3431| pmid=16600890 | pmc=1560265 }}</ref> probably as an anti-predator strategy to avoid predator attention.<ref name=Jing/>
With the colonisation of coniferous forests in Scandinavia just after the last ice age, the Siberian jay probably expanded its range from east to west in response to the newly formed suitable habitat resulting from climatic warming.<ref name=Uimaniemi>{{Cite journal | last1=Uimaniemi | first1=L. | last2=Orell | first2=M. | last3=Mönkkönen | first3=M. | last4=Huhta | first4=E. | last5=Jokimäki | first5=J. | last6=Lumme | first6=J. | date=2000 | title=Genetic diversity in the Siberian jay ''Perisoreus infaustus'' in fragmented old-growth forests of Fennoscandia | journal=Ecography | volume=23 | issue=6 | pages=669–677 | doi=10.1111/j.1600-0587.2000.tb00310.x | doi-access=free | bibcode=2000Ecogr..23..669U }}</ref>
==Description== [[File:Siberian Jay (Perisoreus infaustus) 02.jpg|thumb|In a spruce forest near Evenstad, Norway]] The Siberian jay is the smallest of the western Palearctic corvids, weighing {{cvt|75|to|90|g}}<ref name = "Ekman and Griesser 2016"/> and measuring about {{convert|30|cm|in|0|abbr=off}} in length.<ref name = "Hogstad">{{ cite journal | last=Hogstad | first=Olaf | date=2016 | title=Hunting strategies by Siberian jays ''Perisoreus infaustus'' on wintering small rodents | journal=Ornis Norvegica | volume=39 | pages=25–28 | doi=10.15845/on.v39i0.1031 | doi-access=free }}</ref> The adult plumage is greyish brown, with a dark brown head, paler forehead and buff breast. The rump is yellowish and the chin and throat are grey. There is also rufous streaking on the outer feathers, and the bill and legs are black.<ref name = "Coombs">{{ cite book | last=Coombs | first=Franklin | date=1978 | title=The Crows: a Study of the Corvids of Europe | location=London | publisher=B.T. Batsford | oclc=610890402}}</ref> Their overall colouration is fairly inconspicuous to visually conceal them from predators within their forest habitat.<ref name=Blomgren>{{Cite journal | last=Blomgren | first=Arne | date=1971 | title=Studies of less familiar birds: 162 Siberian Jay | journal=British Birds | volume=64 | pages=25–28 |url=https://britishbirds.co.uk/wp-content/uploads/article_files/V64/V64_N01/V64_N01_P025_028_A005.pdf }}</ref> The plumage is also very soft and downy for insulation against extreme cold in winter.<ref name = "Coombs"/> There is one moult per year, which lasts from mid-June to mid-September.<ref name = "Coombs"/> The longest recorded lifetime is 13 years 4 months for a bird ringed in Finland,<ref>{{cite web |title=European Longevity Records |url=https://euring.org/data-and-codes/longevity-list?page=5 | publisher=Euring |access-date=17 May 2021 }}</ref> although the average lifespan has been reported as 7.1 years.<ref name="iucn status 12 November 2021" />
Siberian jays appear to be specially adapted to navigate in flight through dense forest despite being rather cumbersome flyers across open terrain. This may explain their vulnerability to predation by raptors outside forests.<ref name = "Fabricius">Fabritius H. 2010. Effective population size and the viability of the Siberian jay population of Suupohja, Finland. Master's thesis, University of Helsinki.</ref>
===Voice=== The Siberian jay is mostly silent, but it can emit a loud screech similar to that of a buzzard (Buteo spp.). Both sexes perform the song, which is mainly heard during the breeding season from a short distance away, and it comprises a wide repertoire of sounds. These range from sequences of separate soft and harsh notes to bouts of whistling, creaking and trilling.<ref name=Blomgren/><ref name = "Coombs"/> They are also adept vocal mimics, and have been recorded mimicking the vocalizations of 20 bird species as well as Eurasian red squirrels<ref>{{Cite journal |last=Littauer |first=Richard |last2=Darmstadt |first2=Sam |last3=Kirsch |first3=William M. |last4=Betchkal |first4=Davyd H. |date=2026-02-12 |title=Community-science sourced evidence of vocal mimicry in Perisoreus jays |url=https://www.tandfonline.com/doi/full/10.1080/15594491.2026.2616578 |journal=The Wilson Journal of Ornithology |language=en |pages=1–11 |doi=10.1080/15594491.2026.2616578 |issn=1559-4491|url-access=subscription }}</ref>. Siberian jays also engage in nepotistic alarming calls, which may serve to warn conspecifics of an approaching predator.