The largest native North American waterfowl, the Trumpeter Swan is a long-lived, social species, conspicuous by its large size, all-white plumage, and trumpet-like call. Although it was formerly abundant and geographically widespread, its numbers and distribution were greatly reduced during the early fur trade and European settlement of North America (1600s-1800s), when it was prized for its skins and primary feathers. Only 69 individuals were known to exist in 1935, but unrecorded flocks also inhabited parts of Alaska and Canada. Numbers have steadily increased with conservation, including protection from shooting, habitat conservation and management, and range expansion programs. A 2005 continent-wide survey found 34,803 individuals in the wild, an increase of 11,156 swans since the 2000 survey ( Moser 2006 ).
Because of its long life, delayed maturation, single broods, and highly variable production, population growth of this species is sometimes slow. Although its numbers and distribution are increasing, some populations are still at risk from poor quality breeding habitat, continued loss of wintering habitat, concentration of wintering flocks at relatively few sites, and lead poisoning.
Trumpeter Swans use a wide variety of breeding and wintering habitats that provide open water, access to food, and security from disturbance. Migratory behavior also differs widely within and between flocks. This, along with different patterns of habitat use and demography, makes it mandatory to manage flocks on an individual basis. This in turn requires flock specific biological and behavioral data.
The most comprehensive references on Trumpeter Swans remain Banko ( Banko 1960 ), Hansen et al. ( Hansen et al. 1971 ), and the unpublished reports by Gale et al. ( Gale et al. 1987 ), and Lockman et al. ( Lockman et al. 1987b ). Much useful information is contained in The Trumpeter Swan Society's newsletters and in the journal North American Swans, the Proceedings and Papers of the various Trumpeter Swan Society Conferences, and unpublished university theses. Scott and the Wildfowl Trust ( Scott 1972 ) and the Second ( Matthews and Smart 1981 ), Third ( Sears and Bacon 1991 ) and Fourth ( Rees and Earnst 2002 ) International Swan Symposia are also excellent sources on swans in general, including Trumpeter Swans.