Siberian Jay Perisoreus infaustus Scientific name definitions

25–31 cm; 72–101 g. A drab brownish or greyish, relatively long-tailed forest jay with some rufous in tail and wing; bill short and small, with straight culmen but lower mandible somewhat upturned towards tip. Nominate race has head and nape dusky brown, blackest on lores and about eye, contrasting with very pale buff nasal tuft, and lighter buffy-grey throat and underparts , latter washed rufous-cinnamon on breast and flanks, becoming purer cinnamon on lower belly and undertail-coverts; mantle , back and scapulars buffy brown, washed grey in fresh plumage, with lower scapulars washed cinnamon; rump cinnamon-brown, grading into bright rufous on uppertail-coverts; central pair of tail feathers grey , remainder bright cinnamon-rufous , narrowly tipped and edged grey; lesser and median upperwing-coverts grey-brown to buff-brown, greater coverts (except dusky innermost) cinnamon-rufous, alula and flight-feathers blackish-grey, cinnamon-rufous wingpanel formed by bases of flight-feathers (obvious in flight), paler and more extensively pinkish-cinnamon on underside; iris dark brown; bill and legs blackish. Sexes similar in plumage, male on average larger than female. Juvenile has distinctly shorter and looser body plumage than adult, has less obvious dark hood, and is greyer overall. Races differ mainly in plumage tone and amount of rufous in wing: ostjakorum has light grey body, virtually no rufous in wing; yakutensis has very grey body and extensive rufous in wing; ruthenus is mainly rufous-buff on body, but with little rufous in wing; <em>sibericus</em> has buffish-grey body, extensive rufous wingpanels; tkachenkoi has pure grey body plumage, intermediate extent of rufous in wing; opicus is dark-hooded and rufous, with intermediate extent of rufous in wing; caudatus has dusky grey-brown body and minimal amount of rufous in wing; <em>maritimus</em> has buffish body, moderate deep rufous wingpanels.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Boreal forest (taiga zone); favours dense closed-canopy, mature forest of spruce (Picea), pines (Pinus) and larches (Larix), with stands of birches (Betula). Lowlands and foothills, to 2200 m in Altai Mts.

Sedentary over most of range. In W, rarely moves S in winter as far as St Petersburg and Moscow region, from where only two reports (both in Oct) in 60 years up to 1968. Farther E, likely that populations in extreme N move S in some winters, as indicated by Jan and Feb influxes in Yakutsk region. Vagrancy extremely rare, but reported from Estonia (where formerly bred), Latvia, Poland, Belarus, Slovakia and Ukraine.

Omnivorous. Diet includes berries, seeds, various insects and their larvae, notably beetles (Coleoptera) and moths (Lepidoptera), and wide variety of other invertebrates; feeds on carrion , and scavenges scraps provided by humans; takes eggs and nestlings of small birds, and small rodents; exceptional reports of chasing and killing adult birds, e.g. Willow Tit (Poecile montanus). Although generally unobtrusive, can be conspicuous and often very tame in remote areas, even coming to take food from the hand; scavenges at camp-sites, seeking out temporary ones by locating fires. Feeds in pairs or family groups, spending much time on the ground; in spring feeds actively in crowns of conifers, at other seasons much lower in tree foliage. Searches along branches and main trunk, pecking at scaly bark; then moves on to adjacent tree, or drops down slope to work another patch of forest. Sometimes perches briefly at top of tall conifers. On occasion will take flying insects flycatcher-fashion from treetops, or even by leaping from ground. Stores food items for winter but, unlike most other hoarding jays, conceals these in crevices of tree bark, using its very sticky saliva to stick them into position; saliva can also be used for sticking pieces of bark or needles over foodball for concealment. May store up to 200 items in one day.

Vocabulary quite varied, but all vocalizations rather subdued. Song an insignificant twittering and chattering, mixed with whistling and mewing cries, includes mimicry of other birds, i.e. tits (Paridae), Turdus thrushes, redpolls (Carduelis) and bullfinches (Pyrrhula). Most audible is a harsh "kreee", rather softer than similar call of Garrulus glandarius, and a mewing reminiscent of that of buzzard (Buteo). When agitated may give nervous, repeated "ful-ful" or "fu-fee" at variety of speeds and pitches, as well as high-pitched repeated "jik" (similar to that of some Dendrocopos woodpeckers). In recent experimental studies, this species used 14 different calls when mobbing predators; these provided information to other group-members about both the category of predator and, simultaneously, the risk posed by it at the particular time.

Breeds late Mar to May. Monogamous, with lifelong pair-bond. Solitary nester, but additional bird sometimes present with pair and may help with incubation or brood-feeding (such helpers probably relatives and young birds from previous breeding season); nests 500–1000 m apart. Male initiates building, soon joined by female, construction work taking 11–26 days; nest a rather loose structure of twigs, with well-lined cup of lichens, feathers and reindeer (Rangifer) hairs, placed at base of branch close to trunk of tree; breeding territory 45–57 ha. Clutch 3–4 eggs, but 6 reported from nest with two females sharing incubation; incubation wholly by female, period 19 days; chicks brooded by female, fed only by male for first few days, thereafter fed by both sexes, nestling period 21–24 days; after leaving nest young fed by adults for at least a month, but often beg throughout first year. May breed in parents' territory in second year, but most do not commence breeding until they have established own territory, typically in third year. Oldest ringed individual reached 11 years 5 months.

Not globally threatened. Common to abundant; unobtrusive habits no doubt give false impression of scarcity, but this species, with a range extending across entire length of boreal zone of Palearctic Region, must have a very large global population. In parts of European range it is declining, owing to felling and fragmentation of forests, the latter opening up dense forest and allowing such predators such as Corvus corax easier access to nests of this and other bird species. Most noticeable range contraction has been in NE Baltic; probably ceased breeding in Estonia in mid-19th century, since when has become hardly more than a vagrant there; marked decrease in Finland, population falling by two-thirds between 1940s and 1970s, decline continuing into 1990s, and in 1992 Finnish population estimated at between 40,000 and 70,000 pairs. Despite quite extensive forest clearance in N Sweden, a decrease has hardly been noticed in either Sweden or Norway; Swedish population estimated at 50,000–200,000 pairs, with between 10,000–50,000 pairs in Norway and between 10,000 and 100,000 pairs in European Russia. Little published on populations of C & E Siberia, although population density seems to be greater in C Siberia than in Europe; as many as 12–16 birds/km² reported from mixed fir, birch and larch forests of S taiga of C Siberia, whereas densities in prime habitats in N Sweden have not exceeded 2 birds/km².