The Bohemian waxwing (Bombycilla garrulus) is a starling-sized passerine bird that breeds in the northern forests of the Palearctic and North America. It has mainly buff-grey plumage, black face markings and a pointed crest. Its wings are patterned with white and bright yellow, and some of the wing feathers have red tips, the resemblance of which to sealing wax gives these birds their common name. The two or three subspecies show only minor differences in appearance. Females are similar to males, although young birds are less well-marked and have few or no waxy wingtips. Although the Bohemian waxwing's range overlaps those of the cedar and Japanese waxwings, it is easily distinguished from them by size and plumage differences.
The breeding habitat is coniferous forests, usually near water. The pair build a lined cup-shaped nest in a tree or bush, often close to the trunk. The clutch of 3–7 eggs is incubated by the female alone for 13–14 days to hatching. The chicks are altricial and naked, and are fed by both parents, initially mostly with insects, but thereafter mainly fruit. They fledge about 14–16 days after leaving the egg. Many birds desert their nesting range in winter and migrate farther south. In some years, large numbers of Bohemian waxwings irrupt well beyond their normal winter range in search of the fruit that makes up most of their diet.
Waxwings can be very tame in winter, entering towns and gardens in search of food, rowan berries being a particular favourite. They can metabolise alcohol produced in fermenting fruit, but can still become intoxicated, sometimes fatally. Other hazards include predation by birds of prey, infestation by parasites, and collisions with cars or windows. The large numbers and very large breeding area mean that it is classified as being of least concern by the International Union for Conservation of Nature.
Taxonomy The waxwings are a family, Bombycillidae, of short-tailed stocky birds with soft plumage, a head crest and distinctively patterned wings and tails. There are three species, the Bohemian, cedar, and Japanese waxwings. DNA studies and shared features such as a relatively large size, grey underparts and similar undertail patterns suggest that the Japanese and Bohemian waxwings are most closely related within the genus. Although only the cedar and Bohemian waxwings normally have red tips on their wing feathers, this feature is occasionally shown by the Japanese waxwing, suggesting that this was originally a whole-family characteristic that has been lost in one species, rather than an indicator of a close relationship. DNA analysis confirms that the cedar waxwing diverged early from the other members of the family. Outside the genus, the closest relatives of the waxwings are believed to be the silky-flycatchers, the palmchat, and the grey hypocolius, all of which have sometimes been included in the Bombycillidae.
The Bohemian waxwing was described by Carl Linnaeus in his 1758 10th edition of Systema Naturae as Lanius Garrulus.Linnaeus (1758) p. 95. The waxwings were moved to their own genus, Bombycilla, by Louis Pierre Vieillot in 1808.Vieillot (1808) p. 88. Bombycilla, the genus name, is Vieillot's attempt at Latin for "silktail", translating the German name Seidenschwänze. Vieillot thought that motacilla, Latin for wagtails, was derived from mota for "move" and cilla, which he thought meant "tail"; however, Motacilla actually combines motacis, a mover, with the diminutive suffix -illa. He then combined this "cilla" with the Latin bombyx, meaning silk. The species name garrulus is the Latin for talkative and was applied to this bird, as "Garrulus Bohemicus", by Conrad Gessner in 1555;Jobling (2010) p. 171.Gessner (1555) p. 27. the term is a reference to a supposed likeness to the Eurasian jay (Garrulus glandarius) rather than to the waxwing's vocalisations. The English name "waxwing" refers to the bright red tips of the secondary feathers on its wings, which look like drops of sealing wax, while "Bohemian" follows Gessner's usage, and may refer to the Romani, alluding to the bird's wanderings,Holloway (2003) p. 39. or to its presumed origin from Bohemia.Cocker & Mabey (2005) pp. 326–327. The spellings "Waxwing" and "Bohemian waxwing" were first recorded in 1817, the former as a reference to Vieillot's separation of this bird from the "chatterers".
There are two or three recognised subspecies: B. g. garrulus (Linnaeus, 1758): the nominate subspecies, breeds in northern Europe from northern Norway east to the Ural Mountains. B. g. centralasiae (Polyakov, 1915): breeds from the Urals eastwards across northern Asia. Included in B. g. garrulus by IOC. B. g. pallidiceps (Reichenow, 1908): breeds in northwestern North America.
The differences between these forms are small and clinal, and the species could be possibly considered as monotypic. The fossil record includes Pleistocene deposits from the UK and the Carpathian Mountains.Főzy & Szente (2013) p. 395.