<ref name = "Griesser 2013">{{Cite journal | last=Griesser | first=Michael | date=2013 | title=Do warning calls boost survival of signal recipients? Evidence from a field experiment in a group-living bird species | journal=Frontiers in Zoology | volume=10 | issue=1 | page=49 | doi=10.1186/1742-9994-10-49 | pmid=23941356 | pmc=3751016 | doi-access=free}}</ref> Experimental studies have shown that warning calls decrease the reaction time of non-breeding individuals in response to an approaching predator and improve their survival rate.<ref name = "Griesser 2013"/> However, females seem more able than males to differentiate between kin and non-kin.<ref name=Griesser2004>{{Cite journal | last1=Griesser | first1=Michael | last2=Ekman | first2=Jan | date=2004 | title=Nepotistic alarm calling in the Siberian jay, ''Perisoreus infaustus'' | journal=Animal Behaviour | volume=67 | issue=5 | pages=933–939 | doi=10.1016/j.anbehav.2003.09.005 }}</ref> Alongside directly warning to family group members, a breeding female's nepotistic alarm calls may also divert a predator's attention away from her offspring.<ref name =Griesser2004/>
==Distribution and habitat== The Siberian jay is resident in the northern boreal spruce, pine, cedar and larch forests stretching from Scandinavia to northern Russia and Siberia.<ref name=Blomgren/> The species has an extensive range, estimated at {{convert|19300000|km2|sqmi|abbr=off}}<ref name="iucn status 12 November 2021" /> and is native to Norway, Sweden, Finland, Russia, Mongolia, Kazakhstan and China.<ref name="iucn status 12 November 2021" /> It is vagrant in Belarus, Estonia, Latvia, Poland, Slovakia and Ukraine.<ref name="iucn status 12 November 2021" /> Despite being largely sedentary, some southward movement may occur in winter among individuals in the eastern part of the range.<ref name = "Madge">Madge S. 2009. Siberian Jay (''Perisoreus infaustus''). In: del Hoyo J, Elliot A, Sargatal J. Christie DA, de Jauna E.(eds). ''Handbook of the Birds of the World Alive''. Lynx Edicions, Barcelona.</ref>
This species prefers dense, mature forest habitat with a closed canopy in lowland and foothill areas.<ref name="Madge"/> Spruce forests are preferred for foraging and nesting habitat because spruce's denser foliage provides better concealment from predators than that of other local conifers.<ref name="Edenius and Meyer 2002">{{ cite journal | last1=Edenius | first1=Lars | last2=Meyer | first2=Carsten | date=2002 | title=Activity budgets and microhabitat use in the Siberian Jay ''Perisoreus infaustus'' in managed and unmanaged forest | journal=Ornis Fennica | volume=79 | pages=26–33 |url=https://lintulehti.birdlife.fi:8443/pdf/artikkelit/327/tiedosto/of_79_26-33_artikkelit_327.pdf }}</ref> High breeding success has been linked to high foliage density, as this provides better hiding places for eggs and nestlings, making them less likely to attract predators.<ref name = "Ekman and Griesser 2016">{{cite book | author1 = Ekman, Jan |author2 = Griesser, Michael | year = 2016 | chapter = Siberian jays: delayed dispersal in the absence of cooperative breeding | title = Cooperative breeding in vertebrates: studies of ecology, evolution, and behavior | pages = 6–18 | doi = 10.1017/CBO9781107338357.002 | publisher = Cambridge University Press | editor1 = Walt Koenig | editor2 = Janis L Dickinson | isbn = 978-1-107-04343-5}}</ref> Additionally, the benefit of increased predator evasion through more hiding space would probably outweigh the cost of making predators more difficult to see by the jays within the dense foliage.<ref name = "Nystrand">{{Cite journal | last=Nystrand | first=Magdalena | date=2006 | title=Influence of age, kinship, and large-scale habitat quality on local foraging choices of Siberian jays | journal=Behavioral Ecology | volume=17 | issue=3 | pages=503–509 | doi=10.1093/beheco/arj055 | doi-access=free }}</ref> The Siberian jay is notably selective in its choice of territory, with a typical territory comprising old dense spruce swamp with ample vegetation cover.<ref name = "Edenius and Meyer 2002"/> Territories also tend to be structurally diverse, comprising scrub of various ages, groves and flood meadows. Therefore, active territories can be considered an indicator of a forest's high ecological diversity.<ref name = "Fabricius"/>
