The trumpeter swan feeds mainly on plants, including the leaves, stems, roots and tubers of submerged and emergent vegetation, often supplemented with grasses and small grains (2) (3) (4). Very occasionally, the trumpeter swan may eat fish or fish eggs, and the cygnets often consume aquatic invertebrates (3).
As well as foraging by touch and by sight, on and below the water, the trumpeter swan may dig in soil when looking for foods such as tubers (3). Like many other waterfowl species, it often feeds at night, particularly in winter (5). The trumpeter swan feeds at a particularly high rate during spring, to build up its reserves prior to nesting (5).
Migratory trumpeter swans typically return to their northern breeding grounds between February and March (3). A monogamous species, the trumpeter swan may form a pair bond with a mate from about 20 months old, although most bonds do not develop firmly until about 3 or 4 years of age. A pair will often inhabit a wetland area for several years before eventually nesting there (3). The breeding pair stays together throughout the year and usually mates for life, although some individuals have been known to ‘divorce’ their mate and be serially monogamous. Some males never pair again after the death of a mate (2) (3).
The breeding season of the trumpeter swan can vary widely both by region and with weather patterns. However, most egg-laying takes place between late April and May (3). Both the male and female trumpeter swan help build the nest, which consists of a large, open bowl of aquatic vegetation, grasses and sedges, lined with feathers, and usually located on a slightly elevated site surrounded by water (2) (3). The trumpeter swan is territorial when breeding, and may attack intruding swans, as well as other species (3).
The trumpeter swan lays up to 9 creamy-white eggs, which are incubated, mainly by the female, for 32 to 37 days. The young swans are able to leave the nest within a day of hatching, and are capable of swimming and feeding themselves (2) (3). The young are able to fly after about 84 to 122 days (3). In migratory populations, the trumpeter swans usually move south in September or October, although some individuals stay until the water freezes in November (3).
The trumpeter swan is relatively long-lived, surviving for up to 24 years in the wild or over 32 years in captivity (2) (3).