There is no abstract available for this thesis.

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.

Fifty-seven Trumpeter swans (Cygnus buccinator) were translocated to the Bear River Migratory Bird Refuge and the Bear River Club Company in northern Utah. The purpose of this effort was to encourage dispersal of the Rocky Mountain population of Trumpeter swans during the winter, and to reestablish a migratory route to southern wintering grounds. I assessed the success of the translocation by evaluating 13 translocation criteria proposed in the literature. In this study I addressed two of these criteria in detail by evaluating habitat quality at the translocation sites and by analyzing potential competitive interactions with Tundra swans (Cygnus columbianus). Habitat quality was determined by analyzing the spatial distribution of sago pondweed (Potamogeton pectinatus) tubers in wetland sediments before the fall and after the spring migration of Tundra swans. Sixty-four transects were established within the study sites with 10 sediment cores per transect. Geostatistical procedures were employed to account for autocorrelation between samples. Tuber biomass was not randomly distributed within the studied wetlands. In fact, discrete areas of high values appeared to exist before and after swan foraging . It is not likely that sago pondweed tubers are limiting swan abundance in this system. Thus, the habitat quality of the study sites is sufficient for Trumpeter swan translocation. Potential competitive interactions with Tundra swans were evaluated by examining differences in resource utilization patterns of the two species. I measured body size differences, dietary overlap, resource availability, and the efficiency of extracting available resources. Trumpeter swans appear to benefit from a larger body size and a longer neck because they are more efficient in extracting tubers from the sediment, and are able to exploit tubers to a greater sediment depth than Tundra swans. However, Trumpeter swans incur higher traveling costs due to the larger body size. The trade-off between higher foraging efficiency of Trumpeter swans and higher traveling efficiency of Tundra swans may be a potential mechanism for coexistence. Lack of support by governmental and non-governmental agencies did not allow for more than one year of translocation. Even though the Trumpeter swan translocation in 1996 was successful, I concluded that the Utah translocation program failed because the translocation did not meet translocation goals.