==Behaviour and ecology== The species has a complex and unusual social structure.<ref name="Ekman and Sklepkovych"/> Siberian jays live in small flocks of 2–7 individuals, with the dominant breeding pair at the centre of the group;<ref name = "Griesser 2003">{{Cite journal | last=Griesser | first=Michael | date=2003 | title=Nepotistic vigilance behavior in Siberian jay parents | journal=Behavioral Ecology | volume=14 | issue=2 | pages=246–250 | doi=10.1093/beheco/14.2.246 | doi-access=free}}</ref><ref name = "Griesser 2015">{{Cite journal | last1=Griesser | first1=M. | last2=Halvarsson | first2=P. | last3=Drobniak | first3=S.M. | last4=Vilà | first4=C. | date=2015 | title=Fine-scale kin recognition in the absence of social familiarity in the Siberian jay, a monogamous bird species | journal=Molecular Ecology | volume=24 | issue=22 | pages=5726–5738 | doi=10.1111/mec.13420| pmid=26460512 | bibcode=2015MolEc..24.5726G |url=https://www.zora.uzh.ch/id/eprint/120576/1/resubmission_4.pdf }}</ref> alongside retained multigenerational offspring and unrelated immigrants.<ref name="Ekman and Sklepkovych"/><ref name = "Griesser 2015"/> Within a group, there is a dominance hierarchy; whereby males are dominant over females and breeders are dominant over non-breeders; with some male non-breeders being dominant over female breeders.<ref name="Ekman and Sklepkovych"/> The composition of the flocks varies. Some comprise only family members and families associated with non-related immigrants. Others contain only nonrelated individuals.<ref name = "Griesser 2003"/> Immigrants that are unrelated to the existing population can be tolerated within the territory outside nesting areas.<ref name = "Coombs"/>
Siberian jays are aggressive towards unrelated intruders on their territory. Two different aggressive responses have been observed in territory holders within feeding grounds: (1) the intruder is approached and forced away; or (2) the intruder is chased while in flight. However, the latter behaviour is more costly to the aggressor.<ref name="Ekman and Sklepkovych"/> Although breeders are considerably more aggressive toward immigrants than retained offspring,<ref name="Ekman and Sklepkovych"/> aggressive responses appear to be modified by social dominance within groups.<ref name = "Griesser 2015"/> For example, females have been found to receive significantly more aggression than males because males show more resistance on account of their higher social ranking, therefore resulting in a higher energy cost on the part of the aggressor.<ref name = "Griesser 2015"/> Siberian jays also appear to recognise their own young through associative learning as opposed to genetic cues, as shown by experiments in which Siberian jays did not differentiate between own and fostered offspring.<ref name = "Griesser 2015"/>
===Breeding=== [[File:Perisoreus infaustus MWNH 1368.JPG|thumb|Eggs in the Museum Wiesbaden]] Siberian Jays are strictly monogamous, with an established pair staying together and holding the same territory for life.<ref name=Blomgren/> Mate guarding in both sexes has been observed, whereby males and females become increasingly aggressive toward same-sex conspecifics.<ref name = "Ruth">Ruth L. 2016. Mate-guarding in the Siberian jay (Perisoreus infaustus). Biology Independent Research Project, Karlstads Universitet.</ref> This may prevent extra-pair mating opportunities for the partner and thereby preserve inclusive fitness for both pair members.