Animal Field Guide

Trumpeter Swan

Cygnus buccinator
(Anatidae)

Montana Species of Concern
Global Rank: G4
State Rank: S2

Agency Status
USFWS:
USFS: SENSITIVE
BLM: SENSITIVE

Trumpeter Swans are the largest waterfowl in North America. They can be up to 5 feet in length, have a wingspan up to 80 inches (almost 7 feet) and weigh over 20 pounds. Males are larger than females, but otherwise the sexes are similar in appearance. The adult Trumpeter Swan is entirely white, although the head and neck are sometimes stained an orange color due to iron-rich waters and mud where they forage for food. The webbed feet and legs are black. The bill is straight, rarely shows any yellow spot in front of the eyes (lores) and also is black. Sometimes the lower mandible shows a salmon-red line along the upper edge (Mitchell 1994). Juvenile swans are mostly white, but can retain a gray or brown head, neck and body feathers. Their feet may be yellowish, grayish or dull black. Hatchlings (cygnets) are all gray in color and have pinkish feet and a black and pink bicolored bill (Mitchell 1994).

The vocalization of Trumpeter Swans is limited to only a call sounding like oh-OH. They can make this call either with their mouths open (louder) or closed (nasal-like). Other sounds made include peeps, hisses and gurgles (Mitchell 1994).

Trumpeter Swans are similar in appearance to, but larger than, Tundra Swans. Trumpeter Swans rarely show any yellow on the lores, while Tundra Swans have very evident yellow lores (Mitchell 1994). The easiest method of separation between these two species is vocalization. Trumpeter Swans are less vocal, much lower pitched and have a more nasal quality than the louder, clearer sounds of Tundra Swans (Sibley 2000). Trumpeter Swans are also similar in size and weight to the introduced Mute Swans. However, the bill of Mute Swans is mostly orange rather than all black. Also, male Mute Swans have a black knob at the base of the bill. Trumpeter Swans do not have this knob (Mitchell 1994).

Trumpeter Swans breeding in Montana are non-migrants. They spend both the breeding season and the winter in southern Montana's lakes, ponds, and streams of the Red Rock Lakes National Wildlife Refuge. The Canadian subpopulation breeding in parts of British Columbia, Alberta, the Yukon, and the Northwest Territories will move south in late October to early November (Mitchell 1994).

Fall migration dates for the Bozeman area are November 15 to December 15 (Skaar et al. 1969). They usually follow the Rocky Mountain Front moving further south as water freezes or food diminishes. They eventually arrive in southern Montana and winter along with the resident population. Canadian swans leave their wintering grounds in early March to early April, moving up the Rocky Mountain Front toward their breeding habitat further north (Mitchell 1994). Migration dates for Bozeman are February 25 to April 15 (Skaar et al. 1969).

The breeding habitat for Trumpeter Swans in the Red Rock Lakes/ Centennial Valley of Montana includes lakes and ponds and adjacent marshes containing sufficient vegetation and nesting locations. Along the Rocky Mountain Front the breeding habitat is small pothole lakes, generally with sufficient water to maintain emergent vegetation through the breeding season (MTNHP 2003). Habitat requirements for breeding include room to take off (~100 m), shallow, unpolluted water with sufficient emergent vegetation and invertebrates, appropriate nest sites (i.e. muskrat lodges), and areas with little human disturbance (Mitchell 1994).

Their nonbreeding habitat in Montana is the many large and small lakes and ponds in extreme southern Montana, including the breeding area of the Red Rock Lakes/Centennial Valley. Swans also winter in the Ennis Lake and Madison River complex, as well as Hegben Lake and the surrounding area. During winter appropriate habitat is areas where water does not freeze and food is plentiful and accessible. Swans will move out of one lake or pond to another if conditions become too severe.

In the Yellowstone ecosystem dominant foods (>10% in at least one season) included Chara spp. (21.7%), Elodea canadensis (11.4%), Potamogeton spp. (32.2%), and Potamogeton pectinatus tubers (15.7%) (Squires and Anderson 1995); however, Hampton (1981) reported up to 10% of food was animal matter, primarily invertebrates and fish.

At Red Rocks National Wildlife Refuge, the population increased until 1954 and has declined steadily since, possibly due to a decrease in Elodea canadensis (Page 1976), or to lack of migration and the resultant poor nutritional gain, producing inviable eggs/young (Hampton 1981).

