Pak Yui Arthur Tong

Trumpeter Swans were extirpated from Ontario in the late 1800s and by the early 1900s, only three breeding populations remained, with most of the surviving birds in Alaska (Pacific Coast Population), fewer in Canada (Western Canada Population), and a population in the Greater Yellowstone area of the contiguous United States. The Ontario reintroduction program ended in 2006, and limited empirical analyses have been conducted since, hence, this paper examines the Ontario breeding distribution of TRUS (1991-2021) to see if there is evidence of density dependent range expansion in areas around the captive breeding release sites. To do this, I first quantified the seasonal distribution by grid cells count (2.96 km x 2.96 km) followed by kernel density mapping. Secondly, I assessed the occurrence and extent of short-stopping by calculating the average geographic location of sightings and the minimum distance between each wintering location and release sites. These drivers acted as independent variables for the regression model, and it was found that the R2 of 0.15 (Fstat = 1117.328, p<0.0001). The most important predictor in the model was distance to release sites (-0.225), followed closely by distance to winter sites (-0.205), in which they both had a negative relationship with the dependent variable. On the other hand, human population density had a positive relationship of 0.078 with the dependent variable. The results from this study confirmed that the Ontario breeding distribution of TRUS (1991-2020) shows evidence of density dependent range expansion in areas around captive breeding release sites, confirming short-stopping in winter as well.