<ref name = "Ruth"/> The size of the territory is {{cvt|1|to|4|km2}}, which is slightly enlarged in autumn and winter.<ref name=Blomgren/><ref name=Lillandt>{{Cite journal | last1=Lillandt | first1=B.-G. | last2=Bensch | first2=S. | last3=von Schantz | first3=T. | date=2003 | title=Family structure in the Siberian jay as revealed by microsatellite analyses | journal=The Condor | volume=105 | issue=3 | pages=505–514 | doi=10.1093/condor/105.3.505 | doi-access=free }}</ref> Although territories are firmly established, the jays can move to a neighbouring site if this is a better quality habitat where breeding success will be higher.<ref name = "Ekman 2001">{{Cite journal | last1=Ekman | first1=J. | last2=Eggers | first2=S. | last3=Griesser | first3=M. | last4=Tegelström | first4=H. | date=2001 | title=Queuing for preferred territories: delayed dispersal of Siberian jays | journal=Journal of Animal Ecology | volume=70 | issue=2 | pages=317–324 | doi=10.1111/j.1365-2656.2001.00490.x | doi-access= | bibcode=2001JAnEc..70..317E }}</ref><ref name = "Ekman and Griesser 2016"/> Widowed individuals have been observed to establish new pair bonds.<ref name=Lillandt/>
The nest is situated in a pine or spruce tree {{convert|4-6|m|ft|abbr=on}} above ground<ref name=Blomgren/> within dense foliage for optimal concealment from nest predators.<ref name = "Eggers 2006">{{Cite journal | last1=Eggers | first1=S. | last2=Griesser | first2=M. | last3=Nystrand | first3=M. | last4=Ekman | first4=J. | date=2006 | title=Predation risk induces changes in nest-site selection and clutch size in the Siberian jay | journal=Proceedings of the Royal Society B: Biological Sciences | volume=273 | issue=1587 | pages=701–706 | doi=10.1098/rspb.2005.3373| pmid=16608689 | pmc=1560074 }}</ref> The nest comprises a loose cup of dry twigs broken off trees by the jays<ref name=Blomgren/> and is thickly lined with beard lichen moss, down feathers, cobwebs, reindeer fur and wasp nest fragments; which serves as necessary insulation against the extreme winter cold.<ref name = "Coombs"/> Nest material is hoarded in winter long before building takes place.<ref name=Blomgren/> Nest building proper begins in late March and lasts for about three weeks.<ref name = "Coombs"/> Both partners collect nest material; but only the female builds the nest.<ref name=Blomgren/>
The eggs are pale green, blue or grey and spotted with grey and brown. The average size is {{cvt|31.6|x|22.9|mm}}.<ref>Harrison C. 1975. ''A Field Guide to the Nests, Eggs and Nestlings of British and European Birds''. London</ref> They are laid 31 March – 22 April, with a variable clutch size of 1–5 and an incubation period of about 19 days.<ref name = "Coombs"/><ref name = "Eggers 2006"/> The eggs are incubated entirely by the female,<ref name = "Eggers 2006"/> whilst the male provides all the food for the brooding female and the chicks.<ref name = "Eggers 2002">Eggers S. 2002. Behaviour and life-history responses to chick provisioning under the risk of nest predation. PhD dissertation, Uppsala University.</ref> The Siberian jay is single brooded and does not relay in a breeding season even after nest failure, but will wait until next year.<ref name = "Eggers 2006"/> A new nest is also built for every breeding attempt.<ref name = "Eggers 2006"/> Newly hatched young are almost bare and are closely covered by the female. Juveniles look similar to adults, but have paler heads.<ref name = "Coombs"/>
A high proportion of the young's diet comprises insect larvae, which the male collects and stored in his oesophagus until he returns to the nest to regurgitate it and feed it to the young.<ref name = "Coombs"/> In the first week of brooding, the male provides all the food for the female and young, but the female takes an increasing share of the work thereafter.<ref name=Blomgren/>