Description
The Bohemian waxwing is a starling-sized bird in length with a wingspan, and an average weight of . It is short-tailed, mainly brownish-grey, and has a conspicuous crest on its head. The male of the nominate subspecies has a black mask through the eye and a black throat. There is a white streak behind the bill and a white curve below the eye. The lower belly is a rich chestnut colour and there are cinnamon-coloured areas around the mask. The rump is grey and the tail ends in a bright yellow band with a broad black border above it. The wings are very distinctive; the flight feathers are black and the primaries in adults have markings that produce a yellow stripe and white "fishhooks" on the closed wing. The adult's secondaries end in long red appendages with the sealing wax appearance that gives the bird its English name. The eyes are dark brown, the bill is mainly black, and the legs are dark grey or black. In flight, the waxwing's large flocks, long wings and short tail give some resemblance to the common starling, and its flight is similarly fast and direct. It clambers easily through bushes and trees but only shuffles on the ground.
In adults, the primary feathers have a bright yellow leading edge near the tip, and a white 'tick mark' on the tip of the trailing edge. In males, the yellow tail tip is 6–11 mm broad, the black throat is sharply defined, and there are 6–8 red waxy tips on the secondaries. Females are very similar to males, but have a narrower (4–8 mm) yellow terminal band to the tail, a less defined lower edge to the black throat and slightly fewer red tips, 5–7, on the secondaries. First-winter birds are easily distinguished from adults by the tips of the primaries, which have a white or only very pale yellow leading edge, and no white 'tick mark' on the trailing edge; they also have a slightly narrower yellow tail tip (5–10 mm in males, 2–6 mm in females), and fewer red wax tips on the secondaries, 4–6(–8) in males and (0–)1–5 in females. The juvenile plumage, only seen on the far northern breeding grounds, is markedly duller than adult plumage, with streaky, whiter underparts, no black on the throat, and a smaller black face mask; juveniles moult into first-winter plumage soon after fledging, before the end of the summer.
Compared to the nominate subspecies, eastern B. g. centralasiae is paler, greyer and has little reddish-brown behind the bill. The American subspecies B. g. pallidiceps has more colouring on the cheeks and forehead than the nominate form and is otherwise generally duller in appearance.
The soft, dense feathers are kept in good condition by preening. The red waxy tips are the extended and flattened ends of feather shafts, pigmented with astaxanthin and enclosed in a transparent sheath. A study of the cedar waxwings showed that the red tips are few or absent until the third year of life for that related species. All adult waxwings have a complete moult annually between August and January. Juveniles moult at the same time but retain their flight and some other wing feathers.
The range of the Bohemian waxwing overlaps those of both the other members of the genus. The cedar waxwing is smaller than the Bohemian; it has browner upperparts, a white undertail and a white line above the black eye patch, and lacks the white and yellow marks on the wings. Adult cedar waxwings have a yellowish belly, and all ages have less strongly patterned wings than the Bohemian waxwing.Snow & Perrins (1998) pp. 1113–1115. The Japanese waxwing is easily distinguished from its relatives; it has a red terminal band to the tail, the black mask extends up the rear of the crest, and there is no yellow stripe and few or no red tips on the wings.Brazil (2009) p. 312.
The Bohemian waxwing's call is a high trill sirrrr. It is less wavering and lower-pitched than that of the cedar waxwing,Sibley (2000) p. 423. and longer and lower-pitched than the call of the Japanese waxwing. Other calls are just variants of the main vocalisation; a quieter version is used by chicks to call parents, and courtship calls, also given during nest construction, have a particularly large frequency range. Although not a call as such, when a flock takes off or lands, the wings make a distinctive rattling sound that can be heard away.
Distribution and habitat
The Bohemian waxwing has a circumpolar distribution, breeding in northern regions of Eurasia and North America. In Eurasia, its northern nesting limit is just short of the treeline, roughly at the 10 °C July isotherm, and it breeds south locally to about 51°N. Most birds breed between 60–67°N, reaching 70°N in Scandinavia. The North American subspecies breeds in the northwestern and north central areas of the continent, its range extending southwards beyond the US border in the Rocky Mountains.
This waxwing is migratory with much of the breeding range abandoned as the birds move south for the winter. Migration starts in September in the north of the range, a month or so later farther south. Eurasian birds normally winter from eastern Britain through northern parts of western and central Europe, Ukraine, Kazakhstan and northern China to Japan. North American breeders have a more southeasterly trend, many birds wintering in southeast Canada, with smaller numbers in the north central and northeastern US states. Birds do not usually return to the same wintering sites in successive years. One bird wintering in Ukraine was found to the east in Siberia in the following year.Newton (2010) p. 406.
In some years, this waxwing irrupts south of its normal wintering areas, sometimes in huge numbers. The fruit on which the birds depend in winter varies in abundance from year to year, and in poor years, particularly those following a good crop the previous year, the flocks move farther south until they reach adequate supplies.Newton (2010) pp. 393–395. They will stay until the food runs out and move on again.Newton (2010) p. 403. In what may be the largest ever irruption in Europe, in the winter of 2004–2005, more than half a million waxwings were recorded in Germany alone. This invasion followed an unusually warm, dry breeding season. In 1908, an American flock wide was noted as taking two to three minutes to fly over.