Named for the nomadic ranging patterns of its winter flocks, the Bohemian Waxwing moves widely, seeking crops of winter fruits, and irregularly sweeps into regions to the south and east of its typical winter range. This species has a Holarctic distribution, breeding in open boreal forests. It has 2 close relatives: the Cedar Waxwing (Bombycilla cedrorum), which has a more southerly distribution across North America, and the Japanese Waxwing (B. japonica), which occurs in eastern Asia.
Like the Cedar Waxwing, the Bohemian Waxwing feeds primarily on sugary fruits during most of the year. Much of its natural history is tailored to this dietary specialization. It feeds heavily on insects during the warmer months, gleaning them from vegetation or sallying for aerial insects as they emerge from streams, lakes, or ponds. Breeding and seasonal movements appear to depend largely on temporal availability and spatial distribution of fruit crops. Late breeding coincides with the ripening of a new season's fruits. The Bohemian Waxwing is monogamous and nonterritorial, likely because its fruit foods are not defensible owing to their typically ephemeral and abundant nature. As a consequence of nonterritoriality, waxwings do not have true songs. Indeed, the hallmark of this family is a high degree of apparent cooperation associatedwith finding and feeding on scattered, abundant fruit crops. Waxwings are gregarious, forming large migratory and winter flocks in which individuals associate closely, with little antagonism. Breeding sites vary between years, and pairs may also nest and feed close together, suggesting that individuals monitor fruit supplies that are known to vary locally from year to year. In the wild and even when confined in close quarters, waxwings are docile, perching calmly close to one another. Although lacking song, waxwings have a diversity of call types used in different social contexts that appear to have diverse and subtle meanings.
Adults and some juveniles of both Bohemian and Cedar waxwings have variable numbers of red, waxlike nubs on the tips of their secondaries. The body of evidence indicates that these plumage ornaments serve an important role in the social biology of waxwings. The waxlike tips and other plumage characters increase in number and/or prominence with age, and more mature mates fledge more young. The brightness and size of the yellow tail band also increases with age, and in Bohemian Waxwings the primary wing-stripe becomes brighter yellow and the pale pigmentation increases to include the tip of the inner web of the primaries, creating a terminal white crescent. The red and yellow carotenoid pigments of waxwing plumage are derived exclusively from dietary sources, so resulting ornamentation is linked to feeding habits.
Intensive studies of this species are lacking. Howell ( Howell 1973 ) described call types and their social contexts in a comparative study of Cedar and Bohemian waxwings. S. and M. Houston have banded wintering birds in Saskatchewan, Canada, for many years, showing that many individuals remain in the locality for extended periods (see Migration: migratory behavior, below).