The young fledge in mid-May to early June and leave the nest around this time, 18–24 days after the first chick has hatched;<ref name = "Coombs"/><ref name=Lillandt/><ref name = "Eggers 2002"/> although they usually hide within tree branches on the territory until they are able to properly fly.<ref name = "Fabricius"/> Parents continue to feed the young for about three weeks after fledging, with all of them remaining in a family group throughout summer, autumn and winter.<ref name=Blomgren/> Most mature young disperse from the natal territory in their first summer 4–8 weeks after fledging to join new groups which are usually situated more than four territories away from the natal one.<ref name = "Griesser 2008">{{Cite journal | last1=Griesser | first1=M. | last2=Nystrand | first2=M. | last3=Eggers | first3=S. | last4=Ekman | first4=J. | date=2008 | title=Social constraints limit dispersal and settlement decisions in a group-living bird species | journal=Behavioral Ecology | volume=19 | issue=2 | pages=317–324 | doi=10.1093/beheco/arm131 | doi-access=free }}</ref> These early dispersers are generally subordinates which have been out-competed and displaced by one or a few socially dominant offspring that are retained.<ref name="Ekman and Sklepkovych"/><ref name = "Ekman and Griesser 2016"/> If offspring have not yet dispersed by the time they are eight weeks old, they usually remain in the natal territory at least through the first winter.<ref name = "Ekman and Griesser 2016"/> The retained, socially dominant offspring remaining on the natal territory may wait for up to five years before dispersing, whenever a suitable breeding opportunity arises.<ref name = "Ruth"/> Retained offspring can also claim their natal territory, but this happens only in the rare event that both parents disappear from the territory within a relatively short time.<ref name = "Ekman and Griesser 2016"/> Offspring may inherit the new territory to which they disperse and at which they breed.<ref name = "Ekman and Griesser 2016"/> However, if there are no vacant territories to occupy, juveniles can join a different family group to gain feeding advantages and may even attempt to establish their own territory at the age of 2–3 years.<ref name = "Fabricius"/>
Retention of some offspring in the natal territory after fledging is probably best explained by the nepotism (favoritism granted by individuals to related individuals of the same species) which parents show towards them.<ref name = "Ekman and Griesser 2002">{{Cite journal | last1=Ekman | first1=Jan | last2=Griesser | first2=Michael | date=2002 | title=Why offspring delay dispersal: experimental evidence for a role of parental tolerance | journal=Proceedings of the Royal Society of London. Series B: Biological Sciences | volume=269 | issue=1501 | pages=1709–1713 | doi=10.1098/rspb.2002.2082| pmid=12204132 | pmc=1691083 }}</ref> Parents provide retained offspring with reliable access to resources and antipredator protection,<ref name = "Nystrand"/> thereby imparting to them a survival advantage<ref name = "Griesser 2003"/><ref name = "Ekman and Griesser 2016"/> (in turn with an inclusive fitness advantage to the parents). Although delayed dispersal of offspring may be explained by "queueing" for available high-quality territories for the offspring to occupy,<ref name = "Ekman 2001"/> the influence of nepotism has been shown experimentally. In removal experiments in which a father alpha male in a group was replaced with a new male unrelated to the offspring, the offspring were more likely to disperse prematurely; probably because the new male did not impart the same nepotistic advantages to the now unrelated young.<ref name = "Ekman and Griesser 2002"/> Although retained offspring may incur an initial cost of postponing breeding, this may be offset by enhanced breeding success later in life as a result of resource advantages gained from nepotistic parents;<ref name = "Ekman and Griesser 2016"/> and late dispersers have been found to have higher lifetime reproductive success than early dispersers.<ref>{{Cite journal | last1=Ekman | first1=J. | last2=Bylin | first2=A. | last3=Tegelstrom | first3=H. | date=1999 | title=Increased lifetime reproductive success for Siberian Jay (''Perisoreus infaustus'') males with delayed dispersal | journal=Proceedings of the Royal Society B | volume=266 | issue=1422 | pages=911–915 | doi=10.1098/rspb.1999.0723 | pmc=1689928 }}</ref>
