Despite now having lived here for 4+ years, I still struggle with identifying the differences between these two swan species at times. Hearing them call is the best way to separate them for me but they are not always talking… Birders know that seeing two similar species side by side is a great way to differentiate but many times swans are distant and in large groups. Last weekend, we were able to see a single Trumpeter and a single Tundra side by side and in good light. When side by side, it is easy to see the overall size difference and different bill size and structure.
Through looking closely at these pictures and writing out some thoughts, I think I’m going to start looking more at the distinct eye field mark. Looking through pictures, this appears to be quite reliable. I guess another option is to insist they speak or line up side by side.