Factors Affecting the Harvest Vulnerability of Trumpeter Swans

Two species of swan are regularly found in Utah, tundra swans (Cygnus columbianus) and trumpeter swans (Cygnus buccinator). Tundra swans migrate through Utah. During the fall migration period they are hunted in the state under guidelines established by the United States Fish and Wildlife Service (USFWS). Trumpeter swans are occasional visitors to Utah during the same migration period. Because trumpeter swans are difficult to distinguish from tundra swans in flight, they 11 are at risk of being harvested during the swan hunt. In my thesis, I examine the factors that may influence trumpeter swan vulnerability to harvest. Specifically, I evaluated height and velocity of foraging flights for both species of swans and identified characteristics of Utah swan hunters. This information could assist the Utah Division of Wildlife Resources in developing an educational program to reduce trumpeter swan vulnerability. I applied flight dynamics theory to 86 trumpeter and 178 tundra swan measurements. Both speed and height of short-range foraging flights were used to predict trumpeter and tundra swan vulnerability. The theory predicted that trumpeter swans fly slower and lower than tundra swans, and thus may be more vulnerable to harvest. The predicted flight height of tundra swans was compared to observations of tundra swans made at the USFWS Bear River Migratory Bird Refuge. Average body area of the two species of swans was compared. Trumpeter swans had, on average, a 30% larger body area. Combining the lower predicted flight and larger body size, trumpeter swans may be up to 26% more vulnerable on a 3.8-km flight and 15% more vulnerable on a 10-km flight than tundra swans on the same flight path. In addition to current regulations, the Utah Division of Wildlife Resources is interested in implementing a swan hunter education course to further reduce the likelihood of a trumpeter swan being harvested during the swan hunt. I surveyed a representative sample of Utah swan hunters to determine if they would participate in the course and attitudes about current regulations, and to identify specific topics that should be emphasized in the course. My survey suggested that Utah swan hunters would be receptive to a swan hunter education course. Based on the responses, any swan hunter education course should emphasize identification of trumpeter and tundra swans, distance estimation, and regulations regarding the swan hunt