At least one offspring usually remains with the parents after successful reproduction and regularly accompanies the pair for at least a year before dispersing;<ref name = "Ekman 1996"/> although some retained offspring may delay their dispersal for up to five years.<ref name="Ekman 2001"/><ref name = "Griesser 2008"/> These are the dominant offspring which out-compete and expel their subordinate siblings.<ref name = "Griesser 2003"/> The dispersed subordinate individuals (which disperse in their first summer) settle as non-breeding immigrants in other existing flocks<ref name = "Ekman and Griesser 2002"/><ref name = "Griesser 2008"/><ref name = "Griesser 2014">{{Cite journal | last1=Griesser | first1=M. | last2=Halvarsson | first2=P. | last3=Sahlman | first3=T. | last4=Ekman | first4=J. | date=2014 | title=What are the strengths and limitations of direct and indirect assessment of dispersal? Insights from a long-term field study in a group-living bird species | journal=Behavioral Ecology and Sociobiology | volume=68 | issue=3 | pages=485–497 | doi=10.1007/s00265-013-1663-x|url=https://www.zora.uzh.ch/id/eprint/171967/1/ZORA_NL_171967.pdf }}</ref> and tend to disperse much further than their dominant siblings, which more often move straight into a breeding position in a new territory.<ref name = "Griesser 2014"/> Unusually for a gregarious corvid species, members in a group of Siberian jays do not help the parents raise younger siblings in future cohorts (i.e., there is no cooperative breeding) and so offspring retention is not explained by cooperative breeding.<ref name="Ekman and Sklepkovych"/> Groups also stay together outside the breeding season, which is another unusual phenomenon.<ref name = "Ekman 2001"/><ref name=Lillandt/>
===Feeding=== The Siberian Jay is omnivorous, feeding mainly on berries, seeds, insects and spiders.<ref>{{ cite journal | last=Virkkala | first=Raimo | date=1988 | title=Foraging niches of foliage-gleaning birds in the northernmost taiga in Finland | journal=Ornis Fennica | volume=65 | pages=104–113 |url=https://lintulehti.birdlife.fi:8443/pdf/artikkelit/630/tiedosto/of_65_104-113_artikkelit_630.pdf }}</ref> Flocks will also feed on large carcasses killed by mammalian predators such as wolves and wolverines.<ref name = "Ekman and Griesser 2016"/> Other occasional food items include eggs of small birds, tit nestlings, snails, slugs, small mammals and lizards.<ref name=Blomgren/><ref name = "Fabricius"/> In autumn and winter, berries (especially bilberries and cowberries) are typically collected and stored behind loose bark or in hanging beard lichen and between forked twigs.<ref name = "Blomgren"/><ref name = "Coombs"/> Siberian jays distribute many different hidden food caches over a large area and are therefore known as scatter hoarders.<ref name = "Ekman 1996">{{Cite journal | last1=Ekman | first1=J. | last2=Brodin | first2=A. | last3=Bylin | first3=A. | last4=Sklepkovych | first4=B. | date=1996 | title=Selfish long-term benefits of hoarding in the Siberian jay | journal=Behavioral Ecology | volume=7 | issue=2 | pages=140–144 | doi=10.1093/beheco/7.2.140 | doi-access=free }}</ref> However, unlike in other corvids, this hidden food stash is not purposefully shared with siblings to increase inclusive fitness but is consumed by the hoarder or a pilferer for selfish use.<ref name = "Ekman 1996"/> These food caches are critical to this species' winter survival since foraging time is greatly restricted by the few hours of daylight.<ref name = "Hogstad"/> To securely store food, Siberian jays have developed special saliva glands which they use to form sticky food clumps which they can adhere to beard moss or holes in tree bark where they are readily accessible throughout the winter.<ref name = "Fabricius"/> Because of their reliance on food stores during winter, these birds are territorial and hold food reserves scattered around the territory, especially near to the nest.<ref name = "Fabricius"/>