Nesting begins in late April or early May in the intermountain western U.S. Clutch size is 2 to 9, usually about 5). In Yellowstone National Park and environs, clutch size is about 4 (Shea 1979). Incubation, mainly conducted by the female, lasts 33 to 37 days (Harrison 1978). Hatching occurs in June in the intermountain western U.S. In Yellowstone National Park, the hatching rate is approximately 49%. 54% of nests hatched at least one egg. The average brood size at hatching is 3.3 and 2.0 at fledging (Shea 1979). Nestlings are precocial but remain with adults until the subsequent spring. Fledging occurs at 100 to 120 days. Young remain with parents through winter; siblings may stay together for a few years and may rejoin parents after the nesting period. Trumpeter Swans first nest at 4 to 5 years (may form pair bonds earlier) and form a life-long pair bond. Rarely does more than one pair nest on a single body of water.

The U.S. Fish and Wildlife Service, with biannual Trumpeter Swan Surveys of the Rocky Mountain Population, monitor Trumpeter Swan reproduction in Montana closely. Since 1972, every September and February surveys are initiated across southern Montana to document the presence of Trumpeter Swans. These surveys also separate the number of white birds (adult or subadult) from gray birds (cygnets). February surveys have shown some fluctuation of the wintering swan population in Montana over the last 30 years with a record high number of 704 birds (600 white and 104 gray) in 2002 and a low of 214 birds (153 white and 61 gray) in 1995 (USFWS 2003). Overall, the wintering Rocky Mountain Population has increased drastically from about 609 birds in 1973 to over 4400 in 2002. It appears the population in Montana is remaining steady, where increasing populations in Idaho and Wyoming are the cause for the overall increase in the Rocky Mountain Population (USFWS 2003). September surveys for Trumpeter Swans have been conducted since 1967. From then up to 1992, swan numbers in the state were fairly consistent with the total number of birds ranging from 202 birds (174 white and 28 gray) in 1986 to 365 (242 white and 123 gray) in 1968 (USFWS 2001). After 1992 swan numbers in the state declined drastically. Only 76 swans (60 white and 16 gray) were recorded in 1993 and since that time the highest number of Trumpeter Swans recorded was 151 (127 white and 24 gray) in 2000 (USFWS 2001). The breeding population for the entire Rocky Mountain Population has apparently remained fairly constant over the same period of time (1967-2002). 1988 recorded a high with 658 birds recorded. The low year for breeding swans was 1993 with only 354 (USFWS 2001).

Management for Trumpeter Swans began in Montana in the early 1930's with the designation of Red Rock Lakes National Wildlife Refuge (RRLNWR). This refuge was specifically created for continued Trumpeter Swan presence and for active management practices. These early management practices consisted of protection from shooting, winter feeding stations, and relocation to other breeding locations (Mitchell 1994). Some of these management activities are still in practice today, along with others including habitat restoration, human recreation management, breeding, wintering habitat management, and winter translocation work (Mitchell 1994). Since 1988, Trumpeter Swans have been relocated from Red Rock Lakes NWR in southern Montana to locations in Idaho, Oregon, Wyoming and Utah to promote exploration of new wintering and habitats and to remedy the increasing problem of overpopulation in the refuge during winter. The goal is to have less than 10% winter at any one site and no swans winter at Red Rock Lakes NWR (Baskin 1993). In 1993, winter feeding stations were terminated in the Red Rock Lakes NWR. It was believed these stations were reducing the winter range expansion work, as birds would not actively explore new wintering locations if food were made readily available in the refuge. Since then, Trumpeter Swans have indeed dispersed to new areas in the west and the remaining population in RRLNWR has stabilized. Other management techniques include the biannual Trumpeter Swan surveys conducted in the state, the management of Mute Swan populations, and the implementation of land-use guidelines on state, federal and provincial lands. All these practices are described and supported by The North American Management Plan for Trumpeter Swans (1984). As noted in the distribution comments, the Confederated Salish and Kootenai Tribes in northwestern Montana are also reintroducing Trumpeter Swans on the Flathead Indian Reservation. Trumpeter Swans are a Species of Management Concern in Region 6 (U.S. Fish and Wildlife Service 1995).