When foraging, Siberian jays often stay within the closed-canopy forest to avoid visual detection by predators,<ref name = "Hogstad"/> although they may occasionally forage for insects in wet, tussock-strewn open areas.<ref name=Blomgren/> They forage in flocks comprising 3–5 individuals within their large territory.<ref name = "Ekman 1996"/> Especially in winter, Siberian jays will also venture into increasingly open areas to take and store small rodents for food when the latter are abundant.<ref name = "Hogstad"/>
==Threats== Birds of prey, especially hawks such the goshawk and sparrowhawk, are the main predators of Siberian jays.<ref name = "Griesser 2003"/><ref name = "Hogstad"/> Most Siberian jay predators detect prey visually, so that the combination of ample forest foliage cover with the jays' cryptic colouration and secretive nesting helps render the jays inconspicuous to potential predators.<ref name = "Eggers 2005">{{Cite journal | last1=Eggers | first1=S. | last2=Griesser | first2=M. | last3=Andersson | first3=T. | last4=Ekman | first4=J. | date=2005 | title=Nest predation and habitat change interact to influence Siberian jay numbers | journal=Oikos | volume=111 | issue=1 | pages=150–158 | doi=10.1111/j.0030-1299.2005.13802.x| bibcode=2005Oikos.111..150E }}</ref> Predators of this species' eggs and young include squirrels, ravens, hooded crows, magpies and Eurasian jays. The nest is constructed within the dense foliage to avoid attracting the attention of predators. Females also appear to lay smaller clutches under higher predation pressure, which may help to avoid attracting predator attention to the nest since fewer visits to the nest by the parent are necessary.<ref name = "Eggers 2006"/> Further, in higher cover nests, chicks are fed by the parent more evenly than in exposed nests more detectable by predators; so that chicks raised in well-concealed nests are expected to have better growth.<ref name ="Eggers 2006"/>
The European expanse of the population is threatened by habitat degradation through the encroachments of forestry, road building, settlements and agriculture.<ref>{{ cite book | editor1-last=Hagemeijer | editor1-first=E.J.M. | editor2-last=Blair | editor2-first=M.J. | date=1997 | title=The EBCC Atlas of European breeding Birds: their Distribution and Abundance | location=London | publisher=T. and A. D. Poyser | isbn=978-0-85661-091-2 }}</ref> Modern European forestry practices in particular may be lessening the quality of breeding habitats for the Siberian jay by depriving the birds of sufficient foliage cover.<ref name = "Eggers 2006"/> This may occur through forest thinning, whereby lower-quality trees are regularly removed from forest stands. Excessive clearcutting has been linked with increased territory abandonment by Siberian jays, leading to strong decreases in the species' breeding success in affected areas.<ref name = "Griesser 2007">{{Cite journal | last1=Griesser | first1=M. | last2=Nystrand | first2=M. | last3=Eggers | first3=S. | last4=Ekman | first4=J. | date=2007 | title=Impact of forestry practices on fitness correlates and population productivity in an open-nesting bird species | journal=Conservation Biology | volume=21 | issue=3 | pages=767–774 | doi=10.1111/j.1523-1739.2007.00675.x| pmid=17531054 | bibcode=2007ConBi..21..767G |url=http://eprints.whiterose.ac.uk/2591/2/griesserm1_Text_Griesser_et_al_M%2523E99B2.pdf }}</ref> Another practice which may threaten the Siberian jay has been the large-scale removal of stands of native spruce to be replaced with pine, potentially leading to loss of sufficient visual cover of nesting activity from predators with removal of spruce.<ref name = "Edenius and Meyer 2002"/> In Finland, spruce has also been declining faster than other forest types and loss and fragmentation of spruce forests through forestry has been linked with population declines here.<ref name = "Muukonen">{{Cite journal | last1=Muukkonen | first1=P. | last2=Angervuori | first2=A. | last3=Virtanen | first3=T. | last4=Kuparinen | first4=A. | last5=Merila | first5=J. | date=2012 | title=Loss and fragmentation of Siberian jay (''Perisoreus infaustus'') habitats | journal=Boreal Environment Research | volume=17 | pages=59–71 |url=https://helda.helsinki.fi//bitstream/handle/10138/165138/ber17_059.pdf?sequence=1 }}</ref> Anthropogenic habitat loss may be interacting with natural threats from predators. The Siberian jay population has declined more than can be explained by anthropogenic forest clearance alone,<ref>{{Cite journal | last1=Helle | first1=Pekka | last2=Järvinen | first2=Olli | date=1986 | title=Population trends of North Finnish land birds in relation to their habitat selection and changes in forest structure | journal=Oikos | jstor=3565386 | volume=46 | issue=1 | pages=107–115 | doi=10.2307/3565386| bibcode=1986Oikos..46..107H }}</ref> which may be attributable to increased nest exposure to avian predators and other human activities favouring these predatory species.<ref name = "Eggers 2005"/> Human activity may also favour nest predators such as Eurasian jays through supplemental feeding and refuse dumpling, thereby compounding the predation pressure on Siberian jays through visual exposure to predators.<ref name = "Eggers 2005"/> Finally, destruction by felling of winter food storages in trees near territories during winter may also destroy winter food caches.<ref name = "Fabricius"/>
Alongside increased predator attention, the open land exposed as a result of forest habitat fragmentation also presents an apparently large dispersal barrier which the jays may find difficult to cross given their apparent cumbersomeness at traversing open land.<ref name = "Fabricius"/> Siberian jays also appear unable to evolve fast enough to adapt to these anthropogenic habitat and predator population changes.<ref name = "Eggers 2005"/> Because of this species' sedentary habit, there appear to be several genetically isolated subpopulations.<ref name=Uimaniemi/> Given this jay's high site fidelity, gene flow between subpopulations may have been low even before onset of modern forestry practices which have created the strong dispersal barriers.<ref name=Uimaniemi/>
==In culture and relationship with humans== [[File:Perisoreus infaustus by Magnus Körner.tif|thumb|right|Preparatory drawing of a Siberian jay by Magnus Körner for ''Illuminerade figurer till Skandinaviens fauna'' by Sven Nilsson (1840)]] Siberian jays are reported to be fearless in human company, and, with repeated provision of food by humans in the same place, may become tame enough to take food from the hand.<ref name=Blomgren/> This was especially the case when forestry workers used to regularly leave patches of food scraps in the forest or around campfires for the jays to take.<ref name=Blomgren/> The Siberian jay has now gained flagship status as a conservation concern both because of threats from modern forestry and because active territories are considered a sign of high-quality biodiverse forest.<ref name = "Fabricius"/>
==Status== The Siberian jay is evaluated as Least Concern by the IUCN because of the species' exceptionally large range.<ref name="iucn status 12 November 2021" /> Although the world population is declining, the magnitude of this drop is not deemed to be sufficiently large to render the species Vulnerable.<ref name="iucn status 12 November 2021" /> The world population is very large and estimated at 4–8 million mature individuals.<ref name="iucn status 12 November 2021" /> Population declines have been reported to be strongest in the southernmost part of the range.<ref name="iucn status 12 November 2021" />
==References== {{Reflist}}
==External links== *[http://www.xeno-canto.org/species/Perisoreus-infaustus Audio recordings from Xeno-canto] *[http://www.birdlife.org/datazone/species/BirdsInEuropeII/BiE2004Sp5724.pdf An info-card on the Siberian Jay] — at [http://www.birdlife.org/ Birdlife.org]
{{Corvidae|3}} {{Taxonbar|from=Q214281}} {{Authority control}}
Siberian jay Category:Birds of Scandinavia Category:Birds of Russia Category:Birds of North Asia Siberian jay Siberian jay